Journal articles: 'Seismic sequences'

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Kamiludin, Udaya, I. Nyoman Astawa, and Moch Akrom Mustafa. "INDIKASI KETERDAPATAN ENDAPAN PLASER PEMBAWA TIMAH DAN UNSUR TANAH JARANG (REE), DI PERAIRAN TODAK, SINGKEP, KEPULAUAN RIAU." JURNAL GEOLOGI KELAUTAN 13, no. 2 (February 16, 2016): 109. http://dx.doi.org/10.32693/jgk.13.2.2015.266.

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Penelitian geofisika di Perairan Todak, Singkep, Kepulauan Riau menggunakan seperangkat peralatan seismik pantul dangkal saluran tunggal. Tujuan penelitian ini adalah untuk menunjang penelitian keterdapatan endapan plaser pembawa timah dan unsur tanah jarang (REE). Hasil interpretasi rekaman seismik diperoleh terdapatnya lembah/mangkuk yang terbentuk secara alami akibat adanya terobosan batuan granit, di mana lembah/mangkuk-mangkuk ini merupakan tempat terjadinya sedimentasi dari hasil pelapukan batuan di sekitarnya. Hasil interpretasi rekaman seismik pantul saluran tunggal analog di perairan Todak, Singkep, dapat diklasifikasikan menjadi 3 runtunan yaitu runtunan A, B, dan runtunan C.Kata kunci Data seismik, endapan plaser, lembah/mangkuk, Perairan Todak. Geophysical research at Todak, Singkep, Riau Archipelago Province, by using single channel sahllow seismic refletion. The purpose of research is to support placer deposit bearing tin and rare earth element research at this area. From seismic interpretation can be recognized the distribution of valley/bowls which is naturally formed, caused by granite rock intrusion. Those valleys are sedimentation places of wheathered rock from the surrounding area. Beside that, the seismic research also for determining the placer deposit thickness. Interpratation of analog single channel seismic records in the Todak waters, Singkep, result 3 seismic sequences and intrusive feature, A sequences, B, and C. Keywords: Seismic data, placer deposit, valley/basin, Todak Watres.

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Telesca, Luciano, and Vincenzo Lapenna. "Measuring multifractality in seismic sequences." Tectonophysics 423, no. 1-4 (September 2006): 115–23. http://dx.doi.org/10.1016/j.tecto.2006.03.023.

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Telesca, Luciano. "Nonextensive analysis of seismic sequences." Physica A: Statistical Mechanics and its Applications 389, no. 9 (May 2010): 1911–14. http://dx.doi.org/10.1016/j.physa.2010.01.012.

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Valerio, Emanuela, Vincenzo De Novellis, Mariarosaria Manzo, and Pietro Tizzani. "Fractal Study of the 1997–2017 Italian Seismic Sequences: A Joint Analysis of Seismological Data and DInSAR Measurements." Remote Sensing 11, no. 18 (September 11, 2019): 2112. http://dx.doi.org/10.3390/rs11182112.

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During the last 20 years (1997 to 2017), four seismic sequences with Mw ≥ 5.5 mainshocks nucleated along the Central and Northern Apennines chain (Italy), causing casualties and damage: the 1997 Colfiorito, the 2009 L’Aquila, the 2012 Emilia, and the most recent 2016–2017 Central Italy seismic sequences. In this work, we perform a novel joint analysis of seismological and remote-sensing data to achieve new insights into the faulting process evolution during the considered seismic sequences. To this aim, we study these seismic sequences by exploiting the available seismological data and by applying fractals theory to them. In particular, we characterize the different behavior of compressional and extensional seismic sequences by examining the temporal evolution of the fractal dimension values. In addition, we compare the Differential Synthetic Aperture Radar Interferometry (DInSAR) displacement maps relevant to the considered seismic events (already published in our past papers) and the performed spatial and temporal seismological analyses, in order to emphasize some significant aspects of the different faulting processes active during these Italian seismic sequences. The analysis of the fractal dimension values shows that over time extensional seismic sequences are spatially distributed within a volume, whereas compressional ones are aligned along a preferential surface. These spatio-temporal patterns are confirmed by: (1) the spatial distribution of hypocenters for the events that occurred between the mainshock and the post-seismic synthetic aperture radar (SAR) acquisition; (2) the spatial extension of coseismic DInSAR ground-deformation patterns. The proposed seismic and ground-deformation analyses can thus typify different geodynamic contexts in Italy, providing a distinct image of articulated faulting processes.

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TELESCA, LUCIANO, VINCENZO CUOMO, VINCENZO LAPENNA, and MARIA MACCHIATO. "1/fα FLUCTUATIONS OF SEISMIC SEQUENCES." Fluctuation and Noise Letters 02, no. 04 (December 2002): L357—L367. http://dx.doi.org/10.1142/s021947750200097x.

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We investigate the time dynamics of sequences of earthquakes occurred in three different seismic zones in Italy. All the series analyzed present 1/f α temporal fluctuations, shown by the power-law behaviour of several statistics (Fano Factor, Allan Factor and Count-based Periodogram), that allow to detect correlation properties in point processes.

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Scott, R. W. "Are seismic/depositional sequences chronostratigraphic units?" Paleontological Society Special Publications 6 (1992): 264. http://dx.doi.org/10.1017/s2475262200008248.

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Sequence Stratigraphic Analysis is claimed to be a “new globally valid system of stratigraphy … a precise methodology to subdivide, correlate and map sedimentary rocks” (Vail et al., 1991, p. 622). Sequence stratigraphic units, such as depositional sequences, depositional systems tracts, and parasequences, are time-equivalent rocks of specific durations controlled by cyclical changes in sediment supply related to eustasy. These units are bounded by regionally extensive unconformities with erosion beneath and onlapping strata above, or by physical surfaces separating either different patterns of stratal geometry or shoaling-up facies units. According to this school, precise correlations are based upon inferred time relations within depositional models.Several key concepts of sequence stratigraphy have their origins in early geological studies. For many years geologists have separated time-equivalent strata by regional unconformities related to changes in climate or sea level, e.g., J. Woodward, 1695 and T. C. Chamberline, 1909. Stratal surfaces, such as bentonites and limestone markers, have been used in place of fossils for time correlations since the first wells were drilled. Stratigraphic models have strongly influenced how we correlate strata since the time of William Smith.Two developments are, indeed, new and have sparked the current resurgence in stratigraphic research. One is the seismic technology to test the physical continuity of strata on a regional scale (50-100 km), and to test the stratal geometry of genetically related depositional packages. The second is the chart of global coastal onlap events and eustasy (Haq et al., 1988).Some key research problems are: (1) how to identify unique, time-significant stratal surfaces; (2) how to test their physical continuity; (3) how to test the time relations within depositional models; and (4) how to identify the unique, time-significant global events recorded in the stratigraphic record. These stratigraphic concepts can be tested by graphic correlation, which is a powerful technique of high precision, quantitative stratigraphy. Its application in Cretaceous sections of the Gulf Coast and Oman, and in the Plio-Pliestocene of the Gulf Coast aids the distinction between synchronous surfaces and diachronous boundaries.

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Gentili, Stefania. "Radiated energy evolution during seismic sequences." Physics of the Earth and Planetary Interiors 196-197 (April 2012): 49–61. http://dx.doi.org/10.1016/j.pepi.2012.02.003.

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Kusnida, Dida, and Tommy Naibaho. "LATE NEOGENE SEISMIC STRUCTURES OF THE SOUTH BATANTA BASIN, WEST PAPUA." BULLETIN OF THE MARINE GEOLOGY 29, no. 1 (February 15, 2016): 11. http://dx.doi.org/10.32693/bomg.29.1.2014.61.

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Study on multi-channel seismic records from South Batanta Basin, West Papua acquired during RV Geomarin III cruise in 2013 were aimed to invent and map geological aspects and for geo-tectonic and geological history studies. Seismic data indicate that sediment sequences which can be observed from our seismic system in the study area are characterized by pre-extension sediments (Lower Early Miocene-Upper Early Pliocene), syn-extension sediments (Lower Middle Pliocene-Upper Late Pliocene), post-extension sediments (Early Pleistocene), and syn-inversion sediments (Late Pleistocene-Recent) typical of the West Papua tectonic system. In the study area, sediment sequences are possibly characterized by clastical sedimentary cover such as slumps, debrites and turbidites. Key words: South Batanta Basin, seismic sequence, tectonic, faults, clastical sediments. Studi rekaman seismik multi kanal dari Cekungan Batanta Selatan, Papua Barat yang diperoleh selama pelayaran KR Geomarin III pada tahun 2013 bertujuan untuk menginventarisir dan memetakan aspek-aspek geologi serta untuk studi geo-tektonik dan sejarah geologi. Data seismik menunjukkan bahwa urutan sedimen yang dapat diamati dari sistem seismik di daerah studi ditandai oleh sedimen pra-ekstensi (Miosen Awal Bagian Bawah-Pliosen Awal Bagian Atas), sedimen syn-ekstensi (Pliosen Tengah Bagian Bawah-Pliosen Akhir Bagian Atas), sedimen post-ekstensi (Plestosen Awal), dan sedimen syn-inversi (Pleistosen Akhir-Resen) tipikal sistem tektonik Papua Barat. Di daerah studi, urutan sedimen dicirikan oleh sedimen penutup klastika kemungkinan berupa slump, debrit dan turbidit. Kata kunci: Cekungan Batanta Selatan, sekuen seismik, tektonik, sesar, sedimen klastika.

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Kontorovich, V. A., D. V. Ayunova, S. M. Guseva, L. M. Kalinina, A. Yu Kalinin, M. S. Kanakov, M. V. Soloviev, E. S. Surikova, and T. N. Toropova. "SEISMIC AND GEOLOGICAL CHARACTERISTICS OF SEDIMENTARY SEQUENCES AND PETROLEUM POTENTIAL OF THE YAMAL, GYDAN AND SOUTH KARA PETROLEUM AREAS (Arctic regions of West Siberia, the Kara Sea shelf)." Russian Journal of geophysical technologies, no. 4 (March 6, 2019): 10–26. http://dx.doi.org/10.18303/2619-1563-2018-4-3.

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There are six sedimentary seismic sequences overlying pre-Mesozoic basement in the Mesozoic-Cenozoic sedimentary cover of the Arctic regions of West Siberia and the Kara Sea shelf. The paper describes the seismic markers characteristics and the seismic-facial features of the Paleozoic, Triassic, Jurassic, Neocomian, Apt-Cenomanian and TuronianCenozoic seismic sequences. It was concluded that the features of large Cenomanian gas pools are seismic markers associated with gas-water contacts; Apt-Albian pools are displayed on time sections by a bright spot seismic anomaly.

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Situmorang, Dr B. "Seismic Stratigraphy Of The Makassar Basin." Scientific Contributions Oil and Gas 10, no. 1 (April 14, 2022): 3–38. http://dx.doi.org/10.29017/scog.10.1.895.

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Seismic reflection profiles from the Makassar basin have been analysed in terms of seismic stratigraphy. Systematic patterns of reflection terminations indicate the existence of at least three surfaces of discontinuity across the profiles-designated in order of superposition as C1, C2 and C3 - which define the boundaries of four seismic sequences, ie. :- seismic sequence I : topped by C1- seismic sequence II : the interval between C1 and C2- seismic sequence III : the interval between C2 and C3- seismic sequence IV : the interval between Cz and the sea floor Seismic sequence II is dominated by basin slope and basin floor seismic facies whereas seismic sequences II and IV consist of mainly shelf and shelf margin seismic facies. Correlation of seismic sequences with well data facilitates the exposition of basin development, The Late Cretaceous-early Tertiary regional uplift and erosion produced a major unconformity C1, upon which the transgressive facies of seismic sequence II was deposited. A lowstand of sea level due to the so-called intra-Mio- cene orogeny occurred in the upper Early Miocene and produced the C2. Deposition of seismic sequence III is marked by a relative rise of sea level, probably followed by another lowstand of sea level during Mio-Pliocene which formed the C3. The final event is an overall transgression and deposition of seismic sequence IV, with a possible minor lowstand of sea level in Pliocene-Recent, The occurrence of basin slope and basin floor seismic facies within seismic sequence II suggests that in the pre-Lower Miocene, basin subsidence was slightly greater than the rate of depositions. Since Lower Miocene both subsidence and sedimentation rates were equal and the deposition of shelf and shelf margin seismic facies of seismic sequences III and IV was prevailed in the basin.

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Wharton, Stanley Rich. "Seismic chronostratigraphy and basin development at a Mid-Cretaceous intrashelf basin margin." Interpretation 3, no. 2 (May 1, 2015): SN1—SN20. http://dx.doi.org/10.1190/int-2014-0132.1.

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The Mid-Cretaceous Wasia Formation represents one of the most productive hydrocarbon carbonate sequences in the Middle East. In Saudi Arabia, limited integrated studies have assessed the complexity and spatial distribution of its reservoir depositional systems near to an intrashelf basin margin. This study was focused on an assessment of its 3D seismic chronostratigraphy by integrating key well and seismic data to evaluate the gross depositional history of the mixed carbonate-clastic system. A seismic chronostratigraphy approach was introduced to assess the geometric relationships of depositional cycles and lithologic associations in response to relative sea-level changes. The main step entailed the correlation of well log chronostratigraphy from core and biostratigraphy interpretations with closely spaced, semiautomatically generated seismic horizons from seismic reflection data. A 3D seismic chronostratigraphy cube was built to interactively assess the basin history through the Mid-Cretaceous stages. Seismic sequences were selected to assess isopachs and gross depositional trends for demarcation of shelf, shelf margin, and slope from horizon attributes including root-mean-square amplitude and frequency decomposition. The results found the oldest Albian Safaniya member to be a generalized low-angle ramp shelf slope with thinning of sequences toward an intrashelf basin. Later, in the Albian, Cenomanian, and Turonian, carbonate factories developed distinct seismic sequences with steepened prograding systems in the Mauddud, Ahmadi/Rumaila, and Mishrif members at the intrashelf basin margin. Generally, areas immediately landward of the shelf margin possessed the most favorable reservoir lithologies of rudist-bearing platform carbonates, with source-rock distribution confined to basinal equivalents of sequences. The seismic chronostratigraphy approach proved to be fundamental to understanding the Wasia carbonate depositional system because it provided a technique to assess the varied stratal architectures of the main productive sequences. The integrated technique represents a unique methodology for exploration targeting of conventional reservoirs and unconventional source rocks.

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Aras, Fuat, and Ekber Düzci. "Seismic Performance of Traditional Stone Masonry Dwellings under Çanakkale Seismic Sequences." Journal of Performance of Constructed Facilities 32, no. 4 (August 2018): 04018029. http://dx.doi.org/10.1061/(asce)cf.1943-5509.0001173.

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Zhai, Chang-Hai, Zhi Zheng, Shuang Li, and Li-Li Xie. "Seismic analyses of a RCC building under mainshock–aftershock seismic sequences." Soil Dynamics and Earthquake Engineering 74 (July 2015): 46–55. http://dx.doi.org/10.1016/j.soildyn.2015.03.006.

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Adeleye, Mutiu Adesina, Kazeem Oladayo Yekeen, and Sikiru Adetona Amidu. "Seismic stratigraphic analysis for hydrocarbon exploration in the Beta Field, Coastal Swamp Depobelt, Niger Delta." Geology, Geophysics and Environment 46, no. 4 (December 22, 2020): 259–71. http://dx.doi.org/10.7494/geol.2020.46.4.259.

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Hydrocarbon exploration analysis from a seismic stratigraphic approach was carried out within the Beta Field, Coastal Swamp Depobelt, Niger Delta, to identify system tracts and sequence boundaries that could be associated with potential hydrocarbon accumulation. 3D seismic volume and data from four wells were analyzed. Depositional sequences, system tracts, sequence boundaries, and candidate maximum flooding surfaces were picked from logs, while reflection patterns and terminations were interpreted from seismic sections. Log shapes from gamma rays in combination with seismic facies analysis were interpreted in order to delineate lithology, depositional environments and depositional sequences. Seismic attributes were extracted and were draped on gridded surfaces from the interpreted seismic horizons. These were integrated with structure maps to obtain structural and stratigraphic trends, and the possible presence of reservoir sand. Five depositional sequences and nine seismic facies were identified within the field. The depositional sequences were designated Sequences S1 to S5 based on the depth of the occurrences and stacking patterns. This study reveals a progression from fluvial depositional settings to the shelf. The main reservoirs identified are the sand units of the highstand and lowstand within three depositional sequences (S1, S4 and S5) although interbedded sands within the TST of S4 and S5 are also suspected of being potential reservoirs. The channel sand deposits within the study area are suspected to be hydrocarbon bearing as they occurred within the complex fault trapping system popular in the Niger Delta. The application of seismic stratigraphy, as shown in this study, serves to encourage exploration in the Niger Delta where it could be effectively employed for reducing risk in hydrocarbon exploration.

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Gramstad, Oddgeir, Jan Oystein Haavig Bakke, Lars Sonneland, and Carlos Eduardo Abreu. "Simultaneous extraction of stratigraphic sequences using iterative seismic DNA detection." Interpretation 2, no. 4 (November 1, 2014): T167—T176. http://dx.doi.org/10.1190/int-2014-0069.1.

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We developed a new stratigraphic interpretation methodology enabling extraction of stratigraphic sequences of surfaces. This methodology consisted of two main components. The first component was inspired by DNA search technology used in bioinformatics in which the goal was to detect base-pair sequences in DNA molecules. The base-pair sequences may be modified by mutations, so the search technology must be able to take such mutations into account. We have adapted this technology to search for seismic reflection sequences, acknowledging that seismic reflections were likely to vary laterally that were somewhat analogs to mutations in bioinformatics. One example of a seismic reflection sequence was a geologically sorted sequence of seismic reflectors. The second component of the workflow was how to connect the DNA hits into continuous surfaces. A quality metric was used to steer the connection process of the DNA hits in a sorted order. This workflow enabled the user to extract a sequence of surfaces simultaneously, which is crucial in seismic stratigraphic interpretation.

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Zeng, Hongliu, Xiaomin Zhu, and Rukai Zhu. "New insights into seismic stratigraphy of shallow-water progradational sequences: Subseismic clinoforms." Interpretation 1, no. 1 (August 1, 2013): SA35—SA51. http://dx.doi.org/10.1190/int-2013-0017.1.

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Seismic clinoforms are the key building blocks for constructing the seismic stratigraphy of progradational depositional sequences. However, not all progradational systems are necessarily represented by seismic clinoforms. We evaluated the definition and interpretation of progradational systems that do not associate with seismic clinoforms. Nonclinoform (or subseismic clinoforms) seismic facies are mainly related to shallow-water deltas where the thickness of a prograding clinoform complex is too thin to be imaged as an offlapping reflection configuration. The clinoform detection limit for clinoform imaging is defined as one wavelength (the thickness of two seismic events) and is related to the predominant frequency of the seismic data and the velocity of the sediments. Three examples from the Songliao Basin of China and Gulf of Mexico illustrated ancient shallow-water deltas with various morphologies in lacustrine and marine environments by integrating the analysis of the core, wireline logs, and amplitude stratal slices made from nonclinoform seismic events. A seismic model of an outcrop carbonate clinoform complex in west Texas further demonstrated the seismic frequency control on clinoform seismic stratigraphy, including transitions between different types of clinoforms and between clinoforms and nonclinoform seismic facies. Ambiguity in interpreting nonclinoform seismic facies can be reduced by high-resolution acquisition, high-frequency enhancement processing, and seismic sedimentology.

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Vadeo, S. D., and M. V. Waghmare. "Non-linear Dynamic Analysis of RC Structures Under Earthquake Sequences." Proceedings of the 12th Structural Engineering Convention, SEC 2022: Themes 1-2 1, no. 1 (December 19, 2022): 373–78. http://dx.doi.org/10.38208/acp.v1.524.

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Earthquakes in active seismic regions usually occur in a series of medium to strong intensity ground motions at small intervals of times. A large intensity mainshock (MS) is often followed by a series of aftershocks (AS) or even preceded by smaller foreshocks. This sequence type of mainshock-aftershock (MS-AS) ground motions with varying intensity pose major seismic hazard as there is limited scope of repair and retrofitting between seismic events. Due to continuous and repeated seismic ground motions over a brief period of time, the damages in the structure gets accumulated and structure collapse. This study navigates the behaviour of reinforced concrete structures under such seismic sequences. For this purpose, the nonlinear response of three 12 storey reinforced concrete buildings (regular plan, mass irregularity and diaphragm irregularity) is evaluated. The buildings are subjected to five real seismic sequences from previous earthquakes. Nonlinear dynamic analyses are carried out to study the response of buildings under MS and MS-AS sequences considering: a) material and geometric non linearities and b) irregularities. A single highest aftershock is considered in the present study. The results in this study indicates that MS-AS seismic sequence considering both material and geometric nonlinearities has significant effect on the response of structure. It also showed that seismic sequences significantly alter the response of irregular structure.

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Mahat, Pushpa, Piyush Pradhan, Rabindra Adhikari, Andre Furtado, Dipendra Gautam, and Rajesh Rupakhety. "Seismic Sequence Vulnerability of Low-Rise Special Moment-Resisting Frame Buildings with Brick Infills." Applied Sciences 12, no. 16 (August 17, 2022): 8231. http://dx.doi.org/10.3390/app12168231.

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When buildings are exposed to earthquake sequence, damage aggravation is expected to occur. Although several studies report seismic vulnerability of reinforced concrete (RC) buildings under the mainshock–aftershock sequence, indicating damage aggravation due to aftershock, none, to the best of our knowledge, quantifies seismic vulnerability of buildings under foreshock–mainshock–aftershock sequences. Since foreshock–mainshock–aftershock sequences are also expected in many active seismic regions, we aim to quantify the level of vulnerability under seismic sequences considering the seismically highly active Himalayan region as the case study location. Fragility functions are derived considering foreshock, foreshock–mainshock sequence, and foreshock–mainshock–aftershock sequence for a low-rise special moment-resisting frame (SMRF) building that represents a typical low-rise owner-built construction system in Nepal, one of the most active seismic regions in the world. The results highlight that the foreshock significantly increases seismic vulnerability of the structures with respect to the often-considered case of a mainshock–aftershock sequence.

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Macurda, D. Bradford. "SEISMIC INTERPRETATION OF TRANSGRESSIVE AND PROGRADATIONAL SEQUENCES." Leading Edge 6, no. 4 (April 1987): 18–21. http://dx.doi.org/10.1190/1.1439383.

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Wang, L. X. "A neural detector for seismic reflectivity sequences." IEEE Transactions on Neural Networks 3, no. 2 (March 1992): 338–40. http://dx.doi.org/10.1109/72.125877.

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Chamoli, Ashutosh, and R. B. S. Yadav. "Multifractality in seismic sequences of NW Himalaya." Natural Hazards 77, S1 (September 7, 2013): 19–32. http://dx.doi.org/10.1007/s11069-013-0848-y.

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Rinaldin, Giovanni, and Claudio Amadio. "Effects of seismic sequences on masonry structures." Engineering Structures 166 (July 2018): 227–39. http://dx.doi.org/10.1016/j.engstruct.2018.03.092.

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Al-Masgari, Abd Al-Salam, Mohamed Elsaadany, Numair A. Siddiqui, Abdul Halim Abdul Latiff, Azli Abu Bakar, Sami Elkurdy, Maman Hermana, Ismailalwali Babikir, Qazi Sohail Imran, and Teslim Adeleke. "Geomorphological Geometries and High-Resolution Seismic Sequence Stratigraphy of Malay Basin’s Fluvial Succession." Applied Sciences 11, no. 11 (June 2, 2021): 5156. http://dx.doi.org/10.3390/app11115156.

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This study identified the Pleistocene depositional succession of the group (A) (marine, estuarine, and fluvial depositional systems) of the Melor and Inas fields in the central Malay Basin from the seafloor to approximately −507 ms (522 m). During the last few years, hydrocarbon exploration in Malay Basin has moved to focus on stratigraphic traps, specifically those that existed with channel sands. These traps motivate carrying out this research to image and locate these kinds of traps. It can be difficult to determine if closely spaced-out channels and channel belts exist within several seismic sequences in map-view with proper seismic sequence geomorphic elements and stratigraphic surfaces seismic cross lines, or probably reinforce the auto-cyclic aggregational stacking of the avulsing rivers precisely. This analysis overcomes this challenge by combining well-log with three-dimensional (3D) seismic data to resolve the deposition stratigraphic discontinuities’ considerable resolution. Three-dimensional (3D) seismic volume and high-resolution two-dimensional (2D) seismic sections with several wells were utilized. A high-resolution seismic sequence stratigraphy framework of three main seismic sequences (3rd order), four Parasequences sets (4th order), and seven Parasequences (5th order) have been established. The time slice images at consecutive two-way times display single meandering channels ranging in width from 170 to 900 m. Moreover, other geomorphological elements have been perfectly imaged, elements such as interfluves, incised valleys, chute cutoff, point bars, and extinction surfaces, providing proof of rapid growth and transformation of deposits. The high-resolution 2D sections with Cosine of Phase seismic attributes have facilitated identifying the reflection terminations against the stratigraphic amplitude. Several continuous and discontinuous channels, fluvial point bars, and marine sediments through the sequence stratigraphic framework have been addressed. The whole series reveals that almost all fluvial systems lay in the valleys at each depositional sequence’s bottom bars. The degradational stacking patterns are characterized by the fluvial channels with no evidence of fluvial aggradation. Moreover, the aggradation stage is restricted to marine sedimentation incursions. The 3D description of these deposits permits distinguishing seismic facies of the abandoned mud channel and the sand point bar deposits. The continuous meandering channel, which is filled by muddy deposits, may function as horizontal muddy barriers or baffles that might isolate the reservoir body into separate storage containers. The 3rd, 4th, and 5th orders of the seismic sequences were established for the studied succession. The essential geomorphological elements have been imaged utilizing several seismic attributes.

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Ruiz-García, Jorge, Edén Bojorquez, and Edgar Corona. "Seismic behavior of steel eccentrically braced frames under soft-soil seismic sequences." Soil Dynamics and Earthquake Engineering 115 (December 2018): 119–28. http://dx.doi.org/10.1016/j.soildyn.2018.08.018.

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Steeghs, Philippe, and Guy Drijkoningen. "Seismic sequence analysis and attribute extraction using quadratic time‐frequency representations." GEOPHYSICS 66, no. 6 (November 2001): 1947–59. http://dx.doi.org/10.1190/1.1487136.

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The variation of frequency content of a seismic trace with time carries information about the properties of the subsurface reflectivity sequence. As a result, analysis of the data in terms of the local frequency content can provide a worthwhile addition to the standard procedures that are used in seismo‐stratigraphic interpretation. The theory of quadratic time‐frequency representations provides a solid foundation for local frequency analysis of seismic data and seismic attribute extraction. Two applications of the quadratic time‐frequency representations are demonstrated: seismic sequence analysis and seismic attribute extraction. The joint time‐frequency representation of a seismic reflection pattern is often much more easily interpreted in terms of subsurface stratification than the time‐or frequency‐domain description alone. We show how the time‐frequency representation can be used to delineate seismic sequences on the basis of the time‐frequency characteristics of the signal. There exists a close relation between complex‐trace attribute analysis and quadratic time‐frequency representations. In the time‐frequency approach, the seismic attributes are characteristics of the local spectrum. Extraction of the attributes from the time‐frequency representation of the seismic trace leads to considerable improvement of the signal‐to‐noise ratio of the attributes. Furthermore, the classic set of seismic attributes of instantaneous amplitude, phase, and frequency can be easily extended with other parameters describing the local spectrum, such as instantaneous bandwidth, skewness, and kurtosis.

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Zhu, Hongtao, Zhiwei Zeng, Hongliu Zeng, Changgui Xu, and Fan Xiao. "Use of seismic-based new rose diagram to determine the major sediment-supply direction of progradational systems." GEOPHYSICS 84, no. 3 (May 1, 2019): IM11—IM18. http://dx.doi.org/10.1190/geo2018-0133.1.

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A conventional method for identifying sediment-supply directions is to characterize the seismic progradational reflection configuration, which is based mainly on qualitative observation of numerous seismic profiles. We have developed a more quantitative and practical way to determine the major sediment-supply direction (MSSD) using a new type of rose diagram based on seismic progradational sequence angles. In accordance with similar principles of the rose diagram used in structural geology, we have developed an analytical method and a workflow for a new rose diagram of seismic-based progradational sequence angles to determine MSSD. The Bozhong sag, a subbasin of the Bohai Bay Basin with two typical progradational sequences (I and II), provides a suitable example to analyze MSSD and test the new method. Our result indicates that the MSSD of the two progradational sequences (I and II) corresponds to azimuths of 10°–20° and 340°–350°, respectively, intuitively indicating two sequences derived from different provenance-transport systems. The new rose diagram of seismic progradational angles offers a powerful and quantitative method for seismic-based sedimentary provenance and paleocurrent analysis.

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Greene, Michael. "The discrete prolate spheroidal sequences and a series expansion for seismic wavelets." GEOPHYSICS 72, no. 6 (November 2007): V119—V132. http://dx.doi.org/10.1190/1.2783782.

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The discrete prolate spheroidal sequences (DPSSs) are a set of time-limited, band-limited, and mutually orthogonal sequences. I exploit their favorable properties to introduce a series expansion for seismic wavelets. By modifying the definition of the DPSSs, I generate new sequences that are tailored to the character of the seismic wavelet but retain the DPSSs’ favorable properties. I show that a series expansion composed of these new sequences can be thought of as a logical extension of a familiar practice, assuming the wavelet is a linear combination of a Ricker wavelet and its Hilbert transform ([Formula: see text] rotation). Two examples, one synthetic and one real, show how the series expansion can be used to tie well data to seismic data. This leads to a robust method to determine a wavelet. The examples also illustrate the properties of the series expansion, some of which can be related to familiar geophysical concepts such as thin-bed tuning. I conclude that this series expansion is a natural and useful way to describe the seismic wavelet.

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Hardage, B. A., D. L. Carr, D. E. Lancaster, J. L. Simmons, D. S. Hamilton, R. Y. Elphick, K. L. Oliver, and R. A. Johns. "3-D seismic imaging and seismic attribute analysis of genetic sequences deposited in low‐accommodation conditions." GEOPHYSICS 61, no. 5 (September 1996): 1351–62. http://dx.doi.org/10.1190/1.1444058.

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A multidisciplinary team, composed of stratigraphers, petrophysicists, reservoir engineers, and geophysicists, studied a portion of Boonsville gas field in the Fort Worth Basin of North‐Central Texas to determine how modern geophysical, geological, and engineering techniques could be combined to understand the mechanisms by which fluvio‐deltaic depositional processes create reservoir compartmentalization in a low‐ to moderate‐accommodation basin. An extensive database involving well logs, cores, production, and pressure data from 200‐plus wells, [Formula: see text] [Formula: see text] of 3-D seismic data, vertical seismic profiles (VSPs), and checkshots was assembled to support this investigation. The reservoir system we studied was the Bend Conglomerate, a productive series of gas reservoirs composed of Middle Pennsylvanian fluvio‐deltaic clastics 900 to 1300 ft (275 to 400 m) thick in our project area. We were particularly interested in this reservoir system because evidence suggested that many of the sequences in this stratigraphic interval were deposited in low‐accommodation conditions (that is, in an environment where there was limited vertical space available for sediment accumulation), and our objective was to investigate how fluvio‐deltaic reservoirs were compartmentalized by low‐accommodation depositional processes. Using an extensive well log database (200 plus wells) and a core‐calibrated calculation of rock facies derived from these logs, we divided the Bend Conglomerate interval into ten genetic sequences, with each sequence being approximately 100 ft (30 m) thick. We then used local VSP and checkshot control to transform log‐measured depths of each sequence boundary to seismic two‐way time coordinates and identified narrow seismic data windows encompassing each sequence across the [Formula: see text] [Formula: see text] 3-D seismic grid. A series of seismic attributes was calculated in these carefully defined data windows to determine which attributes were reliable indicators of the presence of productive reservoir facies and which attributes could, therefore, reveal distinct reservoir compartments and potentially show where infield wells should be drilled to reach previously uncontacted gas reservoirs. Our best success was the seismic attribute correlations we found in the Upper and Lower Caddo sequences, at the top of the Bend Conglomerate. These sequences were deposited in a low‐accommodation setting, relative to other Boonsville sequences, and we found that reflection amplitude and instantaneous frequency, respectively, were reliable indicators of the areal distribution of reservoir facies in these low‐accommodation sequences.

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Leopoldino Oliveira, Karen M., Heather Bedle, and Karelia La Marca Molina. "Identification of polygonal faulting from legacy 3D seismic data in vintage Gulf of Mexico data using seismic attributes." Interpretation 9, no. 3 (July 7, 2021): C23—C28. http://dx.doi.org/10.1190/int-2019-0255.1.

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Geological feature: Polygonal faults Seismic appearance: Variable-amplitude plane-parallel horizons without clear discontinuities Features with similar appearance: Seismic noise in stratigraphic sequences without brittle deformation Age: Cenozoic Location: Northern Gulf of Mexico Seismic data: Survey B-01-91-MS obtained by the U.S. National Archive of Marine Seismic Surveys Analysis tools: Geometric seismic attributes

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Maia, Renata Moreira da Costa, Antonio Tadeu dos Reis, Eliane da Costa Alves, Cleverson Guizan Silva, Josefa Varela Guerra, Christian Gorini, Adalberto Silva, and Rodrigo Arantes-Oliveira. "Architecture and stratigraphic framework of shelf sedimentary systems off Rio de Janeiro state, Northern Santos Basin-Brazil." Brazilian Journal of Oceanography 58, spe1 (2010): 15–29. http://dx.doi.org/10.1590/s1679-87592010000500003.

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Seismic analysis of sparker lines of GEOMAR cruises allowed us to address a first stratigraphic scenario for the shallow sedimentary record (~300 msec) of the continental shelf off Rio de Janeiro State, northern Santos basin. Two sets of seismic sequences were identified and interpreted as a succession of depositional sequences induced by repeated glacioeustatic cycles. Depositional sequences composing Set I (SqA-SqC) are dominantly sigmoidal, reflecting periods of increasing accommodation space that favoured the preservation of both aggradational and progradational units; sequences of Set II (Sq1-Sq5) are essentially seaward-thickening stacks of forced-regression wedges, implying periods of declining accommodation space. Comparison between seismic lines and chronostratigraphic data allowed the mapped sequences to be placed within the Plio-Quaternary. Correlations also suggest that most of Set I (SqA and lower portion of SqB) was deposited during the Pliocene (undifferentiated Pliocene), while the upper portion of sequence SqC and sequences of Set II (Sq1-Sq5) have been placed within the Quaternary. Correlation of chronostratigraphic data with δ18O isotopic "sea level curves" also supports the hypothesis that sequences Sq1-Sq4 are fourth-order forced-regression sequences that record 100-120 kyr glacioeustatic cycles for the last 440-500 kyr, while sedimentary units labeled Sq5 would represent the transgressive and highstand deposition during the Holocene.

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Kuchay, O. A. "Aftershocks of the strongest earthquakes in Asia in zones of different seismicity levels." Interexpo GEO-Siberia 2, no. 2 (May 18, 2022): 158–63. http://dx.doi.org/10.33764/2618-981x-2022-2-2-158-163.

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The average values of seismic activity obtained from the aftershock sequences of the strongest earthquakes in Asia (M>6.9) are not correlated with the levels of background seismicity in the areas of the strongest events and their magnitudes. A high level of seismic activity is manifested in zones of large active faults and is reflected in aftershock sequences.

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Liang, Yan, Yukun Cui, and Chao Ren. "Seismic Vulnerability Analysis of Multispan Continuous Bridges Subjected to Mainshock-Aftershock Earthquake Sequences." Advances in Civil Engineering 2020 (June 23, 2020): 1–15. http://dx.doi.org/10.1155/2020/7483850.

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A multispan continuous 3D bridge model is established on the basis of OpenSees platform, and 160 mainshock-aftershock (MA) sequences are constructed in accordance with the bridge site to study their influence on the seismic vulnerability of bridges. The seismic vulnerability of bridge piers, bearings, and abutments subjected to MA sequences is investigated. The influence of MA sequences on the seismic vulnerability of the bridge system is also analysed using first- and second-order boundary estimation methods. Results show that the seismic response and exceedance probability of the bridge components and system subjected to MA sequences are significantly increased compared with those under the consideration of mainshock only. The second-order boundary estimation method based on component correlation coefficient can significantly reduce the upper and lower limit widths of the vulnerability curves and improve the accuracy. Under the same peak ground acceleration (PGA) and damage state, the exceedance probability of the bridge system is higher than that of any component in the system. The exceedance probability under different damage states of the bridge components and system increases with the PGA. For any given PGA, the exceedance probability decreases with the increase in severity of damage state.

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Presti, D. "Probabilistic Location of Seismic Sequences in Heterogeneous Media." Bulletin of the Seismological Society of America 94, no. 6 (December 1, 2004): 2239–53. http://dx.doi.org/10.1785/0120030160.

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D’Amico, Sebastiano, Matteo Cacciola, Francesco Parrillo, Francesco Carlo Morabito, Mario Versaci, and Vincenzo Barrile. "Heuristic advances in identifying aftershocks in seismic sequences." Computers & Geosciences 35, no. 2 (February 2009): 245–54. http://dx.doi.org/10.1016/j.cageo.2008.03.010.

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Telesca, Luciano, Vincenzo Lapenna, Michele Lovallo, and Maria Macchiato. "Long-range time-correlation properties of seismic sequences." Chaos, Solitons & Fractals 21, no. 2 (July 2004): 387–93. http://dx.doi.org/10.1016/j.chaos.2003.12.009.

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Iervolino, Iunio, Eugenio Chioccarelli, and Akiko Suzuki. "Seismic damage accumulation in multiple mainshock–aftershock sequences." Earthquake Engineering & Structural Dynamics 49, no. 10 (April 29, 2020): 1007–27. http://dx.doi.org/10.1002/eqe.3275.

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van der Molen, A. S., and Th E. Wong. "Towards an improved lithostratigraphic subdivision of the Chalk Group in the Netherlands North Sea area - A seismic stratigraphic approach." Netherlands Journal of Geosciences - Geologie en Mijnbouw 86, no. 2 (July 2007): 131–43. http://dx.doi.org/10.1017/s0016774600023131.

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AbstractIn the Netherlands North Sea area, the Chalk Group has thus far been subdivided into the Cenomanian Texel Formation, the Turonian to Maastrichtian Ommelanden Formation and the Danian Ekofisk Formation. This paper describes the attempt to arrive at a more detailed lithostratigraphic subdivision for this area, particularly of the Ommelanden Formation. To this end, a seismic stratigraphic analysis was carried out on a regional 2D and 3D seismic dataset. The Chalk Group was subdivided into eleven seismic stratigraphic sequences, named CK1 through CK11, based on the mapping and correlation of unconformities. The identified seismic sequence boundaries were used as the main chronostratigraphic markers in the Chalk Group interval. The seismic dataset was subsequently expanded with well log data of 45 boreholes. These were tied to the seismic dataset by constructing a synthetic seismogram for each borehole, after which the seismic sequence boundaries were noted and correlated on the logs. Finally, micropaleonthological data available in 15 boreholes were used to date the seismic sequences. The sequences were interpreted to be of Cenomanian (CK1), Turonian (CK2), Coniacian (CK3), Santonian (CK4), Early Campanian (CK5; CK6), Middle to Late Campanian (CK7), Early Maastrichtian (CK8; CK9), Late Maastrichtian (CK10) and Danian (CK11) age. The seismic units recognised in this study were compared with formal lithostratigraphic units defined in the Chalk Group in the surrounding North Sea sectors. Based on this comparison, a revision of the formal lithostratigraphic scheme, recognising Tor Formation and Herring Formation equivalents, is suggested for the Netherlands North Sea area.

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Di, Haibin, Leigh Truelove, Cen Li, and Aria Abubakar. "Accelerating seismic fault and stratigraphy interpretation with deep CNNs: A case study of the Taranaki Basin, New Zealand." Leading Edge 39, no. 10 (October 2020): 727–33. http://dx.doi.org/10.1190/tle39100727.1.

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Accurate mapping of structural faults and stratigraphic sequences is essential to the success of subsurface interpretation, geologic modeling, reservoir characterization, stress history analysis, and resource recovery estimation. In the past decades, manual interpretation assisted by computational tools — i.e., seismic attribute analysis — has been commonly used to deliver the most reliable seismic interpretation. Because of the dramatic increase in seismic data size, the efficiency of this process is challenged. The process has also become overly time-intensive and subject to bias from seismic interpreters. In this study, we implement deep convolutional neural networks (CNNs) for automating the interpretation of faults and stratigraphies on the Opunake-3D seismic data set over the Taranaki Basin of New Zealand. In general, both the fault and stratigraphy interpretation are formulated as problems of image segmentation, and each workflow integrates two deep CNNs. Their specific implementation varies in the following three aspects. First, the fault detection is binary, whereas the stratigraphy interpretation targets multiple classes depending on the sequences of interest to seismic interpreters. Second, while the fault CNN utilizes only the seismic amplitude for its learning, the stratigraphy CNN additionally utilizes the fault probability to serve as a structural constraint on the near-fault zones. Third and more innovatively, for enhancing the lateral consistency and reducing artifacts of machine prediction, the fault workflow incorporates a component of horizontal fault grouping, while the stratigraphy workflow incorporates a component of feature self-learning of a seismic data set. With seven of 765 inlines and 23 of 2233 crosslines manually annotated, which is only about 1% of the available seismic data, the fault and four sequences are well interpreted throughout the entire seismic survey. The results not only match the seismic images, but more importantly they support the graben structure as documented in the Taranaki Basin.

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Giustiniani, Michela, Martina Busetti, Michela Dal Cin, Erika Barison, Aurélie Cimolino, Giuseppe Brancatelli, and Luca Baradello. "Geophysical and Geological Views of Potential Water Resources in the North-Eastern Adriatic Sea." Geosciences 12, no. 3 (March 18, 2022): 139. http://dx.doi.org/10.3390/geosciences12030139.

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The increasing demand for freshwater requires the identification of additional and less-conventional water resources. Amongst these, offshore freshwater systems have been investigated in different parts of the world to provide new opportunities to face increasing water requests. Here we focus on the north-eastern Adriatic Sea, where offshore aquifers could be present as a continuation of onshore ones. Geophysical data, in particular offshore seismic data, and onshore and offshore well data, are interpreted and integrated to characterise the hydrogeological setting via the interpretation of seismo-stratigraphic sequences. We focus our attention on two areas located in the proximity of the Tagliamento and Isonzo deltas. Well and seismic data indicate that the Quaternary sediments, that extend from onshore to offshore areas, are the most promising from an offshore freshwater resources point of view, while the several kilometres thick pre-Quaternary carbonate and terrigenous sequences likely host mainly salty waters.

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Huang, Wei, Jiang Qian, Bin Bin Zhuang, and Qiu Shi Fu. "Damage Assessment of RC Frame Structures under Multi-Earthquake Sequences." Advanced Materials Research 446-449 (January 2012): 739–44. http://dx.doi.org/10.4028/www.scientific.net/amr.446-449.739.

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This paper presents the results of a numerical investigation aimed at evaluation of damage accumulation in structures under different seismic sequences. For this purpose, a multi-story RC frame model representing the typical buildings was built and subjected to four sets of different repeating seismic sequences with different magnitude. The results indicate that the aftershock sequences will increase the damage accumulation in structures, and the damage index based on the Park and Ang model can qualitatively and quantitatively ascertain the damage state of the structure instead of the single index based on the lateral drift demands. Additionally, different sequences with the identical energy input will cause the same damage state in structures.

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Sabu, Berlin, and S. Deepa Balakrishnan. "A Review on the Selection of Real and Artificial Seismic Sequences for Analysis." Proceedings of the 12th Structural Engineering Convention, SEC 2022: Themes 1-2 1, no. 1 (December 19, 2022): 909–13. http://dx.doi.org/10.38208/acp.v1.601.

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A huge mainshock activates several aftershocks, divulging the public to serious risk and impeding building repair, rehabilitation, and restoration works. The performance of a structure during multiple earthquakes depends on structural properties and the characteristics of ground motion. Hence, the selection of seismic sequence plays a vital role in the analysis. Presumption of spatial and temporal characteristics of aftershocks is needed for the identification of these repeated motions. This paper further looks into statistical variability connected with aftershock sequences. A critical review of different real and artificial seismic sequences taken for the analysis is carried out. A few studies reveal that a strong motion database for procuring actual mainshock aftershock sequences could underrate the aftershock effects as the database is inadequate and imperfect. It is also observed that artificial sequences can take the place of real sequences especially when an ample data set of real mainshock aftershock sequences are not accessible.

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Zhu, Chengnan, and Zoltan Hajnal. "Tectonic development of the northern Williston basin: a seismic interpretation of an east – West regional profile." Canadian Journal of Earth Sciences 30, no. 3 (March 1, 1993): 621–30. http://dx.doi.org/10.1139/e93-047.

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Based on seismic analysis in conjunction with well control, 10 time-stratigraphic sequences and sub-sequences are mapped in Phanerozoic strata of the northern Williston basin. Seven additional time-unit subdivisions are distinguished in the upper-most Cretaceous. These sequences, sub-sequences, and units, and their unconformities, reveal that the northern Williston basin experienced three developmental episodes: initial subsidence during the time of deposition of the Sauk sequence (540–505 Ma); stability during the time of deposition of the Tippecanoe to Upper Colorado sequences (480–84 Ma); and deformation since the time of deposition of the Montana sequence (post-66 Ma). The seismic unconformities indicate nine subsidence events separated by five major erosional periods. All the major erosional cycles are consequences of periodic and incongruent uplift and tilting of the western and eastern flanks of the basin relative to its centre.

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Ruiz-García, Jorge, Roberto N. Olvera, and Ariel D. Frías. "Seismic assessment of school buildings with short captive RC columns under subduction seismic sequences." Structures 34 (December 2021): 2432–44. http://dx.doi.org/10.1016/j.istruc.2021.09.019.

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Astiopoulos, A. C., E. Papadimitriou, V. Karakostas, D. Gospodinov, and G. Drakatos. "SEISMICITY CHANGES DETECTION DURING THE SEISMIC SEQUENCES EVOLUTION AS EVIDENCE OF STRESS CHANGES." Bulletin of the Geological Society of Greece 43, no. 4 (January 25, 2017): 1994. http://dx.doi.org/10.12681/bgsg.11390.

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The statistical properties of the aftershock occurrence are among the main issues in investigating the earthquake generation process. Seismicity rate changes during a seismic sequence, which are detected by the application of statistical models, are proved to be precursors of strong events occurring during the seismic excitation. Application of these models provides a tool in assessing the imminent seismic hazard, oftentimes by the estimation of the expected occurrence rate and comparison of the predicted rate with the observed one. The aim of this study is to examine the temporal distribution and especially the occurrence rate variations of aftershocks for two seismic sequences that took place, the first one near Skyros island in 2001 and the second one near Lefkada island in 2003, in order to detect and determine rate changes in connection with the evolution of the seismic activity. Analysis is performed through space–time stochastic models which are developed, based upon both aftershocks clustering studies and specific assumptions. The models applied are the Modified Omori Formula (MOF), the Epidemic Type Aftershock Sequence (ETAS) and the Restricted Epidemic Type Aftershock Sequence (RETAS). The modelling of seismicity rate changes, during the evolution of the particular seismic sequences, is then attempted in association with and as evidence of static stress changes

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Zhang, Hao, Chao Li, Si-Meng Jiang, Peng-Fei Liu, and Qing-Meng Gao. "Fragility Analysis of Concrete-Filled Steel Tubular Frame Structures with BRBs under Multiple Earthquakes Considering Strain Rate Effects." Applied Sciences 10, no. 1 (December 24, 2019): 165. http://dx.doi.org/10.3390/app10010165.

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The fragility of concrete-filled steel tubular (CFST) frame structures with buckling-restrained braces (BRBs) subjected to multiple earthquakes is studied in this paper. First, a fiber beam element model with rate-dependent concrete and steel material properties is developed for CFST members and, then, the effect of the strain rate on the seismic response of the CFST frame structure is investigated numerically. The influence of BRBs on the seismic response of the CFST frame structure is then comparatively analyzed. The seismic responses of the CFST frame structure with BRBs under single mainshocks and earthquake sequences are investigated, and the fragility curves are generated using probabilistic seismic demand analysis. The obtained roof displacement and inter-story drift ratio (ISDR) of the structure decreased by 10.2% and 6.9%, respectively, when obtained while considering the strain rate effect, compared with those obtained without consideration of the strain rate effect. BRBs can effectively improve the seismic performance of the CFST frame structure in that the maximum roof displacement and ISDR can be reduced by 45.1% and 43.9%, respectively. Compared with those under single mainshocks, the maximum roof displacement and ISDR of the structure with BRBs under earthquake sequences significantly increase. The fragility of the BRB structure under earthquake sequences is more severe than that under single mainshocks. Therefore, the influences of the strain rate effect and earthquake sequence should be considered to realistically evaluate the seismic fragility of CFST structures.

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Van Cao, Vui, and Son Quang Pham. "FRP Composite in Mitigating Seismic Risk of RC Structures in Near-Fault Regions with/without Aftershocks." Advances in Civil Engineering 2020 (July 8, 2020): 1–17. http://dx.doi.org/10.1155/2020/2847027.

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The literature related to earthquakes and fibre reinforced polymer (FRP) retrofitting can be divided into two main categories: (1) the applications of FRP to retrofit structures subjected to single traditional earthquakes and (2) the effects of mainshock-aftershock sequences on original structures (without FRP retrofitting). Research on using FRP to mitigate the risk of pulse-type mainshock-aftershock sequences for reinforced concrete (RC) structures located in near-fault regions is hardly found in the literature and is thus the aim of this study. To achieve this aim, a four-storey RC frame, near-fault mainshocks, and seismic sequences were selected. The frame was retrofitted using FRP wraps at plastic hinge locations. Nonlinear time history and damage analyses of the original and FRP-retrofitted frames subjected to these near-fault mainshocks and seismic sequences were conducted. The results showed that aftershocks significantly increase the damage indices of the frames, shifting the damage state of the original frame from severe damage to collapse and the damage state of the FRP-retrofitted frame from light damage to moderate damage. FRP retrofitting successfully reduced the risk of seismic sequences by reducing the damage two levels, shifting the damage state of the original frame from collapse to moderate damage.

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ALIOTTA, SALVADOR, SILVIA S. GINSBERG, DARÍO GIAGANTE, LAURA G. VECCHI, and MARTA M. SALVATIERRA. "Seismic Stratigraphy of Pleistocene Deltaic Deposits in Bahía Blanca Estuary, Argentina." Anais da Academia Brasileira de Ciências 86, no. 2 (June 2014): 649–62. http://dx.doi.org/10.1590/0001-3765201420130243.

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The Bahía Blanca estuary (Argentina) has a morphological configuration resulting from hydrological and sedimentary processes related to Late Quaternary sea level changes. This estuarine system occupies a large coastal plain with a dense net of tidal channels, low-altitude islands and large intertidal flats. Little is known about the sedimentary units of the marine subbottom. Therefore, a stratigraphical analysis of the northern coast of Bahía Blanca estuary was carried out using high resolution seismic (3.5 kHz) in order to: i) define Quaternary sequences, ii) describe sedimentary structures, and iii) determine the paleoenvironmental conditions of sedimentation. The seismic stratigraphic data collected and their correlation with drilling lithological data show five seismic sequences (S1, S2, S3, S4 and S5), of which S1-S2 were found to be associated with a continental paleoenvironment of Miocene-Pleistocene age. Sequences S3 and S4, whose lithology and seismic facies (paleochannel structures and prograding reflection configurations), were defined on these materials, to evidence the development of an ancient deltaic environment which was part of a large Pleistocene drainage system. The S5 sequence was formed during the Holocene transgressive-regressive process and complete the seismostratigraphic column defined in the present study.

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Konstandakopoulou, Foteini, Maria Konstantinidou, Nikos Pnevmatikos, and George D. Hatzigeorgiou. "Safety and Performance of Offshore Platforms Subjected to Repeated Earthquakes." Infrastructures 5, no. 4 (April 22, 2020): 38. http://dx.doi.org/10.3390/infrastructures5040038.

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In this work, a systematic study is conducted on the behavior of three-dimensional offshore oil/natural gas platforms under the action of seismic sequences. Such repeated earthquakes result in a noteworthy accumulation of damage in a platform since, in many cases, any rehabilitation process between any two or more successive ground motions cannot be essentially materialized because of lack of time. Conversely, in the past, the seismic response of offshore platforms has been exclusively investigated for the case of single earthquakes. In this study, two three-dimensional platforms are examined, where the first one is assumed to be completely constrained at its base (fixed boundary conditions), while the second one is founded in deformable soil with the aid of long piles. These structures are subjected to real seismic sequences which have been recorded by the same station in a short period of time. Additionally, the platforms under consideration are also subjected to artificial seismic sequences. In this study, we found that sequential earthquakes have a significant effect on the response of these special structures, and this finding should be taken into account in their design.

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Quinones, Louis, Heather R. DeShon, SeongJu Jeong, Paul Ogwari, Oner Sufri, Monique M. Holt, and Kevin B. Kwong. "Tracking Induced Seismicity in the Fort Worth Basin: A Summary of the 2008–2018 North Texas Earthquake Study Catalog." Bulletin of the Seismological Society of America 109, no. 4 (June 11, 2019): 1203–16. http://dx.doi.org/10.1785/0120190057.

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Abstract Since 2008, earthquake sequences within the Fort Worth basin (FWB), north Texas, have been linked to wastewater disposal activities related to unconventional shale‐gas production. The North Texas Earthquake Study (NTXES) catalog (2008–2018), described and included herein, uses a combination of local and regional seismic networks to track significant seismic sequences in the basin. The FWB earthquakes occur along discrete faults that are relatively far apart (>30 km), allowing for more detailed study of individual sequence development. The three largest sequences (magnitude 3.6+) are monitored by local seismic networks (<15 km epicentral distances), whereas basinwide seismicity outside these three sequences is monitored using regional distance stations. A regional 1D velocity model for the FWB reflects basinwide well log, receiver function, and regional crustal structure studies and is modified for the larger individual earthquake sequences using local well‐log and geology data. Here, we present an mb_Lg relationship appropriate for Texas and a basin‐specific ML relationship, both calculated using attenuation curves developed with the NTXES catalog. Analysis of the catalog reveals that the earthquakes generally occur within the Precambrian basement formation along steeply dipping normal faults, and although overall seismicity rates have decreased since 2016, new faults have become active. Between 2006 and 2018, more than 2 billion barrels of fluids were injected into the Ellenburger formation within the FWB. We observe strong spatial and temporal correlations between the earthquake locations and wastewater disposal well locations and injection volumes, implying that fluid injection activities may be the main driving force of seismicity in the basin. In addition, we observe seismicity occurring at greater distances from injection wells (>10 km) over time, implying that far‐field stress changes associated with fluid injection activities may be an important component to understanding the seismic hazard of induced seismicity sequences.

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Cadena, Andrea F., and Roger M. Slatt. "Seismic and sequence stratigraphic interpretation of the area of influence of the Magdalena submarine fan, offshore northern Colombia." Interpretation 1, no. 1 (August 1, 2013): SA53—SA74. http://dx.doi.org/10.1190/int-2013-0028.1.

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The area of influence of the Magdalena submarine fan, offshore northern Colombia, is a global frontier basin with sparse well control and only publically available 2D seismic from which to conduct exploration surveys. We have conducted a 2D seismic stratigraphic study to advance knowledge of the tectonostratigraphic evolution of this area and, furthermore, optimize exploration concepts to include stratigraphy and sedimentology to enhance such opportunities. Eight third-order seismic sequences from the early Miocene to Holocene comprise the stratigraphic record. Seismic character, thickness, and sedimentary processes vary in each sequence based on the area of deposition. Three geomorphologic areas are subject to deposition: the Tayrona depression, the undeformed central Magdalena fan and deformed wedges on either side of the fan. From oldest to youngest, sequences I to V represent bathyal paleo-environments that were deformed during the late Miocene Andean phase. Deformation of these sequences is thin skinned thrust sheets, where the main basal detachment corresponds to Oligocene shale. This deformation continued until the middle Pliocene, when sequence VI and VII were deposited on the Magdalena Fan mainly as mass transport and channel-levee deposits. Sequence VIII represents the record from early Pleistocene to the present time. From early Pliocene to present, erosion was mainly the product of submarine fan activity and bypass in areas of high slope, whereas for older deposits, erosion was caused by exposure to subaerial conditions. Superimposed on the third-order sequences are fourth-order sequences, which reveal a relative (tectonic-eustatic) sea level increase from Early Miocene to middle Late Miocene (Tortonian) time, followed by a lowstand event that extended until Holocene time. Potential reservoirs embedded within the sequences include sheet sands, channel fills, and levee-overbank. Other components of the petroleum system such as a mature source rock are still under debate.

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Journal articles on the topic 'Seismic sequences'

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