Academic literature on the topic 'Source depth and mechanism inversion'
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Journal articles on the topic "Source depth and mechanism inversion"
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Marson-Pidgeon, K. "Source Depth and Mechanism Inversion at Teleseismic Distances Using a Neighborhood Algorithm." Bulletin of the Seismological Society of America 90, no. 6 (December 1, 2000): 1369–83. http://dx.doi.org/10.1785/0120000020.
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Allamehzadeh, M., M. Dezvareh, A. M. Farahbod, D. Hatzfeld, M. Mokhtari, A. S. Moradi, M. Mostafazadeh, A. Paul, and M. Tatar. "Seismological Aspects of the 2003 Bam, Iran, Earthquake and Its Aftershock Analysis." Earthquake Spectra 21, no. 1_suppl (December 2005): 101–12. http://dx.doi.org/10.1193/1.2098167.
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The source mechanism derived from the inversion of long-period body waves revealed that the earthquake occurred on a north-south trending strike-slip fault with a thrust component. According to the source model estimated in this study, the 2003 Bam, Iran, earthquake was a multiple event formed by two subevents. The rupture following subevent one started at a depth of about 8 km. However, the depth of subevent two is about 10 km. The total seismic moment estimated from inversion processes is 8.34×1018Nm. The pulse duration of subevent one and subevent two was determined from source time function as 1.7 s and 0.8 s, respectively. Corner frequency and source radius have been calculated by using major pulse duration. The corner frequency and source radius are 0.187 Hz and 5.47 km, respectively. The aftershock events distributed along a 30 km north-south striking fault. The focal depths of aftershocks distribution show a nearly vertical alignment of aftershocks located between 6 and 20 km depth. The focal mechanism solutions of aftershocks indicate right-lateral strike-slip faulting on a north-south trending fault, parallel to the previously known Bam fault trace in the east of Bam.
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Beck, Susan L., and Howard J. Patton. "Inversion of regional surface-wave spectra for source parameters of aftershocks from the Loma Prieta earthquake." Bulletin of the Seismological Society of America 81, no. 5 (October 1, 1991): 1726–36. http://dx.doi.org/10.1785/bssa0810051726.
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Abstract Surface waves recorded at regional distances are used to study the source parameters for three of the larger aftershocks of the 18 October 1989, Loma Prieta, California, earthquake. The short-period P-wave first-motion focal mechanisms indicate a complex aftershock sequence with a wide variety of mechanisms. Many of these events are too small for teleseismic body-wave analysis; therefore, the regional surface-waves provide important long-period information on the source parameters. Intermediate-period Rayleigh- and Love-wave spectra are inverted for the seismic moment tensor elements at a fixed depth and repeated for different depths to find the source depth that gives the best fit to the observed spectra. For the aftershock on 19 October at 10:14:35 (md = 4.2), we find a strike-slip focal mechanism with right lateral motion on a NW-trending vertical fault consistent with the mapped trace of the local faults. For the aftershock on 18 October at 10:22:04 (md = 4.4), the surface waves indicate a pure reverse fault with the nodal planes striking WNW. For the aftershock on 19 October at 09:53:50 (md = 4.4), the surface waves indicate a strike-slip focal mechanism with a NW-trending vertical nodal plane consistent with the local strike of the San Andreas fault. Differences between the surface-wave focal mechanisms and the short-period P-wave first-motion mechanisms are observed for the aftershocks analyzed. This discrepancy may reflect the real variations due to differences in the band width of the two observations. However, the differences may also be due to (1) errors in the first-motion mechanism due to incorrect near-source velocity structure and (2) errors in the surface-wave mechanisms due to inadequate propagation path corrections.
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Zhu, Lupei, and Donald V. Helmberger. "Advancement in source estimation techniques using broadband regional seismograms." Bulletin of the Seismological Society of America 86, no. 5 (October 1, 1996): 1634–41. http://dx.doi.org/10.1785/bssa0860051634.
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Abstract One important constraint on source retrieval from regional seismograms comes from the amplitude difference between various phases (such as Pnl/surface wave, SV/SH). Because the misfit errors used in some waveform inversions are normalized by the data and synthetics, the amplitude information in the data has not been fully utilized. In this article, we modify the “cut and paste” source estimation technique (Zhao and Helmberger, 1994) by removing this type of normalization. It is shown that the modified method increases the stability and resolution of inversion. When multiple stations at different distance ranges are used, a distance scaling factor is introduced to compensate for the amplitude decay with distance. By applying the technique to the TERRAscope data, we have determined source mechanisms and depths of 335 southern Californian events with ML ≧ 3.5. The amplitude decays with distance are r1.13 for Pnl, r0.55 for Love waves, and r0.74 for Rayleigh waves. In contrast to generally shallow source depths reported by the southern California short-period network, the depth distribution from waveform inversion shows a strong peak around 12 km with few earthquakes occurring above 5 km and below 20 km.
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Daniarsyad, Gatut, Aprilia Nur Vita, and Shengji Wei. "Focal Mechanism Analysis of the September 25th, 2019 Mw 6.5 Ambon Earthquake and Its Implication for Seismotectonics." IOP Conference Series: Earth and Environmental Science 873, no. 1 (October 1, 2021): 012032. http://dx.doi.org/10.1088/1755-1315/873/1/012032.
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Abstract On September 25th, 2019, an Mw 6.5 earthquake occurred in Ambon, Maluku Province, Indonesia, and caused casualties and infrastructures damages. The epicenter located in a tectonically active region with the potential strike-slip and thrust faulting earthquake sources, yet the responsible fault is still not well understood. Based on focal mechanism solutions from available seismological agencies, i.e. USGS, GFZ, GCMT, and BMKG, the earthquake has a similar strike-slip focal mechanism, although there are discrepancies on detailed source parameters. To provide a better understanding of the earthquake mechanism and seismotectonic, we apply the Cut-and-Paste (CAP) focal mechanism inversion method to broadband seismic waveforms from regional and teleseismic distances. The CAP inversion results on the regional data grouped in different distance ranges show a robust strike-slip solution. We then refine the earthquake focal depth by performing the CAPtele inversion and resulted in a depth of 12 km with similar fault plane solution as the regionals. The ruptured fault plane is resolved by a directivity analysis using azimuthal pattern of the apparent source durations, which indicates an obvious unilateral rupture propagation toward SSE direction. Our result suggests the NNW-SSE orientated fault is the ruptured fault plane, which is also consistent with the near N-S distributed aftershocks. This fault is located in a narrow sea between Seram, Ambon and Haruku island and was not reported yet in previous studies. The Coulomb failure stress (CFS) changes analysis of the mainshock shows that the Ambon earthquake has promoted the off-fault aftershocks which occurred to the west of the ruptured fault.
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Stähler, S. C., and K. Sigloch. "Fully probabilistic seismic source inversion – Part 1: Efficient parameterisation." Solid Earth 5, no. 2 (November 17, 2014): 1055–69. http://dx.doi.org/10.5194/se-5-1055-2014.
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Abstract. Seismic source inversion is a non-linear problem in seismology where not just the earthquake parameters themselves but also estimates of their uncertainties are of great practical importance. Probabilistic source inversion (Bayesian inference) is very adapted to this challenge, provided that the parameter space can be chosen small enough to make Bayesian sampling computationally feasible. We propose a framework for PRobabilistic Inference of Seismic source Mechanisms (PRISM) that parameterises and samples earthquake depth, moment tensor, and source time function efficiently by using information from previous non-Bayesian inversions. The source time function is expressed as a weighted sum of a small number of empirical orthogonal functions, which were derived from a catalogue of >1000 source time functions (STFs) by a principal component analysis. We use a likelihood model based on the cross-correlation misfit between observed and predicted waveforms. The resulting ensemble of solutions provides full uncertainty and covariance information for the source parameters, and permits propagating these source uncertainties into travel time estimates used for seismic tomography. The computational effort is such that routine, global estimation of earthquake mechanisms and source time functions from teleseismic broadband waveforms is feasible.
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Stähler, S. C., and K. Sigloch. "Fully probabilistic seismic source inversion – Part 1: Efficient parameterisation." Solid Earth Discussions 5, no. 2 (July 23, 2013): 1125–62. http://dx.doi.org/10.5194/sed-5-1125-2013.
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Abstract. Seismic source inversion is a non-linear problem in seismology where not just the earthquake parameters themselves, but also estimates of their uncertainties are of great practical importance. Probabilistic source inversion (Bayesian inference) is very adapted to this challenge, provided that the parameter space can be chosen small enough to make Bayesian sampling computationally feasible. We propose a framework for PRobabilistic Inference of Source Mechanisms (PRISM) that parameterises and samples earthquake depth, moment tensor, and source time function efficiently by using information from previous non-Bayesian inversions. The source time function is expressed as a weighted sum of a small number of empirical orthogonal functions, which were derived from a catalogue of >1000 STFs by a principal component analysis. We use a likelihood model based on the cross-correlation misfit between observed and predicted waveforms. The resulting ensemble of solutions provides full uncertainty and covariance information for the source parameters, and permits to propagate these source uncertainties into travel time estimates used for seismic tomography. The computational effort is such that routine, global estimation of earthquake mechanisms and source time functions from teleseismic broadband waveforms is feasible.
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Saetang, Kasemsak. "Focal Mechanisms of Mw 6.3 Aftershocks from Waveform Inversions, Phayao Fault Zone, Northern Thailand." International Journal of Geophysics 2017 (2017): 1–7. http://dx.doi.org/10.1155/2017/9059825.
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The focal mechanisms of Mw 6.3 aftershocks, Chiang Rai Province, Northern Thailand, were determined by using a multistation waveform inversion. Three aftershocks were selected and their waveforms were inverted for moment tensor calculation. Waveform inversions were derived from three broadband stations with three components and epicentral distances less than 250 km after all seismic stations were considered. The deviatoric moment tensor inversion was used for focal mechanism calculations. Band-pass filtering in the range of 0.03–0.15 Hz was selected for reducing low- and high-frequency noise. Source positions were created by using a single-source inversion and a grid-search method computed to optimize the waveform match. The results showed stable moment tensors and fault geometries with the southwest azimuth in the northern part of the Payao Fault Zone (PFZ) with depths shallower than 10 km. Left-lateral strike-slip with a reverse component was detected. The tectonics of the PFZ is constrained by fault-plane solutions of earthquakes. WSW directional strikes are observed in the northern part of the PFZ.
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Zhang, Jiajun, and Thorne Lay. "Duration and depth of faulting of the 22 June 1977 Tonga earthquake." Bulletin of the Seismological Society of America 79, no. 1 (February 1, 1989): 51–66. http://dx.doi.org/10.1785/bssa0790010051.
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Abstract The 22 June 1977 (Mw = 8.2) Tonga earthquake has the longest rupture duration ever reported for a normal fault event. The 150-km depth range spanned by aftershocks of the earthquake is also unusually large. There has been substantial controversy over both the depth and duration of faulting for this great event, obscuring its tectonic significance. We study the source process of the Tonga event using long-period Rayleigh waves recorded by the Global Digital Seismograph Network (GDSN) and International Deployment of Accelerometers (IDA) networks. For a standard assumption of a Haskell source, a total duration of 84 ± 4 sec is obtained using a least-squares inversion method. We introduce the use of the spectral amplitude as a weighting factor in measuring the misfit between the data and a given source finiteness model, which reduces the scatter and improves the resolution of source duration determined from data ranging in period from 150 to 300 sec. Using a more realistic shape for the source-time function in the inversion (drawing upon results from body-wave analysis) reveals a much longer (165-sec process time) component of the source process of the Tonga earthquake. The fundamental mode Rayleigh waves do not resolve any horizontal source directivity. However, the centroid depth of the earthquake is well resolved as 96 km with 90 per cent confidence range (93, 104 km). The estimated error in the depth determination due to the uncertainties in the source finiteness and earth models is only a few kilometers. The results indicate that the rupture of the earthquake excited long-period seismic waves at depths somewhat greater than the 70 to 80 km depth range where the primary body-wave radiation occurred, favoring rupture on the steeply dipping plane of the focal mechanism. The fundamental mode Rayleigh waves with periods longer than 150 sec cannot resolve vertical extent of the faulting; however, additional information from body-wave and free oscillation analyses indicates a vertical fault extent of about 50 km with a frequency-dependent variation in seismic radiation with depth.
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Schwartz, Susan Y. "Source parameters of aftershocks of the 1991 Costa Rica and 1992 Cape Mendocino, California, earthquakes from inversion of local amplitude ratios and broadband waveforms." Bulletin of the Seismological Society of America 85, no. 6 (December 1, 1995): 1560–75. http://dx.doi.org/10.1785/bssa0850061560.
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Abstract Source parameters of aftershocks of the 22 April 1991 (MW = 7.7) Costa Rica and the 25 April 1992 (MW = 7.1) Cape Mendocino, California, earthquakes are determined using a grid search inversion of P, SH, and SV amplitude ratios recorded by sparse local networks of three-component broadband and short-period stations. The inversion procedure consists of computing synthetic seismograms for three fundamental fault orientations for all source-receiver pairs over a range of source depths; calculating the complex envelopes of the observed and synthetic seismograms to determine peak amplitudes of P, SH, and SV waves; combining the fundamental fault amplitudes for all possible values of strike, dip, and rake, at 10° increments; and determining the best fault orientation and depth as the one that yields the smallest misfit between observed and synthetic P/SH, P/SV, and SV/SH amplitude ratios. The ambiguity in the sense of motion on the nodal planes, arising due to the use of amplitude ratios, is resolved by examining P-wave polarities. The sensitivity of source parameters to uncertainties in earthquake location and crustal structure is explored. For events with good station coverage, focal mechanism determinations are stable for a wide range of assumed values of crustal structure, earthquake location, and depth. Source parameters for many of the largest events (M > 3.4) are also determined by inversion of broadband displacement waveforms using a similar grid-search technique. Comparable results were obtained using both broadband waveforms and amplitude ratios. Focal mechanism solutions for 20 aftershocks of the Costa Rica earthquake reveal a complicated faulting geometry, indicating active thrust, normal, and strike-slip faults in the back-arc of Costa Rica. The 1992 Cape Mendocino earthquake occurred at the intersection of the North American, Gorda, and Pacific plates. While the mainshock was associated with underthrusting of the Gorda plate beneath the North American plate, fault plane solutions for 70% of the 38 largest aftershocks indicate that these events result from either motion between the Gorda and Pacific plates or from internal deformation within the Gorda plate.
Dissertations / Theses on the topic "Source depth and mechanism inversion"
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Marson-Pidgeon, Katrina Ann, and katrina marson-pidgeon@anu edu au. "Seismogram synthesis for teleseismic events with application to source and structural studies." The Australian National University. Research School of Earth Sciences, 2001. http://thesis.anu.edu.au./public/adt-ANU20010925.152548.
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The aim of this thesis is to develop procedures for the modelling and inversion of teleseismic P and S waveforms which are as flexible as possible. This flexibility is necessary in order to obtain accurate source depth and mechanism estimates for small to moderate size events, such as those that are relevant in the context of monitoring the Comprehensive Nuclear-Test-Ban Treaty (CTBT). ¶
The main challenge for extending source depth and mechanism inversion methods to smaller events is to ensure that sufficiently accurate synthetic seismograms are available for comparison with observed records. An accurate phase-adaptive reflectivity method has therefore been developed, against which the performance of less computationally intensive approximations can be judged. The standard reflectivity method has been modified to allow for different crustal and upper mantle structures at the source and receiver, and the full effects of reverberations and conversions in these structures can be allowed for. Core reflections and refractions can also be included; these phases can become important at certain distance ranges. A slowness bundle approach has been developed, where a restricted slowness integration about the geometric slowness for the direct wave is undertaken at each frequency, allowing accurate results to be obtained whilst avoiding the expense of a full reflectivity technique. ¶ Inversion using the neighbourhood algorithm (NA) is performed for source depth, mechanism and time function, by modelling direct P and S and their surface reflections (pP, sP and pS, sS) at teleseismic distances. Both SV and SH data are exploited in the inversion, in addition to P data, in order to obtain improved constraints on the source mechanism, including any isotropic component. Good results are obtained using a simple generalised ray scheme, however, the use of a flexible derivative-free inversion method means that more accurate synthetics are able to be used in the inversion where appropriate. The NA makes use of only the rank of the data misfits, so that it is possible to employ any suitable misfit criterion. In the few cases where control on the source mechanism is limited, good depth resolution is still usually obtained. ¶The structures near the source and receiver play an important role in shaping the detail of the teleseismic waveforms. Although reasonable results can be achieved with simple synthetics and a standard velocity model, significant improvement can be made by modifying the representation of structure near the source and receiver. In the case of sub-oceanic events it is important to allow for the effects of water reverberations. The crustal structure near the receiver can also have quite a large influence on the waveforms through reverberations and conversions. This is exploited in receiver function inversion, which is again accomplished using the NA approach.
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Beldjoudi, Hamoud. "Modélisation de la source des séismes par inversion des données sismologiques et géodésiques : application aux séismes du Nord de l’Algérie." Thesis, Université Côte d'Azur (ComUE), 2017. http://www.theses.fr/2017AZUR4053/document.
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La caractérisation de la source d’un séisme se fait à partir de l’analyse des mesures des déplacements transitoires et statiques du sol, et dépend de la quantité et de la qualité de ces mesures. Nous avons travaillé sur la détermination des mécanismes au foyer des séismes modérés de Tadjena (Mw 5.0, 2006), Béni-Ilmane (Mw 5.5, 2010), Hammam Melouane (Mw 5.0, 2013), Bordj-Ménaïel (Mw 4.1, 2014), Alger (Mw 5.7, 2014) et M’ziraa (Mw 5.1, 2016). Pour cela, nous avons inversés les formes d’ondes en champ proche et régional des stations large bandes et accélérométriques du réseau sismologique algérien (ADSN). Nous avons déterminé la distribution spatio-temporelle du glissement cosismique du séisme de Boumerdes-Zemmouri (Mw 6.8, 2003) en inversant conjointement l’ensemble des données disponibles, sismologiques (télésismiques, accélérometriques) et géodésiques (GPS, InSAR, soulèvement côtier). Nous avons travaillé sur la relation qui peut exister entre le séisme de Boumerdes-Zemmouri et les séismes de Hammam Melouane, Bordj Ménaïel et Alger (Mw 5.7, 2014) en termes de transfert de contrainte (CFF). Nous avons calculé le champ de contrainte dans différentes régions de l’Algérie par inversion des mécanismes aux foyers disponibles dans chaque régionStudies of the earthquake source are based on observations of seismic and static ground motions, which depend on the quality and the density of measurements. In this thesis, we present studies of the determination of the focal mechanism of the Tadjena (Mw 5.0, 2006), Béni-Ilmane (Mw 5.5, 2010), Hammam Melouane (Mw 5.0, 2013), Bordj-Ménaïel (Mw 4.1, 2014), Alger (Mw 5.7, 2014) and M’ziraa (Mw 5.1, 2016) earthquakes, by modeling waveforms in the near and regional field with broadband and strong motion stations of the Algerian Digital Seismic Netwok (ADSN). In addition, we determined the coseismic slip distribution of the Boumerdes-Zemmouri earthquake (Mw 6.8, 2003) by inverting a most comprehensive set of data (teleseismic, strong motion, GPS, InSAR, coastal uplift). We calculated the Coulomb Failure Function between the Boumerdes-Zemmouri earthquake (source fault) and the Hammam Melouane, Bordj Ménaïel and Algiers (Mw 5.7, 2014) events (receiver faults). We computed the stress tensor in different regions of Algeria obtained from the inversion of the available focal mechanisms
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Balestra, Julien. "Caractérisation de la source des séismes par inversion des données sismologiques et géodésiques : mécanismes au foyer, optimisation des modèles de vitesse, distribution du glissement cosismique." Thesis, Université Côte d'Azur (ComUE), 2017. http://www.theses.fr/2017AZUR4020/document.
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La caractérisation de la source d’un séisme se fait à partir de l’analyse des mesures des déplacements transitoires et statiques du sol, et dépend de la quantité et de la qualité de ces mesures. Nous avons travaillé sur la détermination des mécanismes au foyer des répliques du séisme de Saintes (MW 6.4, 2004), et sur la détermination de la distribution spatio-temporelle du glissement cosismique des séismes de L’Aquila (Mw 6.3, 2009), et de Miyagi-Oki (Mw 7.2, 2005) et de Sanriku-Oki (Mw 7.3, 2011). Ces travaux se sont basés sur des méthodes d’inversions, et différents jeux de données (accélérométriques, large-bandes, GPS et InSAR) accessibles ou non selon le séisme considéré. La seule diversité des mesures n’est pas suffisante pour décrire la rupture. La modélisation des données se confronte à des difficultés, comme par exemple la pertinence des modèles de vitesses sismiques pour la modélisation des données accélérométriques. Une autre problématique récurrente est la non-unicité de la meilleure solution déterminée par les méthodes d’inversions pour décrire les données. Pour répondre à ces deux problématiques, nous avons d‘une part développé une procédure d’exploration de modèles de vitesse pour déterminer les valeurs optimales capables de décrire au mieux les données accélérométriques du séisme de L’Aquila. D’autre part, nous avons développé une procédure de construction d’un modèle de source moyen que nous avons appliqué pour la détermination du glissement cosismique des séismes de L’Aquila, de Miyagi-Oki, et de Sanriku-Oki. L’ensemble de ces travaux et les réponses aux problèmes soulevés sont présentés dans ce travail de thèseStudies of the earthquake source are based on observations of seismic ground motions. They also depend on the quality and the density of measurements. In this present work we will present studies of the determination of focal mechanism of main aftershocks of the Les Saintes (MW 6.4, 2004) earthquake, and the determination of the coseismic slip of the L’Aquila (MW 6.3, 2009), the Miyagi-Oki (MW 7.2, 2005), ant the Sanriku-Oki (MW 7.3, 2011) earthquakes. These studies were based on two inversion methods. Different kinds of data were available (strong motion, broadband teleseismic, GPS and InSAR) depending on the earthquake studied. But the multiplicity of data is not sufficient to well describe rupture process. There are others difficulties as the data modeling of strong motion. Seismic velocity models are used to describe the characteristics of layers crossed by seismic waves. The quality of the modeling is depending on the pertinence of these seismic velocity models. The description of the rupture process is also depending on the non-uniqueness of the best solution given by global inversion methods. We propose two procedures in order to take into account these two classic issues. First, we developed a velocity model exploration procedure to obtain optimized 1D velocity models in order to improve the strong motion modeling of the L’Aquila earthquake. Then we developed a procedure to build an average rupture model from the combined results of several joint inversions, which was applied to the L’Aquila, the Miyagi-Oki, and the Sanriku-Oki earthquake. This thesis presents all these works and answers to the raised issues
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Marson-Pidgeon, Katrina Ann. "Seismogram synthesis for teleseismic events with application to source and structural studies." Phd thesis, 2001. http://hdl.handle.net/1885/47797.
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The aim of this thesis is to develop procedures for the modelling and inversion of teleseismic P and S waveforms which are as flexible as possible. This flexibility is necessary in order to obtain accurate source depth and mechanism estimates for small to moderate size events, such as those that are relevant in the context of monitoring the Comprehensive Nuclear-Test-Ban Treaty (CTBT). ¶ The main challenge for extending source depth and mechanism inversion methods to smaller events is to ensure that sufficiently accurate synthetic seismograms are available for comparison with observed records. An accurate phase-adaptive reflectivity method has therefore been developed, against which the performance of less computationally intensive approximations can be judged. The standard reflectivity method has been modified to allow for different crustal and upper mantle structures at the source and receiver, and the full effects of reverberations and conversions in these structures can be allowed for. Core reflections and refractions can also be included; these phases can become important at certain distance ranges. A slowness bundle approach has been developed, where a restricted slowness integration about the geometric slowness for the direct wave is undertaken at each frequency, allowing accurate results to be obtained whilst avoiding the expense of a full reflectivity technique. ¶ ...
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Lin, Jiun-Ting, and 林駿廷. "Inversion of GPS coseismic displacements for earthquake source mechanism." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/25889279224935715982.
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碩士國立中央大學
地球科學學系
102
Inversion of the earthquake source information by using seismic data becomes effective and performs well in the last decades. Such information, including source location, earthquake magnitude and focal mechanism, are important for earthquake and tsunami early warning studies. When earthquakes occur, a preliminarily calculation for earthquake magnitude is based on the amplitude of short period seismic waves in the near-field. However, for larger earthquakes, the energy need more time to release, which constrain the amplitude of high-frequency energy to a constant. Such a phenomenon is called magnitude saturation, which leads us underestimating the true magnitude of large and also devastating earthquakes. In order to calculate the magnitude closer to the real magnitude, immediately after an earthquake, the near-field and low-frequency information from the source are important and necessary. Global Positioning System (GPS) takes advantage on the resolving power of low-frequency rupture behavior and overcomes the records clipping in the near-field, which is an ideal instrument for large earthquake. In order to calculate the focal mechanism, source location, and magnitude in a few seconds following an earthquake, this research builds a GPS-based focal mechanism inversion method for Taiwan. To test whether the model works properly, I test three local magnitudes ML >6 earthquakes occurred in 2013, Taiwan. Two earthquakes are of ML 6.2 and 6.5 occurred in Nantou County, in the central Taiwan with close epicentral locations within a distance about 8.5 km, namely the 0327 and 0602 earthquakes, respectively. Another earthquake occurred near Ruisui town, in the eastern Taiwan with ML 6.4, called the Ruisui earthquake. I also test two additional events for a larger occurred in 2002 of ML 6.8, called 331 earthquake; and the other occurred in 2003 of ML 6.4, called Chengkung earthquake. All the results showed good agreements with the results from GCMT and BATS, which evaluate the source parameters from dynamic wave information. Such success shows that GPS measurements alone can provide important information for inverting earthquake source model parameters.
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Mustac, Marija. "Hierarchical Bayesian Inversion for the Point Source Moment Tensor: Method and Applications." Phd thesis, 2016. http://hdl.handle.net/1885/113632.
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One of the most important aspects of seismology is explaining the
generation of seismic waves during earthquakes. The first
mathematical models of earthquakes involved shear faulting, where
deformation of rocks surrounding the fault increases the stress
level, causes rock fracturing and results in radiation of elastic
waves. Over the years, a large number of earthquakes that cannot
be explained only with shear faulting have been observed. Hence,
the mathematical model of seismic sources evolved into a seismic
moment tensor (MT), which also includes isotropic and compensated
linear vector dipole components. Although uncertainties in MT
inversions are important for estimating solution robustness, they
are rarely available. Furthermore, noise in the data can alter
the waveform and cause spurious non-double-couple components.
In this thesis, I address these issues using Bayesian
hierarchical inversion, a relatively novel technique in
seismology. Its probabilistic approach gives an ensemble of
solutions instead of just one best-fit solution, thus, it can be
used to estimate MT uncertainties. The algorithm developed as a
part of this thesis uses waveform data of regional earthquakes
and explosions with moderate magnitudes to compute the centroid
location and the seismic moment tensor. The algorithm includes a
sophisticated treatment of data noise utilising an empirical
noise covariance matrix, and including the level of noise as an
unknown in the inversion. As a result, the model complexity is
determined by the data themselves.
There are two major groups of events for which the Bayesian
approach can be of great importance, and to which the algorithm
has been applied. The first one is seismic events in complex
geological environments, such as volcanic and geothermal areas. A
significant number of these events are expected to have source
processes that require the full MT. The second group is
explosions, where the algorithm can be valuable for nuclear
proliferation. The feasibility of the approach is initially
demonstrated on synthetic data contaminated with noise. It is
shown that the empirical covariance matrix improves the location
estimate. This is followed by application to a well-studied
earthquake from Long Valley caldera, a volcanic environment in
California, where a statistically significant isotropic component
of the source is confirmed.
The method was further improved to include multiple noise
parameters that determine the fit on each record, and in turn
weight the stations' contribution in the inversion. Subsequently,
I have analysed several earthquakes from a geothermal field in
California, The Geysers. The double-couple components of the
sources agree well with the regional stress field, but the
non-double-couple components show a variety of values.
Finally, the method is applied to the 2013 Democratic People's
Republic of Korea nuclear explosion. Since the paths to the
recording stations in the region traverse significantly different
crustal structures, a linear inversion was initially conducted to
create a composite structural model that better explained the
oceanic raypaths. The Bayesian inversion shows exceptionally low
uncertainties in the moment tensor solution for this event,
characterising it as a crack mechanism, which explains the
non-isotropic radiation as a result of material damage.
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Davies, John Huw. "Some problems in mantle structure and dynamics. Part I. Inversion for depth variation of spectra of mantle compressional and shear velocity heterogeneity. Part 2. Physical model of source region of subduction zone volcanism." Thesis, 1990. https://thesis.library.caltech.edu/6048/1/Davies_jh_1990.pdf.
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Part 1. The scatter in ISC P- and S-wave travel-time residuals was inverted to give a measure of the data-set's incoherent noise and the depth variation of the spectra of the Earth's seismic heterogeneity. The P- and S-wave models are similar in pattern with most of their power shallower than 400km. The power generally decreases with depth and is lowest around 1500-2600km depth. Both models show a slight increase locally below the 670km discontinuity. The long-wavelength half-width (l<50) is around 500km through the upper mantle increasing to around 1200km in the lowermost mantle. The variance in the travel-time residuals requires that (δ1nV_s/ δ1n V_p) ≈ 2, if they are correlated. Our results suggest values as high as 5 from 60-1400km; these could be correct but our preferred explanation is that it's a result of poor depth resolution of the shallowest layer and a difference in the spectral resolution of the two studies.
Part 2. Thermal modeling of a generic subduction zone suggests that the oceanic crust does not melt extensively to be the source of subduction zone magmas. The slab dehydrates and the water is transported laterally into the wedge by a mechanism involving transport fixed in amphiboles and vertical porous flow when free. This water generates melting at the amphibole saturated solidus. Melting reaches a maximum at the hottest geotherm, which also caps the source region. Melts depart the source region in cracks whose direction of propagation is perpendicular to the least compressive stress. For a corner flow regime this leads to focusing of melt towards the wedge corner. The model correctly predicts the location of, the volcanic front. The melt and residue provide buoyancy that leads to local flow reversal and modulates the volcanism with a period of ≈ 1Ma. Estimates suggest more water is subducted than reappears in extrusive volcanics. We suggest the excess water is stored in melts trapped deeper in the section that later become the precursors of granitic and tonalitic plutons.
Book chapters on the topic "Source depth and mechanism inversion"
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Zollo, Aldo, and Pascal Bernard. "Nonlinear Inversion of S-Wave Polarization for Constraining the Source Mechanism of Small Earthquakes." In IAVCEI Proceedings in Volcanology, 248–66. Berlin, Heidelberg: Springer Berlin Heidelberg, 1992. http://dx.doi.org/10.1007/978-3-642-77008-1_19.
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Masri, Firas, and Mahmoud Abdelrahman. "An Explorative Study of Knowledge-Transfer Mechanism." In Handbook of Research on Implementing Knowledge Management Strategy in the Public Sector, 18–54. IGI Global, 2019. http://dx.doi.org/10.4018/978-1-5225-9639-4.ch002.
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The practice of the healthcare including treatment, policy planning and decisions, should be based on evidences (explicit) and experience (tacit) whenever possible. This might be achieved through investment in studying knowledge management (KM) in the healthcare practice. However, the studies of KM in practice and specifically in the healthcare are still limited, because literature keeps looking at KM from the angle of technological solution without considering KM functions from the social aspects. Thus, this chapter tries to provide an in-depth framework to a specific and fundamental function of the KM, which is knowledge transfer. This chapter proposes a conceptual framework of a multilevel process-based on enablers and barriers of KT mechanism. This chapter moderates the KT mechanism into five main elements related to characteristics of knowledge: source, recipient, relationships between them, tools, and context of the actual transfer. This model is conducted to notify the design and implementation of KT systems and mechanisms for public organizations, including healthcare.
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Furlotte, Wes. "The Nightmare of Reason and Regression into the Night of the World." In The Problem of Nature in Hegel's Final System, 119–39. Edinburgh University Press, 2018. http://dx.doi.org/10.3366/edinburgh/9781474435536.003.0008.
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This chapter critically reads finite subjectivity in terms of its natural, instinctual dimension. The chapter’s objective is to further substantiate the significant problem Hegel’s conception of nature poses to his project of radical freedom. Developing a sense of subjectivity’s potential for “regression”, the chapter seeks to outline how, as in the case of acute psychopathology, subjectivity’s ordering of its instinctual dimension might be undermined. Hegelian regression, therefore, is a haywire inversion where the logical superiority of spirit’s freedom is subordinated to the ontologically prior register of instinct. Extrapolating from this analysis, the chapter contends that the unconscious-instinctual depth of the subject is never entirely abandoned; this abyss (Schacht) of indeterminacy lingers within the matrices of finite spirit and has the perpetual possibility of breaking-loose to the detriment of subjectivity’s free self-actualizing activity. Consequently, a reconstruction of Hegel’s account of mental illness forcefully demonstrates how nature remains a perpetual source of trauma for finite subjectivity and, therefore, the life of spirit.
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Zhao, Yi-Fan, Hua Li, Hung-Ming Chang, Chih-Chung Lin, Shinn-Dar Wu, and Chia-Ming Chang. "Research on the Reciprocating Motion of the Man-Machine Indirect Piston and the Efficiency of Internal Friction." In Advances in Transdisciplinary Engineering. IOS Press, 2021. http://dx.doi.org/10.3233/atde210344.
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In the process of technological progress and development, many industries are moving towards artificial intelligence (AI) technology, which is a construction and combination of multi-thinking technology. But in terms of structure, material development and diversification, the source of ideas is still inseparable from the natural world. Therefore, when faced with solving problems, many scientists not only conduct in-depth research on changes in cells, tissues and expansion, to solve the multi-dimensional movement of current technology, but also non-destructively explore the thermal effects of friction. Self-generated lubrication or external additives are used to solve the demand, so that the reciprocating movement of the piston can be more effective, and each cycle can be achieved. According to research and discussion, in each cycle, heat engine and cooling, speed movement frequency and lubrication method are different, which not only makes the piston have different effects, but also the reaction and sensitivity will greatly change, which makes it necessary to stop resting. Therefore, this research is primarily aimed at exploring the reciprocating motion of the human-machine “Indirect piston” and the efficiency of internal friction. The purpose is to have a more in-depth study of the piston theory, so as to have a deeper foundation for the movement of derived multi-dimensional angles in the future. In the future, there will be better development in injection, piston mechanism, and lubrication.
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Kilifarska, Natalya, Volodymyr Bakhmutov, and Galyna Melnyk. "Coupling between Geomagnetic Field and Earth’s Climate System." In Magnetosphere [Working Title]. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.103695.
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The idea about synchronized variations of geomagnetic field and climate appears in the middle of the twentieth century. Among others, one of the main reasons for its unpopularity is the missing mechanism of coupling between magnetic and non-magnetic media. This chapter offers such a mechanism, consisting of a chain of relations transmitting the geomagnetic spatial-temporal variations down to the planetary surface. The first element of this chain is energetic particles propagating in Earth’s atmosphere, whose density and depth of penetration are modulated by geomagnetic field. Thus, the non-dipolar geomagnetic irregularities are projected on the ionization layer in the lower atmosphere (known as Regener-Pfotzer maximum). This unevenly distributed ionization, in certain conditions (i.e. dry atmosphere), acts as a secondary source of ozone near the tropopause. Ozone at this level is of special importance due to its influence on the tropopause temperature and humidity, and consequently on the planetary radiation balance. Hence, the geomagnetic spatial and temporal variations are imprinted down to the surface, impacting the climate system and its regional structures. The chapter provides synthesized information about geomagnetic field variability, particles’ propagation in Earth’s atmosphere, ion-molecular reactions initiating ozone formation in the lower stratosphere, as well as evidence for its covariance with some atmospheric variables.
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Xu, Huifang, Kuang-Sheng Hong, Meiye Wu, and Seungyeol Lee. "Tectonic hydrogen and tectonic oxygen production through deforming piezoelectric minerals in the presence of water." In In the Footsteps of Warren B. Hamilton: New Ideas in Earth Science. Geological Society of America, 2022. http://dx.doi.org/10.1130/2021.2553(12).
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ABSTRACT A high concentration of hydrogen gas occurs in fracture zones of active faults that are associated with historical earthquakes. To explain the described phenomenon, we propose the piezoelectrochemical (PZEC) effect as a mechanism for the direct conversion of mechanical energy to chemical energy. When applied to natural piezoelectric crystals including quartz and serpentine, hydrogen and oxygen are generated via direct water decomposition. Laboratory experiments show H2 gas is generated from strained piezoelectric material due to the extremely low solubility of H2, suggesting that the deformed or strained mineral surfaces can catalyze water decomposition. If the strain-induced H2 production is significant, hydrogen measurements at monitoring sites can offer information on deformation of rocks operating at depth prior to earthquakes. Oxygen can be measured in water due to its high solubility compared to hydrogen. Our experimental results demonstrate that dissolved oxygen generated from the PZEC effect can oxidize dissolved organic dye and ferrous iron in an aqueous Fe(II)–silicate metal complex. The hydrogen and oxygen formed through stoichiometric decomposition of water in the presence of strained or deformed minerals in fault zones (including subduction zones and transform faults) may be referred to as tectonic hydrogen and tectonic oxygen. Tectonic hydrogen could be a potential energy source for deep subsurface and glacier-bedrock interface microbial communities that rely on molecular hydrogen for metabolism. Tectonic oxygen may have been an important oxidizing agent when dissolved in water during times in early Earth history when atmospheric oxygen levels were extremely low. Reported “whiffs” of dissolved oxygen before the Great Oxidation Event might have been related to tectonic activity.
Conference papers on the topic "Source depth and mechanism inversion"
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Zhang, Hongliang, Jubran Akram, Jan Dettmer, and Kristopher A. Innanen. "Bayesian source-mechanism inversion for microearthquakes." In First International Meeting for Applied Geoscience & Energy. Society of Exploration Geophysicists, 2021. http://dx.doi.org/10.1190/segam2021-3583596.1.
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Li*, Zhao, and Evgeni Chesnokov. "Source mechanism inversion in an anisotropic physical model." In SEG Technical Program Expanded Abstracts 2014. Society of Exploration Geophysicists, 2014. http://dx.doi.org/10.1190/segam2014-0754.1.
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Jang, Iktae, Hitoshi Mikda, and Junichi Takekawa. "Estimating the earthquake source mechanism using full waveform inversion." In The 23rd International Symposium on Recent Advances in Exploration Geophysics (RAEG 2019). European Association of Geoscientists & Engineers, 2019. http://dx.doi.org/10.3997/2352-8265.20140243.
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Foss, Clive. "Parametric inversion as an advanced technique for magnetic source depth estimation." In SEG Technical Program Expanded Abstracts 2006. Society of Exploration Geophysicists, 2006. http://dx.doi.org/10.1190/1.2370412.
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Neagoe, Cristian. "FOCAL MECHANISM AND SOURCE DIRECTIVITY FOR VRANCEA INTERMEDIATE DEPTH EARTHQUAKES." In 17th International Multidisciplinary Scientific GeoConference SGEM2017. Stef92 Technology, 2017. http://dx.doi.org/10.5593/sgem2017/14/s05.017.
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GAO, T. F., and E. C. SHANG. "THE OPTIMUM SOURCE DEPTH DISTRIBUTION FOR REVERBERATION INVERSION IN A SHALLOW-WATER WAVEGUIDE." In Proceedings of the 7th International Conference (ICTCA 2005). WORLD SCIENTIFIC, 2006. http://dx.doi.org/10.1142/9789812772602_0006.
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Zhang*, Xiong, Wei Zhang, and Jie Zhang. "Elastic full waveform inversion of microseismic data for location and source mechanism." In SEG Technical Program Expanded Abstracts 2014. Society of Exploration Geophysicists, 2014. http://dx.doi.org/10.1190/segam2014-1223.1.
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Feng, Runhua, Shoaib Memon, Lingping Zeng, Quan Xie, Suzie Qing Jia, Hongliang Zhang, Daijun Du, Wanfen Pu, Joel Sarout, and Mohammad Sarmadivaleh. "Source Mechanism and Stress Inversion for Hydraulic Fracturing Induced Microseismicity in Glutenite Reservoir." In SPE/IATMI Asia Pacific Oil & Gas Conference and Exhibition. Society of Petroleum Engineers, 2019. http://dx.doi.org/10.2118/196456-ms.
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Anggono, T., S. Syuhada, F. Febriani, B. Soedjatmiko, A. Amran, A. D. Prasetio, and C. N. Dewi. "Source mechanism identification of 2019/02/02 Southern Sumatra earthquake from regional waveform inversion." In INTERNATIONAL CONFERENCE ON TRENDS IN MATERIAL SCIENCE AND INVENTIVE MATERIALS: ICTMIM 2020. AIP Publishing, 2020. http://dx.doi.org/10.1063/5.0014499.
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Lu, Wangtao, Jianliang Qian*, and Robert Burridge. "Babich-expansion based Fast Huygens Sweeping Methods for Point-source Helmholtz Equations." In 2015 Workshop: Depth Model Building: Full-waveform Inversion, Beijing, China, 18-19 June 2015. Society of Exploration Geophysicists, 2015. http://dx.doi.org/10.1190/fwi2015-024.
Full textReports on the topic "Source depth and mechanism inversion"
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Plourde, A. P., and J. F. Cassidy. Mapping tectonic stress at subduction zones with earthquake focal mechanisms: application to Cascadia, Japan, Nankai, Mexico, and northern Chile. Natural Resources Canada/CMSS/Information Management, 2022. http://dx.doi.org/10.4095/330943.
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Earthquake focal mechanisms have contributed substantially to our understanding of modern tectonic stress regimes, perhaps more than any other data source. Studies generally group focal mechanisms by epicentral location to examine variations in stress across a region. However, stress variations with depth have rarely been considered, either due to data limitations or because they were believed to be negligible. This study presents 3D grids of tectonic stress tensors using existing focal mechanism catalogs from several subduction zones, including Cascadia, Japan, Nankai, Mexico, and northern Chile. We bin data into 50 x 50 x 10 km cells (north, east, vertical), with 50% overlap in all three directions. This resulted in 181380 stress inversions, with 90% of these in Japan (including Nankai). To the best of our knowledge, this is the first examination of stress changes with depth in several of these regions. The resulting maps and cross-sections of stress can help distinguish locked and creeping segments of the plate interface. Similarly, by dividing the focal mechanism catalog in northern Japan into those before and those &gt;6 months after the 2011 Mw 9.1 Tohoku-Oki earthquake, we are able to produce detailed 3D maps of stress rotation, which is close to 90° near the areas of highest slip. These results could inform geodynamic rupture models of future megathrust earthquakes in order to more accurately estimate slip, shaking, and seismic hazard. Southern Cascadia and Nankai appear to have sharp stress discontinuities at ~20 km depth, and northern Cascadia may have a similar discontinuity at ~30 km depth. These stress boundaries may relate to rheological discontinuities in the forearc, and may help us unravel how forearc composition influences subduction zone behaviour and seismic hazard.