Articles de revues : « Anthropogenic Seismic Sources »

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Lecocq, Thomas, Stephen P. Hicks, Koen Van Noten, Kasper van Wijk, Paula Koelemeijer, Raphael S. M. De Plaen, Frédérick Massin et al. « Global quieting of high-frequency seismic noise due to COVID-19 pandemic lockdown measures ». Science 369, n^o 6509 (23 juillet 2020) : 1338–43. http://dx.doi.org/10.1126/science.abd2438.

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Human activity causes vibrations that propagate into the ground as high-frequency seismic waves. Measures to mitigate the coronavirus disease 2019 (COVID-19) pandemic caused widespread changes in human activity, leading to a months-long reduction in seismic noise of up to 50%. The 2020 seismic noise quiet period is the longest and most prominent global anthropogenic seismic noise reduction on record. Although the reduction is strongest at surface seismometers in populated areas, this seismic quiescence extends for many kilometers radially and hundreds of meters in depth. This quiet period provides an opportunity to detect subtle signals from subsurface seismic sources that would have been concealed in noisier times and to benchmark sources of anthropogenic noise. A strong correlation between seismic noise and independent measurements of human mobility suggests that seismology provides an absolute, real-time estimate of human activities.

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Schippkus, Sven, Mikaël Garden et Götz Bokelmann. « Characteristics of the Ambient Seismic Field on a Large-N Seismic Array in the Vienna Basin ». Seismological Research Letters 91, n^o 5 (29 juillet 2020) : 2803–16. http://dx.doi.org/10.1785/0220200153.

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Abstract The ambient seismic field is now routinely used for imaging and monitoring purposes. Most commonly, applications aim at resolving crustal-scale features and utilize ocean-generated surface waves. At smaller scales and at frequencies above the microseismic peaks, local sources of seismic energy, often anthropogenic, are dominant, and understanding of their contributions to the ambient seismic field becomes important to apply ambient noise techniques. This study uses data of an industrial-scale seismic deployment covering ∼500 km2 with 10,532 stations, each equipped with several collocated 10 Hz geophones, to provide unique insight into anthropogenic sources of seismic energy in a suburban-to-rural area. We compute amplitude levels, their distance dependency, power spectral densities, and spectrograms to describe the source characteristics. The sources we observe in great detail include windmills, a railway track and trains, cars, oil pumpjacks, power lines, gas pipelines, and airplanes. These sources exhibit time-dependent behavior that is illustrated strikingly by videos of amplitude levels in certain frequency bands that we provide as supplemental material. The data described in this study are a potential resource for future studies, such as automatic signal classification, as well as underground imaging using microseismic noise or the sources presented here.

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Zhu, Tieyuan, Junzhu Shen et Eileen R. Martin. « Sensing Earth and environment dynamics by telecommunication fiber-optic sensors : an urban experiment in Pennsylvania, USA ». Solid Earth 12, n^o 1 (28 janvier 2021) : 219–35. http://dx.doi.org/10.5194/se-12-219-2021.

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Abstract. Continuous seismic monitoring of the Earth's near surface (top 100 m), especially with improved resolution and extent of data both in space and time, would yield more accurate insights about the effect of extreme-weather events (e.g., flooding or drought) and climate change on the Earth's surface and subsurface systems. However, continuous long-term seismic monitoring, especially in urban areas, remains challenging. We describe the Fiber Optic foR Environmental SEnsEing (FORESEE) project in Pennsylvania, USA, the first continuous-monitoring distributed acoustic sensing (DAS) fiber array in the eastern USA. This array is made up of nearly 5 km of pre-existing dark telecommunication fiber underneath the Pennsylvania State University campus. A major thrust of this experiment is the study of urban geohazard and hydrological systems through near-surface seismic monitoring. Here we detail the FORESEE experiment deployment and instrument calibration, and describe multiple observations of seismic sources in the first year. We calibrate the array by comparison to earthquake data from a nearby seismometer and to active-source geophone data. We observed a wide variety of seismic signatures in our DAS recordings: natural events (earthquakes and thunderstorms) and anthropogenic events (mining blasts, vehicles, music concerts and walking steps). Preliminary analysis of these signals suggests DAS has the capability to sense broadband vibrations and discriminate between seismic signatures of different quakes and anthropogenic sources. With the success of collecting 1 year of continuous DAS recordings, we conclude that DAS along with telecommunication fiber will potentially serve the purpose of continuous near-surface seismic monitoring in populated areas.

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Dobrorodny, Vladimir I., et Oksana A. Kopylova. « CHARACTERISTICS OF MICROSEISMS AND ACOUSTIC NOISES IN THE TRANSPORT POLYGON CONDITIONS ». Interexpo GEO-Siberia 4, n^o 1 (21 mai 2021) : 118–25. http://dx.doi.org/10.33764/2618-981x-2021-4-1-118-125.

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The work is related to numerical estimation and comparative analysis of microseismic and acoustic noise levels in transport polygon conditions. The aim of the work is to study and further define the difference between the signal and noise to improve the ability to detect poorly distinguishable events, as well as to study the propagation features of the interrelated seismic and acoustic wave fields. It is related to the fact that wave processes generated by many natural and anthropogenic sources are conjugate nature. In particular, it is related to simultaneous propagation of seismic waves in the ground and acoustic waves in the atmosphere. It determines expediency of taking into account simultaneously parameters of both types of waves in the tasks of geophysical monitoring of the environment, as well as in solving some applied problems of seismics and acoustics.

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Qin, Lei, Frank L. Vernon, Christopher W. Johnson et Yehuda Ben‐Zion. « Spectral Characteristics of Daily to Seasonal Ground Motion at the Piñon Flats Observatory from Coherence of Seismic Data ». Bulletin of the Seismological Society of America 109, n^o 5 (27 août 2019) : 1948–67. http://dx.doi.org/10.1785/0120190070.

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Abstract We investigate coherences of seismic data recorded during three years (2015–2017) at the Piñon Flats Observatory (PY) array and a collocated 148 m deep borehole station B084, along with oceanic data from a buoy southwest of the PY array. Seismic and barometric recordings at PY stations are analyzed with a multitaper spectral technique. The coherence of signals from seismic sources is >0.6 at 0.05–8 Hz between closely spaced (<65 m) surface stations and decreases to ∼0.2 in frequency bands in which the wavelengths are smaller than interstation distances. There are several local coherence increases at 1–8 Hz between nearby (<65 m) surface stations, whereas large coherence values between a surface and 148 m deep borehole stations are only present at the secondary microseism (∼0.14 Hz). These points to significant modification of seismic recordings in the top crust, and those continual near‐surface failures might produce shallow rapidly attenuating signals at surface stations. Incoherent local atmospheric effects induce incoherent seismic signals in low‐ and high‐frequency ranges through different coupling mechanisms. Between 0.003 and 0.05 Hz, atmospheric loadings generate ground tilts that contaminate the two horizontal seismic recordings and decrease their coherence, whereas the vertical component is less affected. At 1–8 Hz, coupling of atmospheric pressure with surface structures transmits incoherent signals into the ground, degrading the seismic coherence in all three components. The two horizontal coherences show seasonal variations with extended coherent frequency bands in winter and spring, likely to be produced by seasonal variations in microseisms and local ground tilts. The coherences also contain high anomalies between 2 and 4 Hz resulting from anthropogenic activities. The results provide useful information on instrument characteristics and variations in the shallow crustal response to earthquakes, seasonal and ambient sources of seismic energy, along with atmospheric pressure–temperature changes and anthropogenic activities.

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Harris, David, Julie Albaric, Bettina Goertz-Allmann, Daniela Kuehn, Sebastian Sikora et Volker Oye. « Interference suppression by adaptive cancellation in a high Arctic seismic experiment ». GEOPHYSICS 82, n^o 4 (1 juillet 2017) : V201—V209. http://dx.doi.org/10.1190/geo2016-0452.1.

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Mechanical and electromagnetic interference (process noise) is common in seismic data recorded to monitor and characterize induced microseismicity during industrial injection and production operations. We have developed a case study of adaptive cancellation to reduce observed process noise in passive seismic data recorded during the 2014 injection test at the [Formula: see text] Lab research site in Spitsbergen. Our results suggest that adaptive cancellation is effective when major sources of interference are readily identifiable. Adaptive cancellation requires these sources to be instrumented separately but conceivably with low-cost sensors. We suggest that adaptive cancellation should be considered routinely when planning microseismic monitoring operations when strong industrial or anthropogenic noise is anticipated. Interference suppression algorithms are sufficiently simple that they could be implemented in acquisition systems to avoid archival of noise reference data.

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Kumar, Santosh, R. Chaitanya Kumar, Ketan Singha Roy et Sumer Chopra. « Seismic Monitoring in Gujarat, India, during 2020 Coronavirus Lockdown and Lessons Learned ». Seismological Research Letters 92, n^o 2A (3 février 2021) : 849–58. http://dx.doi.org/10.1785/0220200260.

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Abstract The Gujarat region, situated in the westernmost part of India, experienced a deadly intraplate 2001 Mw 7.6 Bhuj earthquake. In the aftermath of the disaster, the Institute of Seismological Research established the Gujarat (India) seismic network in 2006. The network is being operated in online and offline modes, whereas, seismicity monitoring is being done in near-real-time, using data received from the online seismic stations. The Coronavirus disease-19 lockdown provided an opportunity to assess the network reliability in a difficult and challenging scenario. The positive aspect of the lockdown is reflected in signal-to-noise ratio, which improved significantly at all the sites during the lockdown, with more prominent being at sites located on top of the Quaternary sediments due to the absence of high-frequency anthropogenic noise. A sharp fall in the seismic background noise is noticed at most of the stations during the lockdown period, with respect to the prelockdown period. We used the lockdown data to identify other natural sources of noise, besides anthropogenic. The lockdown helped in solving the enigma of seismicity in certain pockets, which turned out to be related to quarry blasts.

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Lehujeur, Maximilien, Jérôme Vergne, Alessia Maggi et Jean Schmittbuhl. « Vertical seismic profiling using double-beamforming processing of nonuniform anthropogenic seismic noise : The case study of Rittershoffen, Upper Rhine Graben, France ». GEOPHYSICS 82, n^o 6 (1 novembre 2017) : B209—B217. http://dx.doi.org/10.1190/geo2017-0136.1.

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Correlating ambient seismic noise allows us to image the subsoil in various contexts and at different scales. Applying this technique to anthropogenic seismic noise can be challenging when the spatial distribution of the sources is not uniform. We have addressed the feasibility of exploiting this kind of noise in addition to microseismic noise to extend the reconstruction of Rayleigh-wave dispersion at periods between 0.2 and 1 s. We used data acquired with two small aperture arrays ([Formula: see text] stations with a 200 m helical distribution) deployed near the deep geothermal site of Rittershoffen (Alsace, France). In this region, the sparse human activity causes strong seismic noise, whose nonuniform spatial distribution limits our ability to determine the surface wave velocity between stations using the classical noise correlation technique at periods of less than 1 s. We have used double beamforming to isolate the noise sources that contribute constructively to the empirical Green’s function between the two arrays and recovered the Rayleigh-wave dispersion curve at periods less than 1 s. Using a probabilistic inversion, we found that such data, combined with surface wave measurements at periods greater than 1 s, are helpful to improve the reliability of [Formula: see text] and [Formula: see text] profiles at depths down to the deep-geothermal reservoir (2.5 km). Such profiles are helpful in a geothermal context because they improve the location of induced seismic events, necessary for reservoir monitoring and risk assessment.

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Ranguelov, Boyko, Ruben Paul Borg, Edelvays Spassov, Fathimath Shadiya et Antoaneta Frantzova. « Determination of Vs_30 from existing geophysical investigation data ». Engineering Geology and Hydrogeology 36, n^o 1 (10 janvier 2023) : 35–43. http://dx.doi.org/10.52321/igh.36.1.35.

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The Vs_30 refers to the velocity of transversal seismic waves in the upper earth crust (surface shallow depths) in the 0-30 m interval. This parameter reflects the integral ground properties and is used in almost all seismic hazard assessment software. The determination of Vs_30 is important, especially in the case of urban territories, where in-situ measurements are very difficult and sometimes impossible due to dense urban areas, large anthropogenic noise and the need of expensive boreholes. The paper presents a methodology for extracting necessary data and information from archival sources, mainly geophysical measurements frequently executed for different prospecting purposes. The methodology for assessment of the integral values of Vs_30 is proposed for the definition of seismic hazard maps in Bulgaria. The methodology proposed, based primarily on archive data, represents an effective approach with significant results, especially for the intensive urbanized town territories located in high seismic areas.

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Chai, Chengping, Omar Marcillo, Monica Maceira, Junghyun Park, Stephen Arrowsmith, James O. Thomas et Joshua Cunningham. « Exploring Continuous Seismic Data at an Industry Facility Using Unsupervised Machine Learning ». Seismic Record 5, n^o 1 (1 janvier 2025) : 64–72. https://doi.org/10.1785/0320240046.

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Abstract Seismic data recorded at industrial sites contain valuable information on anthropogenic activities. With advances in machine learning and computing power, new opportunities have emerged to explore the seismic wavefield in these complex environments. We applied two unsupervised machine learning algorithms to analyze continuous seismic data collected from an industrial facility in Texas, United States. The Uniform Manifold Approximation and Projection for Dimension Reduction algorithm was used to reduce the dimensionality of the data and generate 2D embeddings. Then, the Hierarchical Density-Based Spatial Clustering of Applications with Noise method was employed to automatically group these embeddings into distinct signal clusters. Our analysis of over 1400 hr (around 59 days) of continuous seismic data revealed five and seven signal clusters at two separate stations. At both stations, we identified clusters associated with background noise and vehicle traffic, with the latter’s temporal patterns aligning closely with the facility’s work schedule. Furthermore, the algorithms detected signal clusters from unknown sources and underline the ability of unsupervised machine learning for uncovering previously unrecognized patterns. Our analysis demonstrates the effectiveness of unsupervised approaches in examining continuous seismic data without requiring prior knowledge or pre-existing labels.

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Inbal, Asaf. « Forensic Seismic Evidence for Precursory Mobilization in Gaza Leading to the October 7 Hamas Attack ». Seismic Record 4, n^o 4 (1 octobre 2024) : 288–98. http://dx.doi.org/10.1785/0320240018.

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Abstract This study analyzes the seismic noise wavefield recorded before the October 7 Hamas attack on Israel. Preattack activity involved large-scale mobilization, as was documented by various media sources. Opportune conditions stemming from a temporary reduction in Israeli anthropogenic activity enabled the identification of signals generated by vehicular movement in Gaza at three regional seismic stations. Seismogram analysis reveals a widespread signal that abruptly emerged above the nighttime noise levels about 20 min before the attack began. Previous Saturday mornings did not exhibit interstation correlations and signal amplitudes as high as the ones observed on the three stations in the minutes before the attack began. Statistical analysis suggests the October 7 preattack signal is highly anomalous and unlikely to emerge by chance. Tripartite array analysis was used to detect surface waves, locate their sources, and demarcate the extent of preattack activity within the Gaza Strip. The signal’s amplitude, frequency, and spatiotemporal distribution appear to be aligned with vehicular traffic emanating from the south-central region of the Gaza Strip and extending toward its peripheries in the half-hour window preceding the invasion. This analysis underscores the potential utility of seismic noise measurements in identifying large-scale terrorist vehicular mobilizations in advance.

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Lakhnarayan Kumar Bhagarathi, Phillip N. B. DaSilva, Gyanpriya Maharaj, Rahaman Balkarran et Aarif Baksh. « The impact of anthropogenic sound on marine mammals : A review ». International Journal of Life Science Research Archive 7, n^o 2 (30 octobre 2024) : 009–33. http://dx.doi.org/10.53771/ijlsra.2024.7.2.0070.

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This paper aims to review and evaluate published literature on the impact of anthropogenic sound on marine mammals. A systematic method was utilized to access research works of literature on “Impact of Anthropogenic Sound on Marine Mammals”. A total of seventy-seven (77) research papers published between the years 1959 to 2022 were accumulated and used for this review. A subjective approach was used to select the topics: impact of anthropogenic sound and marine mammals. In this paper, six (6) detrimental impacts of anthropogenic sound on marine mammals were evaluated and presented. Anthropogenic sounds originate from a variety of sources such as explosions, commercial shipping, seismic exploration, sonar, research sound source, acoustic deterrent devices and pingers, polar icebreakers, industrial activities, offshore drilling, construction, small ships, boats, and personal watercraft. Among the main impacts identified were that anthropogenic sounds affect marine mammals by causing hearing loss, masking, change in behavior, habituation shift and mass stranding. A mini checklist of several species of marine mammals and different types of anthropogenic noise that affect them are presented. Marine mammals are capable of self-generating their own sounds and they are also affected by anthropogenic sounds that are not native to their natural environments. The published literature that was reviewed established that the global marine mammal population dynamics, abundance, distribution, navigation, ecology and behavior are all affected by anthropogenic sounds. This review highlights the fact that more extensive studies on the impact of anthropogenic sound on marine mammals should be done in neotropical countries since there are gaps of such information on research and published data in these biodiversity-rich regions.

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Erbe, Christine, Renee P. Schoeman, David Peel et Joshua N. Smith. « It Often Howls More than It Chugs : Wind versus Ship Noise Under Water in Australia’s Maritime Regions ». Journal of Marine Science and Engineering 9, n^o 5 (27 avril 2021) : 472. http://dx.doi.org/10.3390/jmse9050472.

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Marine soundscapes consist of cumulative contributions by diverse sources of sound grouped into: physical (e.g., wind), biological (e.g., fish), and anthropogenic (e.g., shipping)—each with unique spatial, temporal, and frequency characteristics. In terms of anthropophony, shipping has been found to be the greatest (ubiquitous and continuous) contributor of low-frequency underwater noise in several northern hemisphere soundscapes. Our aim was to develop a model for ship noise in Australian waters, which could be used by industry and government to manage marine zones, their usage, stressors, and potential impacts. We also modelled wind noise under water to provide context to the contribution of ship noise. The models were validated with underwater recordings from 25 sites. As expected, there was good congruence when shipping or wind were the dominant sources. However, there was less agreement when other anthropogenic or biological sources were present (i.e., primarily marine seismic surveying and whales). Off Australia, pristine marine soundscapes (based on the dominance of natural, biological and physical sound) remain, in particular, near offshore reefs and islands. Strong wind noise dominates along the southern Australian coast. Underwater shipping noise dominates only in certain areas, along the eastern seaboard and on the northwest shelf, close to shipping lanes.

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Saadia, Benjamin, et Georgia Fotopoulos. « Characterizing Ambient Seismic Noise in an Urban Park Environment ». Sensors 23, n^o 5 (22 février 2023) : 2446. http://dx.doi.org/10.3390/s23052446.

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In this study, a method for characterizing ambient seismic noise in an urban park using a pair of Tromino3G+ seismographs simultaneously recording high-gain velocity along two axes (north-south and east-west) is presented. The motivation for this study is to provide design parameters for seismic surveys conducted at a site prior to the installation of long-term permanent seismographs. Ambient seismic noise refers to the coherent component of the measured signal that comes from uncontrolled, or passive sources (natural and anthropogenic). Applications of interest include geotechnical studies, modeling the seismic response of infrastructure, surface monitoring, noise mitigation, and urban activity monitoring, which may exploit the use of well-distributed seismograph stations within an area of interest, recording on a days-to-years scale. An ideal well-distributed array of seismographs may not be feasible for all sites and therefore, it is important to identify means for characterizing the ambient seismic noise in urban environments and limitations imposed with a reduced spatial distribution of stations, herein two stations. The developed workflow involves a continuous wavelet transform, peak detection, and event characterization. Events are classified by amplitude, frequency, occurrence time, source azimuth relative to the seismograph, duration, and bandwidth. Depending on the applications, results can guide seismograph selection (sampling frequency and sensitivity) and seismograph placement within the area of interest.

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Lee, Jung-Han, Sung-Hyub Ko, Seom-Kyu Jung et Jong-Wu Hyeon. « Tertiary Waves Measured during 2017 Pohang Earthquake Using an Underwater Glider ». Applied Sciences 9, n^o 18 (14 septembre 2019) : 3860. http://dx.doi.org/10.3390/app9183860.

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An underwater glider equipped with a hydrophone observed the acoustic sounds of an earthquake that occurred on 15 November 2017 05:29:32 (UTC) in the Pohang area. The underwater glider observed the earthquake sounds after 19 s (05:29:51) at approximately 140 km from the Pohang epicenter. In order to distinguish the earthquake sound from the glider’s operation noise, the noise sources and Sound Pressure Level (SPL) of the underwater glider were analyzed and measured at laboratory tank and sea. The earthquake acoustic signal was distinguished from glider’s self-noises of fin, pumped Conductivity-Temperature-Depth profiler (CTD) and altimeter which exist over 100 Hz. The dominant frequencies of the earthquake acoustic signals due to the earthquake were 10 Hz. Frequencies at which the spectra had dropped 60 dB were 50 Hz. By analysis of time correlation with seismic waves detected by five seismic land stations and the earthquake acoustic signal, it is clearly shown that the seismic waves converted to Tertiary waves and then detected by the underwater glider. The results allow constraining the acoustic sound level of the earthquake and suggest that the glider provides an effective platform for enhancing the earth seismic observation systems and monitoring natural and anthropogenic ocean sounds.

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Popper, Arthur N., Jane Fewtrell, Michael E. Smith et Robert D. McCauley. « Anthropogenic Sound : Effects on the Behavior and Physiology of Fishes ». Marine Technology Society Journal 37, n^o 4 (1 décembre 2003) : 35–40. http://dx.doi.org/10.4031/002533203787537050.

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Anthropogenic sound in the marine environment continues to increase. Sound sources range from increased vessel traffic to transient but intense sounds such as those produced by seismic air guns, pile driving, or some sonars. While most interest in anthropogenic sounds has focused on marine mammals, there is an increasing concern regarding the impact of such sounds on fishes and marine invertebrates. Since the inner ear hearing receptors of fishes are similar to those of marine mammals, any effects seen on the hearing receptors of marine mammals may also be found in fishes and vice versa. Despite increasing interest in the effects of sounds on fishes, this issue has only been addressed on the most limited scale. Here we review the current literature in this area. It has been reported that high sound levels can damage the inner ear sensory cells, produce hearing loss (threshold shifts), elicit stress responses, and alter the behavior of fishes. At least in terms of hearing loss, these effects are modulated by exposure sound level and duration. The effects of various types of sound (e.g., impulsive vs. continuous) and long-term impacts of how anthropogenic sounds affect the behavior and ecology of fishes need exploration in the future.

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Koley, Soumen, Maria Bader, Jo van den Brand, Xander Campman, Henk Jan Bulten, Frank Linde et Bjorn Vink. « Surface and underground seismic characterization at Terziet in Limburg—the Euregio Meuse–Rhine candidate site for Einstein Telescope ». Classical and Quantum Gravity 39, n^o 2 (11 janvier 2022) : 025008. http://dx.doi.org/10.1088/1361-6382/ac2b08.

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Abstract We present a detailed characterization of surface and underground seismic noise measured at Limburg in the south of the Netherlands. This location is the Euregio Meuse–Rhine candidate for hosting Einstein Telescope, a future observatory for gravitational waves. Seismic noise measurements were performed with an array of seismometers installed on the surface. Passive seismic methods like beamforming were used to extract the propagation wave types of ambient seismic noise and the Rayleigh-wave dispersion in the region. Subsurface shear-wave models sensitive to depths of 300 m were derived by using the Rayleigh-wave dispersion and ellipticity. Subsurface P-wave velocities to depths of 200 m were obtained from an active seismic survey. Wavepath Eikonal tomography was used on the source-receiver refracted-wave travel-times to obtain a subsurface P-wave velocity model. Both the passive and the active seismic data analysis point to the presence of a layered geology with a soft-soil to hard-rock transition occurring at a shallow depth of about 25 to 40 m. The surface arrays are complemented by two permanent tri-axial seismometers installed on the surface and in a borehole at 250 m depth. Their data are used to interpret the surface-wave and body-wave contributions to the observed seismic noise. We use a cross-correlation analysis and compute the theoretical surface-wave eigenfunctions to understand the contributions of the different wave types at different frequencies. We observe that below 4 Hz in the horizontal component and 9 Hz in the vertical component, the seismic noise at depth is dominantly due to surface waves. Above these frequencies a significant contribution can be attributed to both nearby and far-away body-wave sources. At a depth of 250 m we find that the surface noise power has been damped by up to a factor 104 above about 2 Hz. The Limburg geology with soft-soil on top of hard-rock efficiently damps the anthropogenic noise produced at the surface. This implies that Einstein Telescope’s test masses are shielded from anthropogenic seismic noise and construction at greater depth will not bring significant further improvements in this regard. A body-wave background has been identified that contributes about half of the total underground seismic noise at 250 m depth for frequencies above 4 Hz. It remains to be studied if subtraction schemes for Newtonian noise originating from this body-wave background will be necessary. Finally, we estimate an interferometer downtime of about 3% due to regional and teleseismic earthquakes. We believe this is acceptable as it is comparable to current experience at the LIGO and Virgo interferometer sites.

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van Wijk, Kasper, Calum J. Chamberlain, Thomas Lecocq et Koen Van Noten. « Seismic monitoring of the Auckland Volcanic Field during New Zealand's COVID-19 lockdown ». Solid Earth 12, n^o 2 (9 février 2021) : 363–73. http://dx.doi.org/10.5194/se-12-363-2021.

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Abstract. The city of Auckland, New Zealand (Tāmaki Makaurau, Aotearoa), sits on top of an active volcanic field. Seismic stations in and around the city monitor activity of the Auckland Volcanic Field (AVF) and provide data to image its subsurface. The seismic sensors – some positioned at the surface and others in boreholes – are generally noisier during the day than during nighttime. For most stations, weekdays are noisier than weekends, proving human activity contributes to recordings of seismic noise, even on seismographs as deep as 384 m below the surface and as far as 15 km from Auckland's Central Business District. Lockdown measures in New Zealand to battle the spread of COVID-19 allow us to separate sources of seismic energy and evaluate both the quality of the monitoring network and the level of local seismicity. A matched-filtering scheme based on template matching with known earthquakes improved the existing catalogue of five known local earthquakes to 35 for the period between 1 November 2019 and 15 June 2020. However, the Level-4 lockdown from 25 March to 27 April – with its drop in anthropogenic seismic noise above 1 Hz – did not mark an enhanced detection level. Nevertheless, it may be that wind and ocean swell mask the presence of weak local seismicity, particularly near surface-mounted seismographs in the Hauraki Gulf that show much higher levels of noise than the rest of the local network.

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Kovachev, S. A., et A. A. Krylov. « Results of Seismological Monitoring in the Baltic Sea and Western Part of the Kaliningrad Oblast Using Bottom Seismographs ». Физика земли 2023, n^o 2 (1 mars 2023) : 94–114. http://dx.doi.org/10.31857/s0002333723020072.

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In 2007–2015, Shirshov Institute of Oceanology of the Russian Academy of Sciences (IO RAS) carried out seismological observations in the water area and on the coast of the Baltic Sea using autonomous seismic stations. Here, in the area of the Sambia Peninsula, previously considered aseismic, a strong perceptible earthquake with a magnitude of about M = 4.6 occurred in 2004. The most interesting data were obtained by IO RAS in 2008–2009 from seismological monitoring using autonomous bottom and coastal seismic stations. The data obtained in 2010–2015 turned out to be unsuitable for full-scope processing due to several causes (losses of bottom seismographs, high noise level at coastal stations, etc.). Seismological monitoring in the west of the Kaliningrad region and in the adjoining area of the Baltic Sea detected weak earthquakes with magnitudes ML = 2.5-3 whose sources are confined to the development are of the Kravtsovskoe offshore oil field. Some of these earthquakes have been recorded by the stations of the Norwegian seismic array NORSAR and by the seismic stations of Sweden. The Kravtsovskoe oil field is located on the shelf northwest of the unique natural object, the Curonian Spit. The detected weak earthquakes are likely to be anthropogenic, induced by reservoir pressure disturbances as a result of intensive hydrocarbon production, and are probably precursors of a strong man-made earthquake.

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Meng, Haoran, Yehuda Ben-Zion et Christopher W. Johnson. « Analysis of Seismic Signals Generated by Vehicle Traffic with Application to Derivation of Subsurface Q-Values ». Seismological Research Letters 92, n^o 4 (24 février 2021) : 2354–63. http://dx.doi.org/10.1785/0220200457.

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Abstract Correct identification and modeling of anthropogenic sources of ground motion are of considerable importance for many studies, including detection of small earthquakes and imaging seismic properties below the surface. To understand signals generated by common vehicle traffic, we use seismic data recorded by closely spaced geophones normal to roads at two sites on San Jacinto fault zone. To quantify the spatiotemporal and frequency variations of the recorded ground motions, we develop a simple analytical solution accounting for propagation and attenuation of surface waves. The model reproduces well-observed bell-shaped spectrograms of car signals recorded by geophones close to roads, and it can be used to estimate frequency-dependent Q-values of the subsurface materials. The data analysis indicates Q-values of 3–40, for frequencies up to 150 Hz for road-receiver paths at the two examined sites. The derived Q-values are consistent with attenuation factors of surface waves previously obtained with other methods. The analytical results and analysis procedure provide a highly efficient method for deriving Q-values of shallow subsurface materials.

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Verbytskyi, Serhii, Bohdan Kuplovskyi, Vasyl Prokopyshyn, Oleksandr Stetskiv, Iryna Nishchimenko, Taras Brych et Oleh Kruk. « GEODYNAMICS ». GEODYNAMICS 1(30)2021, n^o 1(30) (29 juin 2021) : 58–64. http://dx.doi.org/10.23939/jgd2021.01.058.

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Objective. To refine seismic hazard parameters by registering high-frequency microseisms within the site under reconstruction in connection with the land plot enlargement of a plant intended for electronic components manufacturing. To quantify the estimated intensity of seismic shakings (in MSK-64 scale scores) accounting for the effects associated with local engineering and geological conditions at the study site. Methods. Seismic microzonation practical works at construction sites implies the application of short-period microseism registration method, which is considered to be one of the most efficient and unbiased instrumental SMZ methods when the field seismological studies are to be performed in a short period of time. The method relies on comparing parameters of soil micro-vibrations generated by natural and anthropogenic sources at the studied and the reference sites. At that, the soil is regarded as a filter capable of modifying the amplitude and phase oscillation spectra of seismic waves hitting the sedimentary cover basement. The seismic intensity gains were determined by comparing the amplitudes of soil oscillations at registration points over several sections of the site and at a reference point. Microseisms were recorded by using two identical three-channel digital seismic stations DAS-05 being the newest ones out of the model series of automatic seismic stations developed at S. I. Subbotin Institute of Geophysics of the NAS of Ukraine. VEGIK seismometers were used as seismometers. Results. Microseismic oscillation recording analysis has revealed that the main contribution to the formation of a wave field is due to the urban background disturbances falling within the frequency range of f = 8.0 - 18.0 Hz, as well as low-frequency natural oceanic effects amounting to f = 0.4 - 8.0 Hz while high-frequency vibrations are caused by anthropogenic factors amounting to f = 18.0 - 27.0 Hz (Fig. 3). Data of synchronous 24-hour microseism registering have indicated a sufficiently high stability of the amplitude level and frequency composition of microseismic oscillations, which suggests that the microseismic processes approximate stationary ones, provided that non-stationary events are removed from records. Plots of seismic intensity gain values at different frequencies caused by soil conditions at the studied site, determined according to the relation of averaged microseismic amplitude spectra both at the studied and reference site, are shown in Fig. 4. The average estimates of seismic intensity gains in the frequency range of 0.1 - 20.0 Hz for the construction site soil conditions, calculated with respect to microseismic spectral densities per all three vibration components, are presented in Table 1. The seismic intensity gain in relation to the initial (background) one for the engineering and geological conditions of the site equals to ΔIr = -0.21. Scientific novelty. Given the amplitude ratio and amplitude spectra of microseisms recorded at different sites and at the reference point, refined parameters of seismic hazards for the developable site have been obtained with consideration of the local soil conditions effects. Evaluation ratings of seismic shaking calculated intensity (in MSK-64 scale scores) based on effects associated with the local engineering and geological conditions of the study site have been provided. Practical significance. Construction site SMZ yields updated values of seismic forces relative to the general seismic zonation of the country, which allows taking into account possible gain in seismic severity at the design stage of earthquake-proof construction. Consideration of SMZ results at construction of engineering structures prevents human casualties and reduces economic losses in case of seismic manifestations.

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Weilgart, L. S. « The impacts of anthropogenic ocean noise on cetaceans and implications for management ». Canadian Journal of Zoology 85, n^o 11 (novembre 2007) : 1091–116. http://dx.doi.org/10.1139/z07-101.

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Ocean noise pollution is of special concern for cetaceans, as they are highly dependent on sound as their principal sense. Sound travels very efficiently underwater, so the potential area impacted can be thousands of square kilometres or more. The principal anthropogenic noise sources are underwater explosions (nuclear and otherwise), shipping, seismic exploration by mainly the oil and gas industries, and naval sonar operations. Strandings and mortalities of especially beaked whales (family Ziphiidae) have in many cases been conclusively linked to noise events such as naval maneuvers involving tactical sonars or seismic surveys, though other cetacean species may also be involved. The mechanisms behind this mortality are still unknown, but are most likely related to gas and fat emboli at least partially mediated by a behavioral response, such as a change in diving pattern. Estimated received sound levels in these events are typically not high enough to cause hearing damage, implying that the auditory system may not always be the best indicator for noise impacts. Beaked whales are found in small, possibly genetically isolated, local populations that are resident year-round. Thus, even transient and localized acoustic impacts can have prolonged and serious population consequences, as may have occurred following at least one stranding. Populations may also be threatened by noise through reactions such as increased stress levels, abandonment of important habitat, and “masking” or the obscuring of natural sounds. Documented changes in vocal behavior may lead to reductions in foraging efficiency or mating opportunities. Responses are highly variable between species, age classes, behavioral states, etc., making extrapolations problematic. Also, short-term responses may not be good proxies of long-term population-level impacts. There are many examples of apparent tolerance of noise by cetaceans, however. Noise can also affect cetaceans indirectly through their prey. Fish show permanent and temporary hearing loss, reduced catch rates, stress, and behavioral reactions to noise. Management implications of noise impacts include difficulties in establishing “safe” exposure levels, shortcomings of some mitigation tools, the need for precaution in the form of reducing noise levels and distancing noise from biologically important areas, and the role of marine protected areas and monitoring in safeguarding cetaceans especially from cumulative and synergistic effects.

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Loginov, Dmitriy S. « Interpretation and origin determination of oil seepages using marine seismic data : a case study of the Western Continental Margin of India ». Geoinformatika, n^o 1 (27 mars 2024) : 55–67. http://dx.doi.org/10.47148/1609-364x-2024-1-55-67.

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This article discusses the experience of a joint using remote sensing data, marine seismic data and open geoscientific data to search for natural mineral oil seepages. The study was carried out as part of an assessment of oil prospects in the offshore sedimentary basins of the Arabian Sea on the west coast of the Indian Peninsula. The methodology is based on visual interpretation of natural and anthropogenic oil seepages using Sentinel-2 multispectral imageries. Modern offshore seismic data is used to establish the mineral origin of oil seepages by the presence of reservoirs and fault systems as possible sources of hydrocarbons and channels for their migration to the surface, respectively. The final map of detected oil seepages location is the result of research. Areas of natural mineral oil seepages accumulation confined to the western continental margin of India have been identified. Recommendations for exploration activities in the Kutch, Saurashtra and Kerala-Konkan offshore sedimentary basins were given. The acquired experience of visual interpretation of multispectral satellite data confirms efficiency of marine seismic data application for delineation of natural oil seepages of mineral origin in the areas of intensive navigation. The proposed methodology of research can be used as an indirect assessment of oil prospects in the Western Continental Margin of India and other areas of the world ocean.

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Dahl, Peter H., Julien Bonnel et David R. Dall'Osto. « On the equivalence of scalar-pressure and vector-based acoustic dosage measures as derived from time-limited signal waveforms ». Journal of the Acoustical Society of America 155, n^o 5 (1 mai 2024) : 3291–301. http://dx.doi.org/10.1121/10.0026019.

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The dynamic (acoustic pressure) and kinematic (acoustic acceleration and velocity) properties of time-limited signals are studied in terms of acoustic dose metrics as might be used to assess the impact of underwater noise on marine life. The work is relevant for the study of anthropogenic transient acoustic signals, such as airguns, pile driving, and underwater explosive sources, as well as more generic transient signals from sonar systems. Dose metrics are first derived from numerical simulations of sound propagation from a seismic airgun source as specified in a Joint Industry Programme benchmark problem. Similar analyses are carried out based on at-sea acoustic measurements on the continental shelf, made with a vector sensor positioned 1.45 m off the seabed. These measurements are on transient time-limited signals from multiple underwater explosive sources at differing ranges, and from a towed, sonar source. The study demonstrates, both numerically and experimentally, that under many realistic scenarios, kinematic based acoustic dosage metrics within the water column can be evaluated using acoustic pressure measurements.

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Correa, Julia, Aleksei Titov et Vladimir Kazei. « Introduction to this special section : Geophysics and sustainability ». Leading Edge 43, n^o 8 (août 2024) : 482. http://dx.doi.org/10.1190/tle43080482.1.

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Unprecedented levels of greenhouse gasses in the atmosphere drive climate change by trapping heat and raising global temperatures. This warming effect disrupts weather patterns, increases the frequency of natural disasters, and contributes to rising sea levels. Applied geophysics can significantly alleviate anthropogenic emissions and accelerate the transition to cleaner energy sources such as wind, solar, geothermal energy, and hydrogen. One solution at the core of energy transition is the broad application of carbon capture, utilization, and geologic storage (CCUS) at the scale of gigatonnes of sequestered CO2 to reduce greenhouse gas emissions during the transition to a carbon-neutral future. Geophysical monitoring is central to the success of CCUS. In particular, seismic methods serve as a primary tool to ensure compliance and safety in CCUS projects. However, the role of geophysics in sustainability is a broader topic extending beyond carbon geosequestration.

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Hoggard, Mark J., Janice L. Scealy et Brent G. Delbridge. « Seismic moment tensor classification using elliptical distribution functions on the hypersphere ». Geophysical Journal International 237, n^o 1 (2 février 2024) : 1–13. http://dx.doi.org/10.1093/gji/ggae011.

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SUMMARY Discrimination of underground explosions from naturally occurring earthquakes and other anthropogenic sources is one of the fundamental challenges of nuclear explosion monitoring. In an operational setting, the number of events that can be thoroughly investigated by analysts is limited by available resources. The capability to rapidly screen out events that can be robustly identified as not being explosions is, therefore, of great potential benefit. Nevertheless, possible mis-classification of explosions as earthquakes currently limits the use of screening methods for verification of test-ban treaties. Moment tensors provide a physics-based classification tool for the characterization of different seismic sources and have enabled the advent of new techniques for discriminating between earthquakes and explosions. Following normalization and projection of their six-degree vectors onto the hypersphere, existing screening approaches use spherically symmetric metrics to determine whether any new moment tensor may have been an explosion. Here, we show that populations of moment tensors for both earthquakes and explosions are anisotropically distributed on the hypersphere. Distributions possessing elliptical symmetry, such as the scaled von Mises–Fisher distribution, therefore provide a better description of these populations than the existing spherically symmetric models. We describe a method that uses these elliptical distributions in combination with a Bayesian classifier to achieve successful classification rates of 99 per cent for explosions and 98 per cent for earthquakes using existing catalogues of events from the western United States. The 1983 May 5 Crowdie underground nuclear test and 2018 July 20 DAG-1 deep-borehole chemical explosion are the only two explosions out of 140 that are incorrectly classified. Application of the method to the 2006–2017 nuclear tests in the Democratic People’s Republic of Korea yields 100 per cent identification rates and we provide a simple routine MTid for general usage. The approach provides a means to rapidly assess the likelihood of an event being an explosion and can be built into monitoring workflows that rely on simultaneously assessing multiple different discrimination metrics.

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Velasco, Marco. « Estimation of ambient marine noise levels in New South Wales ». Journal of the Acoustical Society of America 154, n^o 4_supplement (1 octobre 2023) : A310. http://dx.doi.org/10.1121/10.0023632.

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Marine and offshore infrastructure is increasingly becoming more prominent in NSW resulting in a requirement to investigate the potential behavioral and physiological impacts to marine fauna during construction and operational phases. Typically, detailed modeling is undertaken to compare the predicted underwater noise levels against noise thresholds with limited consideration to the existing ambient noise levels specific to the site. Vessel movements are known to be the primary contributor to ambient underwater noise levels from anthropogenic sources whereas prevailing noise is generally dominated by natural sources such as wind, waves, precipitation, and seismic activity. Underwater noise monitoring of baseline conditions is not always feasible and can also be cost-prohibitive to undertake. Additionally, there is currently limited publicly available underwater noise measurement data along the eastern coastline of NSW, specifically in shallow waters at depths less than 50 m. This study includes simple procedures to allow for preliminary estimates of the key contributors to the marine noise environment in the context of the Eastern coastline of NSW, with the aim of producing maps estimating existing marine noise levels for common descriptors such as SPL(rms) and SEL(24hour).

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van Ginkel, Janneke, Fabian Walter, Fabian Lindner, Miroslav Hallo, Matthias Huss et Donat Fäh. « Spectral characteristics of seismic ambient vibrations reveal changes in the subglacial environment of Glacier de la Plaine Morte, Switzerland ». Cryosphere 19, n^o 3 (1 avril 2025) : 1469–90. https://doi.org/10.5194/tc-19-1469-2025.

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Abstract. Glaciers exhibit complex hydraulic and dynamic behaviour that needs to be studied to enhance our understanding of cryospheric changes. To address this, we apply a range of passive seismic analysis techniques to continuous data from a temporary seismic array deployed on Glacier de la Plaine Morte, Switzerland. First, we assess the reliability of ambient noise horizontal-to-vertical spectral ratio (HVSR) measurements and demonstrate that the variations in HVSR curves are predominantly attributed to changing nearby noise conditions influenced by hydraulic, drainage-related tremors, moulin resonances, and anthropogenic sources. We find that short time series (e.g. hours-long) may lead to biases in the interpretation of the HVSR curve. Hence, we perform an analysis of the local noise source variations related to glacier dynamic behaviour in order to distinguish between source and medium changes reflected in the HVSR measurements. In 130 d long time series of measurements we are able to detect a spatio-temporal trend and find that an HVSR trough emerges following the sudden drainage of an ice-marginal lake. This HVSR trough is indicative of a low-seismic-velocity layer at the ice–bed interface. Seismic velocity changes derived by interferometry support our findings of a velocity drop in the glacier after the drainage. Subsequently, inversion and forward modelling of the empirical dispersion and ellipticity curves reveal a probable thickness of this low-velocity layer of 10–30 m and a change in shear-wave velocity up to 40 %. This layer has a local extent covering an estimated 4.5 % to 27 % of the glacier, as indicated by the spatial variations in the HVSR trough throughout the array and an independent water volume estimate. Our findings suggest that the changing seismic velocities are a manifestation of temporal subglacial water storage in response to the sudden injection of lake water. Our results highlight the value of long time series of HVSR measurements which show variations in the peak and trough structure that reflect hydrological changes in the subglacial environment.

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Aliyev, E. M., S. A. Guryanov et A. S. Belyaeva. « Current geological processes affecting the environment of the Caspian region ». Proceedings of higher educational establishments. Geology and Exploration 66, n^o 3 (9 novembre 2024) : 107–26. http://dx.doi.org/10.32454/0016-7762-2024-66-3-107-126.

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Background. In addition to anthropogenic activities affecting the environment, geological hazards pose significant risks to the natural environment, as well as to human population, buildings, and infrastructure. In the Caspian region, geological hazards are primarily associated with geodynamic activity and dissipation of fluid-dynamic stress within the hydro- and lithodynamic flow systems in the subsurface, which manifests in the form of intense upward flows of mobile fluids that significantly impact the surrounding environment. Aim. To investigate and assess the current geological processes affecting the environment of the Caspian region. Materials and methods. The computer processing and visual interpretation of radar information, as well as the data of marine geological-geophysical and seismic studies, revealed correlation of oil slicks and gas emissions with the sources of fluid generation and discharge within the sedimentary cover of the Caspian region. The correlation between the occurrence of oil slicks and regional seismic activity was evaluated using data from the USGS National Earthquake Information Center concerning earthquakes in the Southern Caspian region. Results. The conducted studies evaluated the scale of current geological processes that affect the environment of the Caspian region. In addition to anthropogenic degassing, the role of deep and crustal degassing of the Earth has been found significant in this region. Natural oil and gas showings are spatially and genetically linked primarily with geological processes—vertical and horizontal movements, seismicity, including sedimentary—small-focus seismicity, mud volcanism, the migration and emigration of hydrocarbons, as well as the accumulation of free gas in the upper part of the sedimentary sequence. Conclusion. Crustal degassing is associated with the state and functioning of geofluid-dynamic systems, evolving and developing under the influence of geodynamic processes throughout the sedimentary filling at all stages of the basin’s evolution, with the active contributions of the generation and migration of methane, hydrogen, and other gases. Discharges of oil and gas in water exhibit significant variability, including local (concentrated) discharges (such as mud volcanoes, gas seeps, salt springs, slicks, and others), widespread hydrocarbon influx and its fractions from petroleum and gas-bearing structures via faults. Oil pollution in Baku Bay appears to be a consequence of natural fluid dynamic processes occurring in its subsurface. The sources of oil slicks refer to the areas where formation fluids are discharged in the sedimentary cover structures. The discharge is influenced by the seismicity of the Earth’s crust in the South Caspian tectonic basin.

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Howe, Bruce M., et James H. Miller. « Acoustic Sensing for Ocean Research ». Marine Technology Society Journal 38, n^o 2 (1 juin 2004) : 144–54. http://dx.doi.org/10.4031/002533204787522811.

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Ocean observatories have the potential to examine the physical, chemical, biological, and geological parameters and processes of the ocean at time and space scales previously unexplored. Acoustics provides an efficient and cost-effective means by which these parameters and processes can be measured and information can be communicated. Integrated acoustics systems providing navigation and communications and conducting acoustic measurements in support of science applications are, in concept, analogous to the Global Positioning System, but rely on acoustics because the ocean is opaque to electromagnetic waves and transparent to sound. A series of nested systems is envisioned, from small- to regional- to basin-scale. A small number of acoustic sources sending coded, low power signals can service unlimited numbers of inexpensive receivers. Drifting and fixed receivers can be tracked accurately while collecting ocean circulation and heat content data (both point and integral data), as well as ambient sound data about wind, rain, marine mammals, seismic T-phases, and anthropogenic activity. The sources can also transmit control data from users to remote instruments, and if paired with receivers enable two-way acoustic communications links. Acoustic instrumentation that shares the acoustic spectrum completes the concept of integrated acoustics systems. The ocean observations presently in the planning and implementation stages will require these integrated acoustics systems.

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André, Michel. « Ocean noise : Making sense of sounds ». Social Science Information 57, n^o 3 (21 août 2018) : 483–93. http://dx.doi.org/10.1177/0539018418793052.

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The growing scientific and societal concern about the effects of underwater sound on marine ecosystems has recently been recognized through the introduction of several international initiatives aimed at measuring the environmental impact of ocean noise on large spatial and temporal scales. From a regulatory perspective, the European Marine Strategy Framework Directive includes noise as one of 11 descriptors to determine Good Environmental Status of the oceans. The Directive specifically requires European Union (EU) Member States to provide a measure of annually averaged noise. The international program LIDO (Listening to the Deep-Ocean Environment) has developed a software package that measures sound levels and monitors acoustic sources in real-time on a global scale; this software is now operating to provide industry with an environmentally responsible approach. The system is currently operating worldwide from several wired and radio- or satellite-linked platforms. It includes the automatic identification of acoustic events (physical processes, biological sounds and artificial noise) and the measurement of noise contributions from anthropogenic sources. Continuous monitoring of background noise will indeed help us to understand whether long-term exposures to noise, in areas with intense shipping or seismic campaigns, for instance, might alter animal natural behaviour and may be used in the future to assess the effects of ocean noise on marine life.

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Insley, Stephen J., William D. Halliday et Tyler De Jong. « Seasonal Patterns in Ocean Ambient Noise near Sachs Harbour, Northwest Territories + Supplementary Appendix 1 (See Article Tools) ». ARCTIC 70, n^o 3 (3 septembre 2017) : 239. http://dx.doi.org/10.14430/arctic4662.

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Ocean ambient noise is a crucial habitat feature for marine animals because it represents the lower threshold of their acoustically active space. Ambient noise is affected by noise from both natural sources, like wind and ice, and anthropogenic sources, such as shipping and seismic surveys. During the ice-covered season, ambient conditions in the Arctic are quieter than those in other regions because sea ice has a dampening effect. Arctic warming induced by climate change can raise noise levels by reducing sea ice coverage and increasing human activity, and these changes may negatively affect several species of marine mammals and other acoustically sensitive marine fauna. We document ambient noise off the west coast of Banks Island near Sachs Harbour, Northwest Territories, to provide baseline noise levels for the eastern Beaufort Sea. Noise levels were comparable to those found in other studies of the Canadian Arctic and Alaska and were typically much lower than levels reported farther south. Stronger wind increased noise, whereas greater ice concentration decreased it, dampening the effect of wind speed. Future work should expand monitoring to other locations in the Arctic, model the impact of increased human activities on ambient noise levels, and predict the impact of these changing levels on marine animals.

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Ali, Mohammed Y., Braham Barkat, Karl A. Berteussen et James Small. « A low-frequency passive seismic array experiment over an onshore oil field in Abu Dhabi, United Arab Emirates ». GEOPHYSICS 78, n^o 4 (1 juillet 2013) : B159—B176. http://dx.doi.org/10.1190/geo2012-0054.1.

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A low-frequency passive seismic experiment using an array of 49 3C broadband seismometers was conducted over an onshore oil field in the emirate of Abu Dhabi in the United Arab Emirates. The aim of the experiment was to understand the characteristics and origins of the microseism (0.15–0.4 Hz) and microtremor (about 1–6 Hz) signals recorded, the latter having been reported as being a hydrocarbon indicator above several reservoirs in the region. The recorded array data were analyzed for their polarization, apparent velocities, and wavefront azimuths using various techniques, including spectral and time-frequency analyses, particle motion, H/V spectral ratios, and high-resolution frequency-wavenumber (f-k) analyses. In the frequency range of 0.15–0.4 Hz, the dominant feature observed consisted of double-frequency microseisms peaks generated by the nonlinear interactions of ocean waves with the shoreline along the coasts of the Arabian Sea and the Arabian Gulf. The f-k analyses confirmed that microtremor events in the frequency range of 2–3 Hz have an azimuth pointing toward a major oil pipeline and oil plant facilities to the west–southwest of the study area, as well as a motorway to the southeast. This would indicate that the microtremor events are probably caused by local sources, including the continuous movement of oil through the pipeline, the noise from oil plant facilities, as well as nearby traffic noise. This interpretation was confirmed by the polarization analysis performed on the data. The data also indicated that no clear correlation exists between the microtremor signal and local meteorological conditions. Although some body waves with an infinite apparent velocity generated by earthquakes were recorded, no other body waves that could have possibly been generated by hydrocarbon reservoirs were observed using the analyses techniques used in this study. Therefore, our results indicated that for the site under investigation, the microseism and the microtremor signals detected could not be related to the presence of hydrocarbon accumulations in the subsurface, but instead they may be attributed to local anthropogenic sources.

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Meyer, Matthias, Samuel Weber, Jan Beutel et Lothar Thiele. « Systematic identification of external influences in multi-year microseismic recordings using convolutional neural networks ». Earth Surface Dynamics 7, n^o 1 (4 février 2019) : 171–90. http://dx.doi.org/10.5194/esurf-7-171-2019.

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Abstract. Passive monitoring of ground motion can be used for geophysical process analysis and natural hazard assessment. Detecting events in microseismic signals can provide responsive insights into active geophysical processes. However, in the raw signals, microseismic events are superimposed by external influences, for example, anthropogenic or natural noise sources that distort analysis results. In order to be able to perform event-based geophysical analysis with such microseismic data records, it is imperative that negative influence factors can be systematically and efficiently identified, quantified and taken into account. Current identification methods (manual and automatic) are subject to variable quality, inconsistencies or human errors. Moreover, manual methods suffer from their inability to scale to increasing data volumes, an important property when dealing with very large data volumes as in the case of long-term monitoring. In this work, we present a systematic strategy to identify a multitude of external influence sources, characterize and quantify their impact and develop methods for automated identification in microseismic signals. We apply the strategy developed to a real-world, multi-sensor, multi-year microseismic monitoring experiment performed at the Matterhorn Hörnligrat (Switzerland). We develop and present an approach based on convolutional neural networks for microseismic data to detect external influences originating in mountaineers, a major unwanted influence, with an error rate of less than 1 %, 3 times lower than comparable algorithms. Moreover, we present an ensemble classifier for the same task, obtaining an error rate of 0.79 % and an F1 score of 0.9383 by jointly using time-lapse image and microseismic data on an annotated subset of the monitoring data. Applying these classifiers to the whole experimental dataset reveals that approximately one-fourth of events detected by an event detector without such a preprocessing step are not due to seismic activity but due to anthropogenic influences and that time periods with mountaineer activity have a 9 times higher event rate. Due to these findings, we argue that a systematic identification of external influences using a semi-automated approach and machine learning techniques as presented in this paper is a prerequisite for the qualitative and quantitative analysis of long-term monitoring experiments.

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Tibi, Rigobert, Lisa Linville, Christopher Young et Ronald Brogan. « Classification of Local Seismic Events in the Utah Region : A Comparison of Amplitude Ratio Methods with a Spectrogram‐Based Machine Learning Approach ». Bulletin of the Seismological Society of America 109, n^o 6 (22 octobre 2019) : 2532–44. http://dx.doi.org/10.1785/0120190150.

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Abstract The capability to discriminate low‐magnitude earthquakes from low‐yield anthropogenic sources, both detectable only at local distances, is of increasing interest to the event monitoring community. We used a dataset of seismic events in Utah recorded during a 14‐day period (1–14 January 2011) by the University of Utah Seismic Stations network to perform a comparative study of event classification at local scale using amplitude ratio (AR) methods and a machine learning (ML) approach. The event catalog consists of 7377 events with magnitudes MC ranging from −2 and lower up to 5.8. Events were subdivided into six populations based on location and source type: tectonic earthquakes (TEs), mining‐induced events (MIEs), and mining blasts from four known mines (WMB, SMB, LMB, and CQB). The AR approach jointly exploits Pg‐to‐Sg phase ARs and Rg‐to‐Sg spectral ARs in multivariate quadratic discriminant functions and was able to classify 370 events with high signal quality from the three groups with sufficient size (TE, MIE, and SMB). For that subset of the events, the method achieved success rates between about 80% and 90%. The ML approach used trained convolutional neural network (CNN) models to classify the populations. The CNN approach was able to classify the subset of events with accuracies between about 91% and 98%. Because the neural network approach does not have a minimum signal quality requirement, we applied it to the entire event catalog, including the abundant extremely low-magnitude events, and achieved accuracies of about 94%–100%. We compare the AR and ML methodologies using a broad set of criteria and conclude that a major advantage to ML methods is their robustness to low signal‐to‐noise ratio data, allowing them to classify significantly smaller events.

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Albert, Sarah, et Lisa Linville. « Benchmarking Current and Emerging Approaches to Infrasound Signal Classification ». Seismological Research Letters 91, n^o 2A (8 janvier 2020) : 921–29. http://dx.doi.org/10.1785/0220190116.

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Abstract Low-frequency sound ≤20 Hz, known as infrasound, is generated by a variety of natural and anthropogenic sources. Following an event, infrasonic waves travel through a dynamic atmosphere that can change on the order of minutes. This makes infrasound event classification a difficult problem, as waveforms from the same source type can look drastically different. Event classification usually requires ground-truth information from seismic or other methods. This is time consuming, inefficient, and does not allow for classification if the event locates somewhere other than a known source, the location accuracy is poor, or ground truth from seismic data is lacking. Here, we compare the performance of the state of the art for infrasound event classification, support vector machine (SVM) to the performance of a convolutional neural network (CNN), a method that has been proven in tangential fields such as seismology. For a 2-class catalog of only volcanic activity and earthquake events, the fourfold average SVM classification accuracy is 75%, whereas it is 74% when using a CNN. Classification accuracies from the 4-class catalog consisting of the most common infrasound events detected at the global scale are 55% and 56% for the SVM and CNN architectures, respectively. These results demonstrate that using a CNN does not increase performance for infrasound event classification. This suggests that SVM should be the preferred classification method, as it is a simpler and more trustworthy architecture and can be tied to the physical properties of the waveforms. The SVM and CNN algorithms described in this article are not yet generalizable to other infrasound event catalogs. We anticipate this study to be a starting point for development of large and comprehensive, systematically labeled, infrasound event catalogs, as such catalogs will be necessary to provide an increase in the value of deep learning on event classification.

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Lavrova, Olga Yu, Marina I. Mityagina et Andrey G. Kostianoy. « Online database “See The Sea” for the Caspian Sea ». Ecologica Montenegrina 25 (8 novembre 2019) : 79–90. http://dx.doi.org/10.37828/em.2019.25.8.

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For many years, the primary environmental problem of the Caspian Sea has been oil pollution, which is associated both with oil production and transportation, as well as changes in sea level, leading to secondary pollution, river runoff and even seismic activity, which provokes natural oil spills from the bottom of the sea. Abnormal bloom of waters every year becomes more and more long and covers more and more areas, and also occurs in areas where it was not previously observed. However, the current state of the sea, and the trends of its evolution has not been studied enough, which determines the relevance of the solution of the main task of the ongoing Russian Science Foundation Project “Assessing ecological variability of the Caspian Sea in the current century using satellite remote sensing data”. Implementation of the proposed project will assess the relative contribution of each of the sources of pollution of the Caspian Sea, which varies in different periods depending on climatic factors, on the intensity of various hydrodynamic and hydrometeorological processes, on seismic activity and human economic activity. The goal of the project is to assess the changes in the ecological state of the Caspian Sea since the beginning of the current century under the impact of natural and anthropogenic factors. This calls for a detailed analysis of large banks of satellite data acquired over the Caspian Sea from 1999 to 2022 jointly with multi-year hydrometeorological and in situ data. The goal is achievable due to powerful capabilities of the “See the Sea” (STS) information portal developed by the Space Research Institute of the Russian Academy of Sciences (IKI RAS) as part of IKI - Monitoring Center for Collective Use. STS offers oceanographers new and unique tools to work with remote sensing data, enabling comprehensive analysis of data different in physical nature, spatial resolution and time of acquisition.

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Hinojosa, Hector R. « The Importance of Assessing the Geological Site Effects of Ancient Earthquakes from the Archaeoseismological Point of View ». Eng 4, n^o 1 (22 février 2023) : 719–37. http://dx.doi.org/10.3390/eng4010043.

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Earthquakes have and continue to, occur worldwide, though some places are affected more than others by earthquake-induced ground shaking and the same earthquake can cause more damage in one area than in nearby locations due to site-specific geological site conditions, also known as local site effects. Depending on the chronology of the earthquakes, various disciplines of seismology include instrumental and historical seismology, archaeoseismology, palaeoseismology and neotectonics, each focusing on using specific sources of information to evaluate recent or ancient earthquakes. Past earthquakes are investigated to expand the pre-instrumental and instrumental earthquake catalog and better evaluate a region’s seismic hazard. Archaeoseismology offers a way to achieve these goals because it links how ancient civilizations and their environment might have interacted and responded to past earthquake-induced ground motion and soil amplification. Hence, archaeoseismology explores pre-instrumental (past) earthquakes that might have affected sites of human occupation and their nearby settings, which have left their co-seismic marks in ancient manufactured constructions exhumed by archaeological excavations. However, archaeoseismological observations are often made on a limited epicentral area, poorly constrained dated earthquakes and occasionally on unclear evidence of earthquake damage. Archaeological excavations or field investigations often underestimate the critical role that an archaeological site’s ancient geological site conditions might have played in causing co-seismic structural damage to ancient anthropogenic structures. Nevertheless, the archaeological community might document and inaccurately diagnose structural damage by ancient earthquake shaking to structures and even estimate the size of past earthquakes giving little or no consideration to the role of geological site effects in addressing the causative earthquake. This mixture of factors frequently leads to imprecise estimates of the size of ancient earthquakes and unlikely earthquake environmental impacts, leaving unexplained the location and the moment magnitude of the causative earthquake. Hence, it is essential not to rely solely on earthquake intensities based on archaeologically documented co-seismic damage without assessing the nature of the observed structural damage and the contribution of the geological site effects. This paper explains the geological site effects concept to archaeologists unfamiliar with the notion. It clarifies its role in assessing ground shaking, soil amplification and earthquake intensity by past earthquakes and how and why the geological site effects can be estimated when a site is thought to have been struck by an earthquake. Hence, the geological site effects must be considered when archaeological excavations describe and interpret destruction layers. Conversely, engineers and seismologists dealing with seismic hazard risk assessment must pay close attention to archaeological investigations assessing earthquake intensities and locations based on field evidence of damage to structures attributed to past earthquakes, because the geological site effects might have been factored in inaccurately or not at all.

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Artemeva, Olga, Aleksandr Bakulev, Natalya Pozdnyakova et Sergey Tyurin. « Dynamic mapping of disturbed lands using remote sensing data ». InterCarto. InterGIS 28, n^o 2 (2022) : 785–99. http://dx.doi.org/10.35595/2414-9179-2022-2-28-785-799.

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Due to the increase in the areas of disturbed lands, the relevance of developing methods and methods for obtaining and analyzing spatial data in order to make decisions on rational nature management is increasing every year. Monitoring of natural and anthropogenic systems is largely related to the collection, analysis and visualization of dynamic processes, so the technologies for compiling of dynamic maps are at the peak of relevance. A number of factors necessitate the using of dynamic geoimages. Firstly, these images are an inseparable combination of spatial-temporal links on the certain areas. Secondly, it is the possibility of a full-fledged analysis of spatial changes taking into account time. Thirdly, it is the forecasting of natural and socio-economic factors and phenomena. In addition, dynamic mapping opens up opportunities for multimedia data visualization, which increases the observer’s perception of geoimages by several times with the focus on specific objects. Remote sensing data is one of the main sources for compiling and updating thematic dynamic maps. This article demonstrates the development of the method for creating working layers used in geographic information systems (GIS) for compiling dynamic maps using remote sensing data. The authors note a distinctive feature of the methodology: it is aimed at a wide range of users who do not fully have the skills and abilities to work with remote sensing data. These are managers of any level, whose direct work is not related to the compiling of geo-images, but whose competence is to make managerial decisions. Another advantage of the described methods is its implementation in an open source GIS (QGIS), as well as its application not only for single images, but also for a mosaic image. The article presents a description of the entire path from image processing to the creation of visual images. Disturbed lands of the Zabaykalsky Krai of the Russian Federation were chosen as a special example of working polygons. These territories have a large number of environmental problems, causing an increase in the areas of disturbed lands: open pits, an increase in the number of mining and processing factories, degradation of agricultural and forest lands due to anthropogenic activities and erosion processes, active seismic processes, mudflows and avalanche hazard.

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Hofman, Robert J. « Marine Sound Pollution : Does It Merit Concern ? » Marine Technology Society Journal 37, n^o 4 (1 décembre 2003) : 66–77. http://dx.doi.org/10.4031/002533203787537014.

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The possible effects on marine mammals and other marine organisms of sound from human (anthropogenic) sources have become subjects of increasing concern and controversy. In the late 1970s and 1980s, the sources of principal concern were seismic profiling, drilling, and related activities associated with offshore oil and gas development. In the last decade, much of the focus has shifted to activities conducted or supported by the U.S. Navy, most notably the Acoustic Thermometry of Ocean Climate Program, ship-shock tests, development and proposed use of low frequency active sonar to detect new classes of quiet submarines, and the stranding of beaked whales and other cetaceans in the Bahamas in March 2000 coincident with antisubmarine exercises involving use of mid-frequency tactical sonars. There has been substantial controversy concerning the possible impacts of these activities, and a number of law suits seeking to stop or restrict them. The Navy believes that the concerns are unwarranted and that the law suits have impeded its ability to meet its national defense responsibilities. Congress agreed and in the National Defense Authorization Act for Fiscal Year 2004 (Public Law 108-87) made two substantial changes to the Marine Mammal Protection Act (MMPA): (1) it authorized the Secretary of Defense to exempt military readiness activities from the provisions of the MMPA governing the incidental taking of marine mammals; and (2) it added to the Act separate definitions of harassment to apply to such activities. These and other proposed changes to the MMPA could undermine the unique, precautionary or risk-averse philosophy of the Act. An alternative, two-step approach, advocated in this paper, would be to (a) revise the definition of harassment to clearly differentiate types and levels of behavioral disturbance likely to have, and not to have, biologically significant effects; and (b) add a general authorization for all incidental taking expected to have biologically insignificant effects, similar to the general authorization for marine mammal research expected to have biologically insignificant effects added to the MMPA in 1994.

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Bugai, Dmytro, Sergiy Scherbyna, Tetiana Kril, Iryna Cherevko et Stella Shekhunova. « REVIEW OF MODERN TECHNOLOGIES FOR "STRUCTURAL HEALTH MONITORING" (SHM) OF HISTORICAL BUILDINGS IN COMPLEX ENGINEERING AND GEOLOGICAL CONDITIONS : SENSORS, DATA ANALYSIS METHODS AND PROSPECTS FOR APPLICATION IN UKRAINE ». Collection of Scientific Works of the Institute of Geological Sciences of the NAS of Ukraine 16, n^o 2 (22 décembre 2023) : 76–86. https://doi.org/10.30836/igs.2522-9753.2023.293237.

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A brief overview of modern technologies of “Structural Health Monitoring” (SHM) of building structures is presented. The main attention is paid to the analysis of the world experience and features of the application of SHM to historical buildings, which are situated in difficult geothechnical conditions and are exposed to the influence of dangerous geological processes. The goals and principles of the methodology are outlined. An overview of the main types of instrumental sensors (in particular, accelerometers, acoustic emission sensors, GPS sensors, and sensors of environmental conditions) is presented. The methods of mathematical analysis and interpretation of the received data streams are discussed. The article demonstrates the significance of employing contemporary SHM technologies for architectural monuments within the National Reserve “Kyiv-Pechersk Lavra”. These structures are situated in challenging engineering and geological contexts, and are susceptible to hazardous effects from both natural (landslide processes, meteorological factors) and anthropogenic (waterlogging of foundation soils due to leaks from engineering networks, vibration loads from transport, blast waves due to military operations, etc.) sources. The pilot experience of applying the SHM methodology to the objects of the Kyiv-Pechersk Lavra National Reserve is discussed. The work on testing of sensors (accelerometers, bicycle meters, laser inclinometer) for recording vibrometric, seismic and deformation effects on the objects of the reserve is described. A method of automatic extraction of a useful signal of the ‘microcrack’ type for an accelerometer sensor is presented. The results of the test operation of a 3D laser inclinometer for studying the directions of sliding and deformation of historical buildings and structures, in particular, due to landslides and soil subsidence, etc. are presented.

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Fahmy, Abdelrhman, Eduardo Molina-Piernas et Salvador Domínguez-Bella. « Conservation Assessment of the Stone Blocks in the Northeast Corner of the Karnak Temples in Luxor, Egypt ». Minerals 14, n^o 9 (30 août 2024) : 890. http://dx.doi.org/10.3390/min14090890.

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The Karnak Temples complex, a monumental site dating back to approximately 1970 BC, faces significant preservation challenges due to a confluence of mechanical, environmental, and anthropogenic factors impacting its stone blocks. This study provides a comprehensive evaluation of the deterioration affecting the northeast corner of the complex, revealing that the primary forms of damage include split cracking and fracturing. Seismic activities have induced out-of-plane displacements, fractures, and chipping, while flooding has worsened structural instability through uplift and prolonged water exposure. Soil liquefaction and fluctuating groundwater levels have exacerbated the misalignment and embedding of stone blocks. Thermal stress and wind erosion have caused microstructural decay and surface degradation and contaminated water sources have led to salt weathering and chemical alterations. Multi-temporal satellite imagery has revealed the influence of vegetation, particularly invasive plant species, on physical and biochemical damage to the stone. This study utilized in situ assessments to document damage patterns and employed satellite imagery to assess environmental impacts, providing a multi-proxy approach to understanding the current state of the stone blocks. This analysis highlights the urgent need for a multi-faceted conservation strategy. Recommendations include constructing elevated platforms from durable materials to reduce soil and water contact, implementing non-invasive cleaning and consolidation techniques, and developing effective water management and contamination prevention measures. Restoration should focus on repairing severely affected blocks with historically accurate materials and establishing an open museum setting will enhance public engagement. Long-term preservation will benefit from regular monitoring using 3D scanning and a preventive conservation schedule. Future research should explore non-destructive testing and interdisciplinary collaboration to refine conservation strategies and ensure the sustained protection of this invaluable historical heritage.

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Bishop, Jordan W., David Fee et Curt A. L. Szuberla. « Improved infrasound array processing with robust estimators ». Geophysical Journal International 221, n^o 3 (9 mars 2020) : 2058–74. http://dx.doi.org/10.1093/gji/ggaa110.

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SUMMARY Infrasound array data are commonly used to detect and characterize infrasonic signals from a variety of natural and anthropogenic sources. Here we examine the effectiveness of robust regression estimators (L1-norm regression, M-estimators and least trimmed squares) for infrasound array processing, and compare them against standard array processing algorithms (least-squares estimation, frequency–wavenumber analysis and progressive multi-channel correlation) using a combination of real and synthetic data. Of particular interest is how each algorithm performs when one of the array elements produces data outliers. Synthetic tests on elements containing a clock error, constant values or only pink noise are performed, and we analyse the relative ability of the estimators to recover plane wave parameters. The L1-norm regression, M-estimate, frequency–wavenumber analysis and least trimmed squares estimates provided superior results than conventional least-squares estimation. Evaluation of least trimmed squares weights consistently identified the element with the simulated error, providing additional information on array performance. Least trimmed squares processing consistently identified an element with reversed polarity for Alaska Volcano Observatory array ADKI. International Monitoring System stations IS57 and IS55 were likewise processed. Data from an element of IS57, which had lower cross-correlation values than the remaining elements, were consistently identified as having outliers in array processing. An element with a timing error was identified in the analysis of IS55 data. These results suggest robust regression methods, in particular least trimmed squares, improve upon standard methods and should be used more widely, as they can provide robust array processing results and insight into array performance. Further, robust regression methods are not limited to infrasound array processing applications, and it is likely that they would also be effective for seismic array data.

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Atanasova, Mila, Hristo Nikolov, Ivan Georgiev, Keranka Vassileva, Nikolay Dimitrov et Anton Ivanov. « Creating a thematic geodatabase for monitoring the landslide processes of the landslide circus “Dalgia yar” ». IOP Conference Series : Earth and Environmental Science 906, n^o 1 (1 novembre 2021) : 012035. http://dx.doi.org/10.1088/1755-1315/906/1/012035.

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Abstract Impact on the process of landslide origin and activation is result of many factors both endogenous and exogenous. The purpose of this study is to provide possibility for analysis and assessment of the geo-processes in the “Dalgia yar” landslide located at Northern Black Sea coast of Bulgaria in order to prevent risks and disasters of natural and anthropogenic origin. An important stage was to seamlessly include data from different sources such as geodetic measurements, satellite SAR (Synthetic-aperture radar) data as well as geological and geophysical data. The established geodatabase structures the collected information on dangerous geo-processes in the mentioned area and introduces them into the GIS (Geographic information system) environment. Its purpose is to facilitate the analysis of the available geological data for this landslide and to integrate them with results of measurements from regular monitoring. Interferometric images (IFIs), data from permanent GNSS (Global Navigation Satellite Systems) stations and from local geodynamic GNSS network, geological, seismic and geophysical data, updated geological maps and maps of the risk of landslide processes are included in the database. The IFIs have been produced using well established procedure for processing large number of Sentinel-1 SAR data of the purposely created local archive. Other key element used to improve the final results of SAR data processing and important part of the geodatabase is the precise Digital Elevation Model (DEM), which is much better in terms of horizontal and vertical resolutions than the open accessed ones (SRTM). The coordinates and velocities of the GNSS points are obtained from adjustment and analysis of two epoch measurements of the geodynamic control network of landslides “Dalgia yar”. Since the area has complex geological structure, small scale maps reflecting the geological and geophysical hazards are integral part of the geodatabase. Having all this information the analysis concerning the ongoing geodynamical processes in the study area is significantly improved and more reliable information is produced for better regional planning by the local authorities and residents.

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Zhao, Min, Yuping Qi, Feng Long, Liyuan Peng, Chang He, Di Wang et Xiyang Ran. « Characterization of the Solution of the Seismic Source Mechanism in Southeastern Sichuan ». Applied Sciences 15, n^o 7 (1 avril 2025) : 3881. https://doi.org/10.3390/app15073881.

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Southeastern Sichuan has witnessed intensified seismic swarm activity since 2016, including events exceeding historical peak ground accelerations. This study integrates moment tensor solutions, stress field inversion, and Mohr–Coulomb analysis to investigate the interplay between tectonic processes and shale gas extraction in driving seismicity. Full-waveform moment tensor inversions of 118 earthquakes (M ≥ 3.5) reveal predominant double-couple mechanisms (62% with DC > 70%), with minor non-double-couple components linked to fluid-induced volume contraction. Stress field inversions demonstrate spatial heterogeneity: Region A (south) exhibits a counterclockwise-rotated maximum horizontal stress direction compared to Region B (north), which aligns with the regional NW-SE tectonic compression. Mohr’s circle analysis highlights distinct failure regimes—40% of the events in Region A fall below the failure threshold (pore-pressure-influenced), while 60% in Region B exceed it (stress-dominated). These findings underscore the combined roles of tectonic inheritance (NE-SW basement faults) and anthropogenic perturbations (fluid injection) in modulating seismic hazards.

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Walter, Fabian, Arnaud Burtin, Brian W. McArdell, Niels Hovius, Bianca Weder et Jens M. Turowski. « Testing seismic amplitude source location for fast debris-flow detection at Illgraben, Switzerland ». Natural Hazards and Earth System Sciences 17, n^o 6 (22 juin 2017) : 939–55. http://dx.doi.org/10.5194/nhess-17-939-2017.

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Abstract. Heavy precipitation can mobilize tens to hundreds of thousands of cubic meters of sediment in steep Alpine torrents in a short time. The resulting debris flows (mixtures of water, sediment and boulders) move downstream with velocities of several meters per second and have a high destruction potential. Warning protocols for affected communities rely on raising awareness about the debris-flow threat, precipitation monitoring and rapid detection methods. The latter, in particular, is a challenge because debris-flow-prone torrents have their catchments in steep and inaccessible terrain, where instrumentation is difficult to install and maintain. Here we test amplitude source location (ASL) as a processing scheme for seismic network data for early warning purposes. We use debris-flow and noise seismograms from the Illgraben catchment, Switzerland, a torrent system which produces several debris-flow events per year. Automatic in situ detection is currently based on geophones mounted on concrete check dams and radar stage sensors suspended above the channel. The ASL approach has the advantage that it uses seismometers, which can be installed at more accessible locations where a stable connection to mobile phone networks is available for data communication. Our ASL processing uses time-averaged ground vibration amplitudes to estimate the location of the debris-flow front. Applied to continuous data streams, inversion of the seismic amplitude decay throughout the network is robust and efficient, requires no manual identification of seismic phase arrivals and eliminates the need for a local seismic velocity model. We apply the ASL technique to a small debris-flow event on 19 July 2011, which was captured with a temporary seismic monitoring network. The processing rapidly detects the debris-flow event half an hour before arrival at the outlet of the torrent and several minutes before detection by the in situ alarm system. An analysis of continuous seismic records furthermore indicates that detectability of Illgraben debris flows of this size is unaffected by changing environmental and anthropogenic seismic noise and that false detections can be greatly reduced with simple processing steps.

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Burdzieva, Olga, Dmitry Melkov, Mairbek Revazov et Alan Kortiev. « Activation of landslide processes caused by urbanization of mountainous areas ». Sustainable Development of Mountain Territories 16, n^o 4 (30 décembre 2024) : 1646–58. https://doi.org/10.21177/1998-4502-2024-16-4-1646-1658.

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Introduction. Dangerous exogenous processes of various nature including landslides, are significantly developed on the territory of the North Caucasus. A large number of various dangerous emergency situations are associated with them. The active development of domestic tourism in Russia in recent years contributes to the active development of previously unused high-mountainous territories of the North Caucasus, simultaneously increasing the geoecological load, which determines the relevance of its assessments. The purpose of the work is to identify and assess the factors that form the load on the natural system, subject to regular and long-term anthropogenic impact. Materials and methods. The study uses methods of expert assessments of impacts of various natures, which are based on modern concepts of geodynamic processes in rocks. The use of expert assessments made it possible to introduce quantitative characteristics of impacts caused by lithological, geomorphological, endogenous, exogenous geological and natural-climatic factors. Results. It has been established that endogenous activity is a significant factor in the activation of exogenous processes, which are characterized by stable association with tectonic faults and nodes of different-rank fault structures, focal zones of seismic and volcanoplutonic activity. Discussion. The assessment of the level of geoecological loads assumes the necessity of identifying the factors that form them. It becomes possible to forecast the impact of natural and man-made loads and develop measures to mitigate the consequences of the development of dangerous natural processes and the manifestation of dangerous exogenous processes: landslides, mudflows, collapses during practical construction. Conclusion. 1. The stress-strain state of a rock massif under natural conditions is the most important characteristic of the manifestations of geodynamic effects. Potential sources of dangerous geological processes are in a state of varying degrees of equilibrium, the exit from which is possible when a certain situation arises. 2. Endogenous activity is the causal factor in the activation of exogenous processes, including landslides. An important factor in the development and subsequent accumulation of quaternary deposits are endogenous processes. The diversity of the lithological composition of rocks and the activity of geological processes determine the diversity of genetic types of quaternary deposits. Resume. Using expert assessments, the contribution of each factor to the formation of vulnerability and risk was assessed. Zoning of the geoecological load was performed using the example of a mountain range between the valleys of the Ardon and Fiagdon rivers and adjacent territories Suggestions for practical applications and future research directions. It becomes possible to forecast the level of impact of natural and man-made loads and develop measures to mitigate the severity of the consequences of the development of hazardous natural processes and the manifestation of hazardous exogenous processes: landslides, mudflows, rockfalls during practical construction.

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Biehichev, S. V., et G. S. Ishutina. « UPDATE OF GEOMONITORING TECHNOLOGIES AS A FACTOR OF ENSURING THE SAFE OPERATION OF BUILDINGS AND STRUCTURES ». Ukrainian Journal of Civil Engineering and Architecture, n^o 4 (016) (8 octobre 2023) : 17–26. http://dx.doi.org/10.30838/j.bpsacea.2312.290823.17.966.

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Obtaining reliable data based on the results of geomonitoring allows timely measures to stabilize deformations of buildings and structures. Implementation of the scientific justification for the development of methodological recommendations is required to increase the stability of structures and take the necessary measures to protect buildings in case of detection of unacceptable deformations. Among the causes of deformations, it is possible to single out the imperfection of the structures of the building, the influence of natural conditions (changes in temperature, groundwater level, wind action, seismic events, geological conditions) and anthropogenic human influence (mechanical loads). The purpose of the work is to study research of existing methods of geomonitoring for deformations of buildings and structures in dense urban development. Comparative analysis of geomonitoring methods and the formation of proposals for their rational and mandatory use. Methodology. Analysis of regulatory and literary sources on geodetic monitoring of buildings and structures. Analysis of foreign experience of observation of towers using modern 3D laser scanning technologies. Comparative analysis of accuracy and economic characteristics of methods of monitoring buildings and structures. Scientific novelty. It is recommended during the design process to include geodetic marks for the monitoring network in the projects of buildings and structures, so as not to spoil their architectural appearance at the stage of operation, if necessary, to carry out geodetic monitoring. By using modern geodetic monitoring methods with innovative modern technologies, it is possible to obtain a three-dimensional picture of the deformation of buildings and structures. These actions are performed in order to take timely measures to combat them and develop protective measures to prevent further destruction of buildings. Practical value. Nowadays, with the development of technologies and the appearance of modern equipment, the combined method of geomonitoring has become widely used. This method involves a combination of tacheometric surveying with terrestrial laser scanning and digital stereo photography. This allows you to get a three-dimensional 3D picture of the deformations of the entire building (both foundations and walls). An analogue of this method is the use of traditional ground methods − leveling and plan-altitude surveying, and the prototype − ground stereo photography. However, there are often cases when geodetic observations of deformations of foundations and foundations of structures are neglected in order to save the construction budget. Results. Types and causes of deformations of engineering structures are analyzed. Modern technologies of geodetic monitoring are considered, their advantages and disadvantages are revealed. Attention is drawn to compliance with the requirements of regulatory documents and the rational choice of an economically feasible technology for conducting geodetic monitoring using reliable geodetic points. In large cities with different building densities and the presence of various architectural ensembles, during the development of construction works, it is necessary to have a reliable geodetic basis. A reliable geodetic network can be formed by regular monitoring of the existing urban geodetic network.

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Loginov, D. S. « Implementing a web service for cartographic monitoring of the geological exploration field stage using open-source software ». Geodesy and Cartography 991, n^o 1 (20 février 2023) : 29–41. http://dx.doi.org/10.22389/0016-7126-2023-991-1-29-41.

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The author presents the results of a web service development aimed at implementing a conceptual model of field geophysical surveys mapping monitoring. The issues of adapting the open source software DBMS PostgreSQL and JavaScript library Leaflet for centralized data gathering, systematization, updating and cartographic visualization of the geological exploration’s field phase progress are considered. The web service was tested during the seismic acquisition at the license areas in the Russian Federation and the Republic of India. It was used as the main tool for spatial analysis of the field crews’ productivity and considering natural and anthropogenic objects that prevent the timely execution of planned volumes of topographic and geodetic and seismic surveys, as well as a means of communication between specialists and administrative decision making. The results of the approbation showed an increase in the efficiency of geological exploration works’ field phase cartographic support. The experience of using open source software, a systematic approach to forming the server space and storing information in the database presented in the article enables developing web-mapping of exploration work carried out simultaneously in several territories through different methods of geophysical exploration.

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ГРЕБЕНЩИКОВА, В. И., М. И. КУЗЬМИН et В. М. ДЕМЬЯНОВИЧ. « DIFFERENT DYNAMICS OF THE CHEMICAL COMPOSITION OF WATER IN THE BAIKAL ECOSYSTEM (BAIKAL, ITS TRIBUTARIES, AND THE SOURCE OF THE ANGARA RIVER) ». Геология и геофизика 65, n^o 3 (3 juin 2024) : 386–400. http://dx.doi.org/10.15372/gig2023162.

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Установлена разнонаправленная динамика изменения химического состава воды единственного стока о. Байкал — р. Ангара. Выявлен циклично-волновой характер изменения межгодового химического состава байкальской воды, что свидетельствует о наличии эффекта долговременной памяти в химических временных рядах элементов. Проявлены положительные и отрицательные температурные и химические тренды состояния воды истока Ангары, обусловленные изменением климата, влиянием приуроченности Байкала к рифтовой зоне, составом вмещающих пород. Показано, что текущие значения контролируемых элементов в воде истока Ангары зависят и от их прошлых значений, но могут резко изменяться при катастрофических нарушениях окружающей среды за счет природных и антропогенных катаклизмов (пожары, засуха, наводнения, землетрясения и др.). Прослежена связь между повышенными значениями урана в воде с сейсмическим процессом в районе озера Байкал. Полученные данные основаны на многолетних (1950—2021 гг.) мониторинговых исследованиях химического состава воды сопряженных компонентов Байкальской экосистемы (вода Байкала, притоки, исток Ангары). Multidirectional dynamics of changes in the chemical composition of the water of the only runoff of Lake Baikal, the Angara River, has been established. The cyclic-wave change in the interannual chemical composition of the Baikal water has been revealed, which indicates a long-term memory effect in the chemical time series of elements. Positive and negative temperature and chemical trends in the state of the water in the source of the Angara are observed, which are due to climate changes, the confinement of Baikal to the rift zone, and the composition of the enclosing rocks. It is shown that the current concentrations of monitored elements in the Angara source water depend also on their past concentrations but can change dramatically in the case of catastrophic environmental disturbances caused by natural and anthropogenic disasters (fires, drought, floods, earthquakes, etc.). The relationship between the elevated concentrations of uranium in the water and the seismic process in the Baikal area has been traced. The data obtained are based on the long-term (1950–2021) monitoring of the chemical composition of water in the Baikal ecosystem (Baikal, its tributaries, and Angara source).

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