Journal articles on the topic 'Seismic zones classifications'
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1
Petersen, Mark D., Tousson R. Toppozada, Tianqing Cao, Chris H. Cramer, Michael S. Reichle, and William A. Bryant. "Active Fault Near-Source Zones within and Bordering the State of California for the 1997 Uniform Building Code." Earthquake Spectra 16, no. 1 (February 2000): 69–83. http://dx.doi.org/10.1193/1.1586083.
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The fault sources in the Project 97 probabilistic seismic hazard maps for the state of California were used to construct maps for defining near-source seismic coefficients, Na and Nv, incorporated in the 1997 Uniform Building Code (ICBO 1997). The near-source factors are based on the distance from a known active fault that is classified as either Type A or Type B. To determine the near-source factor, four pieces of geologic information are required: (1) recognizing a fault and determining whether or not the fault has been active during the Holocene, (2) identifying the location of the fault at or beneath the ground surface, (3) estimating the slip rate of the fault, and (4) estimating the maximum earthquake magnitude for each fault segment. This paper describes the information used to produce the fault classifications and distances.
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Lehocki, Ivan, Per Avseth, and Nazmul Haque Mondol. "Seismic methods for fluid discrimination in areas with complex geologic history — A case example from the Barents Sea." Interpretation 8, no. 1 (February 1, 2020): SA35—SA47. http://dx.doi.org/10.1190/int-2019-0057.1.
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We have developed a new scheme for calculation of density ratio, an attribute that can be directly linked to hydrocarbon saturation, and applied it to seismic amplitude variation with offset (AVO) data from the Hoop area in the Barents Sea. The approach is based on the inversion of Zoeppritz’s equation for PP-wave. Furthermore, by using interval velocities, we quantified uplift magnitude for a given interval beneath Base Cretaceous unconformity (BCU) horizon in the Hoop area. Depending on the temperature gradient, the maximum burial depth can be estimated, a crucial factor affecting the elastic properties of the rocks. Coupling uplift map with temperature history for key stratigraphic units from basin modeling enabled us to extend the training data away from well control. By doing so, we created nonstationary AVO probability density functions (PDFs) for calibration and classification of seismic attributes in the test area. This decreases the likelihood of misclassification of pore fluid type as opposed to the case where the training data are created based only on sparse well-log data. We tested and compared the methods on the Barents Sea seismic data set, and the results were validated at four well locations. Finally, maps of fluid distribution obtained from stochastic rock-physics modeling honoring burial history were compared against the density ratio map. Four maps revealed the same anomalous zones, the major difference being the detection of the down-flank presence of oil associated with some of the predicted gas anomalies in the prospect area, in the case of density ratio map. Possible gas caps were detected/predicted only for certain temperature constraints during the AVO classifications and were most obvious in the density ratio map.
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Jesus, Carlos, Maria Olho Azul, Wagner Moreira Lupinacci, and Leandro Machado. "Multiattribute framework analysis for the identification of carbonate mounds in the Brazilian presalt zone." Interpretation 7, no. 2 (May 1, 2019): T467—T476. http://dx.doi.org/10.1190/int-2018-0004.1.
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Carbonate mounds, as described herein, often present seismic characteristics such as low amplitude and a high density of faults and fractures, which can easily be oversampled and blur other rock features in simple geobody extraction processes. We have developed a workflow for combining geometric attributes and hybrid spectral decomposition (HSD) to efficiently identify good-quality reservoirs in carbonate mounds within the complex environment of the Brazilian presalt zone. To better identify these reservoirs within the seismic volume of carbonate mounds, we divide our methodology into four stages: seismic data acquisition and processing overview, preconditioning of seismic data using structural-oriented filtering and imaging enhancement, calculation of seismic attributes, and classification of seismic facies. Although coherence and curvature attributes are often used to identify high-density fault and fracture zones, representing one of the most important features of carbonate mounds, HSD is necessary to discriminate low-amplitude carbonate mounds (good reservoir quality) from low-amplitude clay zones (nonreservoir). Finally, we use a multiattribute facies classification to generate a geologically significant outcome and to guide a final geobody extraction that is calibrated by well data and that can be used as a spatial indicator of the distribution of good reservoir quality for static modeling.
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Polom, U., I. Arsyad, and H. J. Kümpel. "Shallow shear-wave reflection seismics in the tsunami struck Krueng Aceh River Basin, Sumatra." Advances in Geosciences 14 (January 2, 2008): 135–40. http://dx.doi.org/10.5194/adgeo-14-135-2008.
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Abstract. As part of the project "Management of Georisk" (MANGEONAD) of the Federal Institute for Geosciences and Natural Resources (BGR), Hanover, high resolution shallow shear-wave reflection seismics was applied in the Indonesian province Nanggroe Aceh Darussalam, North Sumatra in cooperation with the Government of Indonesia, local counterparts, and the Leibniz Institute for Applied Geosciences, Hanover. The investigations were expected to support classification of earthquake site effects for the reconstruction of buildings and infrastructure as well as for groundwater exploration. The study focussed on the city of Banda Aceh and the surroundings of Aceh Besar. The shear-wave seismic surveys were done parallel to standard geoengineering investigations like cone penetrometer tests to support subsequent site specific statistical calibration. They were also partly supplemented by shallow p-wave seismics for the identification of (a) elastic subsurface parameters and (b) zones with abundance of groundwater. Evaluation of seismic site effects based on shallow reflection seismics has in fact been found to be a highly useful method in Aceh province. In particular, use of a vibratory seismic source was essential for successful application of shear-wave seismics in the city of Banda Aceh and in areas with compacted ground like on farm tracks in the surroundings, presenting mostly agricultural land use areas. We thus were able to explore the mechanical stiffness of the subsurface down to 100 m depth, occasionally even deeper, with remarkably high resolution. The results were transferred into geotechnical site classification in terms of the International Building Code (IBC, 2003). The seismic images give also insights into the history of the basin sedimentation processes of the Krueng Aceh River delta, which is relevant for the exploration of new areas for construction of safe foundations of buildings and for identification of fresh water aquifers in the tsunami flooded region.
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O. Oshogbunu, Fredrick, and Pius A. Enikanselu. "Machine learning approach to hydrocarbon zone prediction from seismic attributes over “GEM” field, Niger-Delta, Nigeria." International Journal of Advanced Geosciences 9, no. 2 (November 19, 2021): 88. http://dx.doi.org/10.14419/ijag.v9i2.31811.
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A computer programme (in Python language) was developed for the generation and performance assessment of predictive models, capable of combining relevant seismic attributes for reliable hydrocarbon zone prediction ahead of drilling. It attempts to resolve the problem of making accurate and efficient interpretations from a large database of derived seismic attributes. The research utilized post-stack 3D seismic volume for the delineation of structures and the generation of seismic attributes. Six faults were identified across the mapped horizons. Five seismic attributes were generated and exported from 3D seismic data as numerical values for machine learning analysis. The binary cross-entropy classification metric was used to evaluate the performance of the developed predictive models while an individual seismic attribute (Maximum Amplitude and Extract value) map was used to validate the predictive models. A correlation of well depth-to-top of selected horizons with the seismic depth slice surface was used for further model validation. The Multi-Layer Perceptron (MLP) model results enhanced the visibility of the other five hydrocarbon prediction zones. The MLP predictive model map gave higher precision of the predicted hydrocarbon zones over the Self-Organising Map (SOM) predictive model, thus reinforcing the confidence level of the former.
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Ialalov, D. M., M. V. Romashov, I. V. Oreshko, I. P. Vorontsov, and A. E. Ibraev. "Revising geological model for north flank of main production interval in oil field." Kazakhstan journal for oil & gas industry 2, no. 2 (June 15, 2020): 14–20. http://dx.doi.org/10.54859/kjogi95617.
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Based on the results of the previous works performed at the studied oil field, a significant potential for increasing initial oil reserves was established. Three wells were drilled in the edge zone of the field at the end of 2019, which confirmed the potential in the undrilled area of the northern flank of the filed. Until these wells were drilled, the edge zone was considered unpromising.The authors have been tasked to assess perspectives of development of edge zones and build a detailed geological model for that area. The detailed model is intended to forecast the evolution of elements of the fluvial system for based on drilling data and results of seismic researches in undrilled parts of field.In order to forecast the distribution zones of channel complexes, high-resolution 3D seismic data of 2019 were used. Based on the dynamic analysis, interpretation of the distribution zones of channel complexes and their classification within the studied reservoir layer were performed. The main focus was on identifying and mapping of small channels in the boundary zone of the reservoir with the aim of further detailed geological modeling and assessment of the development potential, taking into account new data.
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Koutsoupakis, Ioannis, Yiannis Tsompanakis, Pantelis Soupios, Panagiotis Kirmizakis, SanLinn Kaka, and Costas Providakis. "Seismic Risk Assessment of Chania, Greece, Using an Integrated Computational Approach." Applied Sciences 11, no. 23 (November 26, 2021): 11249. http://dx.doi.org/10.3390/app112311249.
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This study develops a comprehensive seismic risk model for the city of Chania, in Greece, which is located ina highly seismic-prone region due to the occurrenceof moderate to large earthquakes because of the nearby major subduction zone between African and Eurasian tectonic plates. The main aim is to reduce the seismic risk for the study area by incorporating the spatial distribution of the near-surface shear wave velocity model and the soil classification, along with all possible seismic sources, taking into account historical events. The study incorporates and correlates various ground motion scenarios and geological fault zones as well as information on existing buildings to develop a seismic risk model using QuakeIST software, and then the seismic hazard and a realistic prediction of resulting future adverse effects are assessed. The developed model can assist the municipal authorities of Chania to be prepared for potential seismic events, as well as city planners and decisionmakers, who can use the model as an effective decision-making tool to identify the seismic vulnerability of the city buildings and infrastructure. Thus, this study enables the implementation of an appropriate and viable earthquake-related hazards strategy to mitigate damage and losses in future earthquakes.
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Brescia, Manuela. "Rotation capacity and steel members classification criteria in seismic zones." Pollack Periodica 2, no. 2 (August 2007): 63–73. http://dx.doi.org/10.1556/pollack.2.2007.2.6.
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Decanini, Luis, Giacomo Di Pasquale, Paolo Galli, Fabrizio Mollaioli, and Tito Sanò. "Seismic Hazard and Seismic Zonation of the Region Affected by the 2002 Molise, Italy, Earthquake." Earthquake Spectra 20, no. 1_suppl (July 2004): 131–65. http://dx.doi.org/10.1193/1.1771012.
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In 1998, a new system of seismic classification promoted by the Department of Civil Protection identified the area in Italy hit by the 2002 earthquake in Molise and Puglia as a Zone 2 (moderately seismic). However, this classification was not adopted until March 2003, when an ordinance passed that partially closed the gap between scientific knowledge and official recognition of seismic hazard and that established a method for constantly updating the classification in the future. This paper reviews some of the methods available to assess the seismic hazard, particularly referring to the rich seismic history of Italy and using the “Associated Seismic Area” concept. This study confirms that the area affected by this earthquake should be considered as Zone 2. An appendix presents data on the seismic risk of existing buildings in the area and concludes that it is high for masonry buildings and that a strengthening program is needed.
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Del Gaudio, V., P. Pierri, and G. Calcagnile. "Seismogenic zonation and seismic hazard estimates in a Southern Italy area (Northern Apulia) characterised by moderate seismicity rates." Natural Hazards and Earth System Sciences 9, no. 1 (February 17, 2009): 161–74. http://dx.doi.org/10.5194/nhess-9-161-2009.
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Abstract. The northernmost part of Apulia, in Southern Italy, is an emerged portion of the Adriatic plate, which in past centuries was hit by at least three disastrous earthquakes and at present is occasionally affected by seismic events of moderate energy. In the latest seismic hazard assessment carried out in Italy at national scale, the adopted seismogenic zonation (named ZS9) has defined for this area a single zone including parts of different structural units (chain, foredeep, foreland). However significant seismic behaviour differences were revealed among them by our recent studies and, therefore, we re-evaluated local seismic hazard by adopting a zonation, named ZNA, modifying the ZS9 to separate areas of Northern Apulia belonging to different structural domains. To overcome the problem of the limited datasets of historical events available for small zones having a relatively low rate of earthquake recurrence, an approach was adopted that integrates historical and instrumental event data. The latter were declustered with a procedure specifically devised to process datasets of low to moderate magnitude shocks. Seismicity rates were then calculated following alternative procedural choices, according to a "logic tree" approach, to explore the influence of epistemic uncertainties on the final results and to evaluate, among these, the importance of the uncertainty in seismogenic zonation. The comparison between the results obtained using zonations ZNA and ZS9 confirms the well known "spreading effect" that the use of larger seismogenic zones has on hazard estimates. This effect can locally determine underestimates or overestimates by amounts that make necessary a careful reconsideration of seismic classification and building code application.
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Imaeva, Lyudmila P., Valery S. Imaev, and Boris M. Koz’min. "Dynamics of the Zones of Strong Earthquake Epicenters in the Arctic–Asian Seismic Belt." Geosciences 9, no. 4 (April 12, 2019): 168. http://dx.doi.org/10.3390/geosciences9040168.
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Our comprehensive study of the Russian Arctic region aims to clarify the features and types of seismotectonic deformation of the crust in the Arctic–Asian Seismic Belt, specifically in the zones of strong earthquakes in the Laptev Sea Segment, the Kharaulakh Segment, and the Chersky Seismotectonic Zone. We have analyzed modern tectonic structures and active fault systems, as well as tectonic stress fields reconstructed by tectonophysical analysis of the Late Cenozoic faults and folds. The investigated neotectonic structures are ranked with respect to the regional classification principles. Changes in the crustal stress–strain state in the lithospheric plate boundaries between the Eurasian, North American, and Okhotsk Sea Plates are analyzed, and regularities of such changes are discovered. A set of models has been constructed for the studied segments of plate boundaries with account of the dynamics of the regional geological structures. The models can give a framework for the assessment of potential seismic risks of seismogenerating structures in the Russian Arctic region.
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Mattos-Rodriguez, Adriana, Stevens Barraza, and Camilo Verbel Almario. "Comparison of seismic provisions of Andean countries." International Journal of Engineering & Technology 9, no. 4 (November 10, 2020): 871. http://dx.doi.org/10.14419/ijet.v9i4.31219.
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This paper presents a seismic provisions comparison used in the countries of the Andean region. A brief summary of the Andean region seismicity, showing historical seismicity and the probability of earthquake occurrence in each Andean country and the overall zone is pre-sented; then a seismic provisions comparison is presented in tables taking into account the seismic hazard according to the peak ground acceleration, the site effects according to the soil classification and response spectra pseudo-acceleration. Finally, a static analysis of seismic force is carried out for each country in an intermediate-to-high seismic zone, the base design shear force is computed, and the results are compared.
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Li, Cheng Cheng, and Xiao Ming Yuan. "Analysis of the Potential of Seismic Stability for the Southern Region of Tangshan Based on ArcGIS." Advanced Materials Research 919-921 (April 2014): 915–20. http://dx.doi.org/10.4028/www.scientific.net/amr.919-921.915.
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To assess the potential of seismic stability for the southern region of Tangshan city, five factors are considered, including fault zones, engineering geological condition, hydrogeology condition, dynamic coefficient and site category. In this paper, the process and digitalization and visualization technology of evaluation method for site seismic stability is proposed based on ArcGIS. The overlay method is automatic realized and the seismic stability potential diagram of Tangshan and its southern region is given, which overcomes the drawback that can't automatic classification of other GIS instruments, then time is greatly saved and the efficiency is improved.
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Meng, Hua Jun, and Jian Ping Qiao. "The Spatial Distribution Characteristics of Seismic Induced Geo-Hazards and Ground Damage Classification in Baisha River." Advanced Materials Research 594-597 (November 2012): 1727–33. http://dx.doi.org/10.4028/www.scientific.net/amr.594-597.1727.
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The Baisha river basin was extremely destroyed by the Wenchuan earthquake. This paper extracted the seismic-induced geological disasters data about 26km2 within an area of 368.25km2 by remote sensing interpretation and field investigation. This paper used arcgis to analysis these data, and divided the basin into several belts or zones base on slope, aspect, elevation and stratum lithology. The geo-hazard distribution analysis model was built to find some correlation between disaster distribution and geological factors such as terrain, stratum lithology and geomorphology by comparing among the parameters Ps, Ph, and Pc. The results show that most hazards occur where the slope between 30° and 50°, or aspect range is112.5° to 202.5°, and or the elevation between1140m and 3140m, the stratum lithology are the Huangshuihe group and The Middle Proterozoic common granite. At last the research zone is classified into four levels base on ground destroyed grade, and results show that the belts of most hazards located are not always the one destroyed most heavily.
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Zhiquan, Ding, Wang Zhizhao, and Li Bo. "General Comparison of Seismic Design between the Chinese Code and the European code." E3S Web of Conferences 276 (2021): 01031. http://dx.doi.org/10.1051/e3sconf/202127601031.
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To promote overseas projects, it is necessary for designers to understand and distinguish the similarities and differences between the Chinese standard GB50011(Edition 2016) and the European standard EN1998. By referring to relevant papers, comparing the ground types, response spectrum, structural importance factors, seismic precaution level and seismic zoning between the GB50011(Edition 2016) and EN1998, it can be concluded that the overall seismic design concepts in the Chinese and European codes are similar but there are some small differences in ground type classification, impact of ground type on seismic action, response spectrum, importance factor, seismic precautionary criterion, seismic precautionary measures, and seismic zone.
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Zuenko, A. A., O. V. Fridman, O. G. Zhuravleva, and S. A. Zhukova. "Methods of group classification based on the theory of multisets in the problem of localizing zones with different levels of seismic activity during mining." Transaction Kola Science Centre 11, no. 8-2020 (December 16, 2020): 26–38. http://dx.doi.org/10.37614/2307-5252.2020.8.11.002.
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The work is dedicated to assessing the applicability of supervised group classification methods developed on the basis of multiset theory for solving the problem of identifying zones with different degrees of seismic activity (using the example of one of the sections of the highly stressed rock massif of the Kukisvumchorr apatite-nepheline deposit). The initial objects for classification procedures are spatial cells into which the fieldis divided. Each spatial cell is described by a certain set of factors that, according to experts, have an impact on the occurrence of seismic events in a given cell. An original representation of spatial cells (their groups) as a set of multisets is proposed. Studies have been carried out aimed at identifying the influence of various options for presenting the initial data on the result of classification procedures. Representation of objects described by quantitative and / or qualitative features and existing in several versions (copies) in the form of multisets makes it possible not to transform qualitative features into numerical ones when performing clustering procedures and use methods of group classification of objects. Generalized decision rules of group classification for assigning objects (spatial cells) to four classes of seismic hazard are obtained. In contrast to the currently widely used technologies based on the neural network approach, in this work, the training result is not a “black box” in the form of a trained neural network, but a set of rules that can be easily interpreted, which increases the confidence of end users in decision-making procedures.
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Zhang, Bang Hua, and Hong Shui Tian. "Analyzing Seismic Destructive Effect to the Submarine Rock and Soil Layers According to Submarine Seismic Records." Applied Mechanics and Materials 166-169 (May 2012): 2494–506. http://dx.doi.org/10.4028/www.scientific.net/amm.166-169.2494.
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By means of survey and study, various submarine seismic records were identified in the marine facies strata from Sinian Period to Ordovician Period in Tancheng-Lujiang seismic fault zone and its vicinity. These submarine seismic records are divided into two classes. According to the mode of seismic action, every class of submarine seismic records is divided into three to four types. On the basis of classification, this paper studied and summarized seismic destructive effects to the submarine rock and soil layers and diagrammatized mechanism and process of seismic destructive effects. Seismic destructive effects to soft sedimentary soil strata mainly include seismic vibratory liquefaction, vibratory thixotropic effect, seismic fold deformation, sliding deformation, tensile deformation and combined action of shaking and weight. Seismic destructive effects to submarine soil strata of semi-consolidated to un-completely consolidated sediments mainly include syn-sedimentary fault effect, crack and smashing effect, filling effect of seismic crack, etc.
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Weidman, Luke, Jillian M. Maloney, and Thomas K. Rockwell. "Geotechnical data synthesis for GIS-based analysis of fault zone geometry and hazard in an urban environment." Geosphere 15, no. 6 (October 16, 2019): 1999–2017. http://dx.doi.org/10.1130/ges02098.1.
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Abstract Many fault zones trend through developed urban areas where their geomorphic expression is unclear, making it difficult to study fault zone details and assess seismic hazard. One example is the Holocene-active Rose Canyon fault zone, a strike-slip fault with potential to produce a M6.9 earthquake, which traverses the city of San Diego, California (USA). Several strands trend through densely populated areas, including downtown. Much of the developed environment in San Diego predates aerial imagery, making assessment of the natural landscape difficult. To comply with regulations on development in a seismically active area, geotechnical firms have conducted many private, small-scale fault studies in downtown San Diego since the 1980s. However, each report is site specific with minimal integration between neighboring sites, and there exists no resource where all data can be viewed simultaneously on a regional scale. Here, geotechnical data were mined from 268 individual reports and synthesized into an interactive geodatabase to elucidate fault geometry through downtown San Diego. In the geodatabase, fault segments were assigned a hazard classification, and their strike and dip characterized. Results show an active zone of discontinuous fault segments trending north-south in eastern downtown, including active faults outside the mapped regulatory Earthquake Fault Zone. Analysis of fault geometry shows high variability along strike that may be associated with a stepover into San Diego Bay. This type of geodatabase offers a method for compiling and analyzing a high volume of small-scale fault investigations for a more comprehensive understanding of fault zones located in developed regions.
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Méndez, José N., Qiang Jin, María González, Wei Hehua, and Cyril D. Boateng. "Predicting and 3D modeling of karst zones using seismic facies analysis in Ordovician carbonates of the Tahe oilfield, China." Interpretation 8, no. 2 (May 1, 2020): T293—T307. http://dx.doi.org/10.1190/int-2019-0090.1.
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Karsted carbonates of the Ordovician Yingshan Formation represent significant hydrocarbon reservoirs in the Tarim Basin, China. Due to the geologic complexity of the formation, realistically predicting and modeling karst zones and rock properties is challenging. This drives the need to apply diverse techniques for building a suitable geologic model. We have developed a static model approach that uses fully automated seismic facies classification processes for predicting and modeling patterns associated with karst elements. Our method uses a seismic attribute and well logs as input data. We initially processed a seismic facies volume using the hierarchical clustering technique. This is based on seismic attribute values that take into account an optimal number of classes. The outcome reveals various patterns illustrated with low amplitudes highlighting the geomorphology of paleokarst elements. Simultaneously, a seismic traces map of the karsted interval was processed using the hybrid clustering technique conducted on seismic trace shape. In this case, the karst facies was extracted from the output and used as secondary input data in trend analysis of the model. Both outputs obtained from clustering techniques are processed in a volume of the most probable facies, which delineate the karst patterns. The results of the modeling process are visualized in various time slices and cross sections, appropriately recognizing the relationship of estimated patterns with karst zones. We have evaluated the karstification thickness and porosity map obtained from the 3D model that detail a reasonable connectivity between karst elements. This is based on the paleogeographic location and type of filling, as well as the dissolution development along the main striking faults. Finally, our method outputs a logical model of karst zones located within the host rock, which reduces the uncertainty and identify nonperforated segments.
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Pilecki, Zenon. "Geophysical identification of voids and loosened zones in the shallow subsurface of post-mining areas." E3S Web of Conferences 66 (2018): 01001. http://dx.doi.org/10.1051/e3sconf/20186601001.
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The shallow historic exploitation of Zn-Pb/Fe ore deposits as well as hard coal has generated many discontinuous deformations on the terrain surface in the Upper Silesian Coal Basin/Poland. Discontinuous deformations occur in different forms as sinkholes, synclines, cracks, faults or ditches. The basic cause of their occurrence is the presence of void and loosened zones in the shallow subsurface. If the appropriate conditions arise, the sinkhole process begins to move upwards and may cause a discontinuous deformation on the terrain surface. Typically, geophysical methods are used for void and loosened zone identification. The most effective methods are gravimetric, seismic, electric resistivity and ground penetrating radar (GPR). Geophysical testing, requires distinct changes in the physical properties in the rock mass. The identified geophysical anomalies should be verified by control borehole and borehole tests to confirm the presence of the void and loosened zones in the rock mass. The results of control drilling and borehole tests determine the need to apply treatment works. In order to assess the threat of the occurrence of discontinuous deformations in the areas of historical shallow mining in Upper Silesia, a classification system based on geophysical tests has also been developed.
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Parammal Vatteri, Ahsana, and Dina D’Ayala. "Classification and seismic fragility assessment of confined masonry school buildings." Bulletin of Earthquake Engineering 19, no. 5 (March 2021): 2213–63. http://dx.doi.org/10.1007/s10518-021-01061-9.
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AbstractSchool buildings being a critical social infrastructure, assessment of their seismic behaviour is of utmost importance in ensuring safe schooling facilities in locations of high seismicity. This study presents two important aspects in analysing any existing building stock for seismic behaviour: the development of an appropriate taxonomy system and an appropriate analytical method to conduct fragility assessment. A detailed desk study of existing schools’ databases and tailored field investigation in Guwahati, Assam, situated in India’s highest seismic zone, reveal that the majority of school buildings can be categorised within the confined masonry (CM) typology. This study discusses first, the addition to the World Bank promoted Global Library of School Infrastructure taxonomy of the specific category relating to CM as to include the buildings under study, which are non-engineered CM buildings with flexible roofs. Identifying the density of confinement and quality of connections as critical parameters for the seismic response of these buildings, varying seismic design levels are defined in relation to these indicators. Secondly, the paper presents an approach for carrying out nonlinear static pushover analysis of these buildings with flexible diaphragms and elaborates on the criteria adopted for determining the performance drift limits in buildings with varying levels of seismic design. Numerical analysis for the capacity assessment of selected index buildings is carried out using a commercial software that enables nonlinear extreme loading analysis. Different failure mechanisms as a function of the level of confinement are identified and the performance range for three damage states for three index buildings is obtained by using the N2 method. The study shows the influence of both choices of performance indicators and intensity measure on the resulting fragility functions. Given the consistency of the educational building stock in Guwahati, the results can be used for investment on retrofit decision making at regional level.
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Alizadeh, Mohsen, Hasan Zabihi, Fatemeh Rezaie, Asad Asadzadeh, Isabelle D. Wolf, Philip K. Langat, Iman Khosravi, Amin Beiranvand Pour, Milad Mohammad Nataj, and Biswajeet Pradhan. "Earthquake Vulnerability Assessment for Urban Areas Using an ANN and Hybrid SWOT-QSPM Model." Remote Sensing 13, no. 22 (November 10, 2021): 4519. http://dx.doi.org/10.3390/rs13224519.
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Tabriz city in NW Iran is a seismic-prone province with recurring devastating earthquakes that have resulted in heavy casualties and damages. This research developed a new computational framework to investigate four main dimensions of vulnerability (environmental, social, economic and physical). An Artificial Neural Network (ANN) Model and a SWOT-Quantitative Strategic Planning Matrix (QSPM) were applied. Firstly, a literature review was performed to explore indicators with significant impact on aforementioned dimensions of vulnerability to earthquakes. Next, the twenty identified indicators were analyzed in ArcGIS, a geographic information system (GIS) software, to map earthquake vulnerability. After classification and reclassification of the layers, standardized maps were presented as input to a Multilayer Perceptron (MLP) and Self-Organizing Map (SOM) neural network. The resulting Earthquake Vulnerability Maps (EVMs) showed five categories of vulnerability ranging from very high, to high, moderate, low and very low. Accordingly, out of the nine municipality zones in Tabriz city, Zone one was rated as the most vulnerable to earthquakes while Zone seven was rated as the least vulnerable. Vulnerability to earthquakes of residential buildings was also identified. To validate the results data were compared between a Multilayer Perceptron (MLP) and a Self-Organizing Map (SOM). The scatter plots showed strong correlations between the vulnerability ratings of the different zones achieved by the SOM and MLP. Finally, the hybrid SWOT-QSPM paradigm was proposed to identify and evaluate strategies for hazard mitigation of the most vulnerable zone. For hazard mitigation in this zone we recommend to diligently account for environmental phenomena in designing and locating of sites. The findings are useful for decision makers and government authorities to reconsider current natural disaster management strategies.
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Kim, Han-Saem, Chang-Guk Sun, and Hyung-Ik Cho. "Geospatial Assessment of the Post-Earthquake Hazard of the 2017 Pohang Earthquake Considering Seismic Site Effects." ISPRS International Journal of Geo-Information 7, no. 9 (September 10, 2018): 375. http://dx.doi.org/10.3390/ijgi7090375.
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The 2017 Pohang earthquake (moment magnitude scale: 5.4) was South Korea’s second strongest earthquake in decades, and caused the maximum amount of damage in terms of infrastructure and human injuries. As the epicenters were located in regions with Quaternary sediments, which involve distributions of thick fill and alluvial geo-layers, the induced damages were more severe owing to seismic amplification and liquefaction. Thus, to identify the influence of site-specific seismic effects, a post-earthquake survey framework for rapid earthquake damage estimation, correlated with seismic site effects, was proposed and applied in the region of the Pohang earthquake epicenter. Seismic zones were determined on the basis of ground motion by classifying sites using the multivariate site classification system. Low-rise structures with slight and moderate earthquake damage were noted to be concentrated in softer sites owing to the low focal depth of the site, topographical effects, and high frequency range of the mainshocks.
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Romero, Salome, Glenn J. Rix, and Steven P. French. "Transportation Routes in Soils Susceptible to Ground Failure: New Madrid Seismic Zone." Transportation Research Record: Journal of the Transportation Research Board 1736, no. 1 (January 2000): 127–33. http://dx.doi.org/10.3141/1736-16.
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Geologic deposits susceptible to ground motion amplification under seismic loading in the New Madrid Seismic Zone are delineated using multiple data sources including in situ measurements, geologic maps, and remote-sensing imagery. Soils are classified on the basis of the recommendations from the National Earthquake Hazards Reduction Program, which recommends a classification based on the average shear wave velocity of the geologic material in the upper 30 m. Measurements of shear wave velocity were obtained from Central United States Earthquake Consortium state geologists, the U.S. Geological Survey, and several researchers. However, since this is a predominantly rural area, limited field test data are available. Therefore, several other data sources are introduced including geologic maps and remote-sensing imagery to extrapolate dynamic properties in areas lacking extensive field measurements. Each data source was incorporated into a geographic information system for subsequent analysis. Bridges susceptible to failure from amplification of seismic waves and located on key transportation routes are identified for subsequent risk assessment or seismic retrofitting since the performance of these structures affects disaster planning and rescue efforts and may have severe consequences for the national economy.
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Volochiy, Bohdan, Mykhailo Zmysnyi, Leonid Ozirkovskyy, Volodomyr Onyschchenko, and Yuriy Salnyk. "IMPROVEMENT OF FIDELITY OF MOVING OBJECTS CLASSIFICATION IN GUARD SIGNALING COMPLEXES WITH SEISMIC SENSORS." Informatyka Automatyka Pomiary w Gospodarce i Ochronie Środowiska 8, no. 4 (December 16, 2018): 36–39. http://dx.doi.org/10.5604/01.3001.0012.8025.
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The effectiveness of guard signaling complexes (GSC), when there is an important validity of the classification of moving objects (MO), is evaluated by the following indexes: probability of GSC task execution; probability of partial fulfillment of the task; probability of user’s “deception”. Accordingly, the performance indicators of the GSC, in turn, depend on the indexes of the functionality of its constituents: probability of fixation of moving object by seismic sensor, probability of correct classification of MO type and probability of receiving radio signal by the system of receiving and displaying information (SRDI). The article describes a discrete-continuous stochastic model of of GSC reaction to moving object crossing control zone, in which three seismic sensors are installed. Majority principle of identifying the type of moving object was used on the receiving part of the complex. A comparative analysis of the effectiveness of guard signaling complexes using one, two and three sensors in control zone are carried out.
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Rahmani, Mohamed Elhadi, Abdelmalek Amine, and Reda Mohamed Hamou. "Clustering Based Sampling for Learning from Unbalanced Seismic Data Set." International Journal of Geotechnical Earthquake Engineering 8, no. 2 (July 2017): 1–22. http://dx.doi.org/10.4018/ijgee.2017070101.
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This article describes how some stratum contain a stress concentration zones, and while the stress increases and exceeds a high value or so called critical value, it destroys rocks. This causes the emission of seismic tremors of different energies. Seismology consists of the study of the effects of seismic waves, and predicting the seismic hazards to rocks and long wall coals. This is alongside the main problem occurred in this field, the unbalanced data that lacks cause when studying the seismic hazards. Learning from unbalanced data is considered as one of the most difficult issues to solve nowadays, this article presents an informed sampling method that is based on a clustering approach for the prediction of seismic hazards in Polish coal mines. The idea is based on the dividing of non-hazardous examples which represents more than 90% of the real-life cases into subsets of examples in order to balance the classes. This action facilitates the learning from the recorded data. For evaluation, the authors have evaluated the system based on the prediction of seismic hazards where positive results have been reviewed compared to the classification of examples without balancing the cases.
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Ryberg, Trond, Moritz Kirsch, Christian Haberland, Raimon Tolosana-Delgado, Andrea Viezzoli, and Richard Gloaguen. "Ambient seismic noise analysis of LARGE-N data for mineral exploration in the Central Erzgebirge, Germany." Solid Earth 13, no. 3 (March 14, 2022): 519–33. http://dx.doi.org/10.5194/se-13-519-2022.
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Abstract. Ambient seismic noise tomography is a novel, low-impact method for investigating the earth's structure. Although most passive seismic studies focus on structures on crustal scales, there are only a few examples of this technique being applied in a mineral exploration context. In this study, we performed an ambient seismic experiment to ascertain the relationship between the shallow shear wave velocity and mineralized zones in the Erzgebirge in Germany, one of the most important metal provinces in Europe. Late Variscan mineralized greisen and veins occurring in the Geyer-Ehrenfriedersdorf mining district of the Central Erzgebirge were mined from medieval times until the end of the 19th century. These occurrences represent a significant resource for commodities of high economic importance, such as tin, tungsten, zinc, indium, bismuth and lithium. Based on ambient noise data from a dense “LARGE-N” network comprising 400 low-power, short-period seismic stations, we applied an innovative tomographic inversion technique based on Bayesian statistics (transdimensional, hierarchical Monte Carlo search with Markov Chains using a Metropolis/Hastings sampler) to derive a three-dimensional shear wave velocity model. An auxiliary 3D airborne time-domain electromagnetic dataset is used to provide additional insight into the subsurface architecture of the area. The velocity model shows distinct anomalies down to approximately 500 m depth that correspond to known geological features of the study area, such as (a) gneiss intercalations in the mica schist-dominated host rock, imaged by a SW–NE striking low-velocity zone with a moderately steep northerly dip, and (b) a NW-trending strike-slip fault, imaged as a subvertical linear zone cross-cutting and offsetting this low-velocity domain. Similar to the velocity data, the electromagnetic data exhibit north-dipping (high-conductivity) structures in the mica schists, corresponding to the strike and dip of the predominant metamorphic fabric. An unsupervised classification performed on the bivariate 3D dataset yielded nine spatially coherent classes, one of which shows a high correspondence with drilled greisen occurrences in the roof zone of a granite pluton. The relatively high mean shear velocity and resistivity values of this class could be explained by changes in density and composition during greisen formation, as observed in other areas of the Erzgebirge. Our study demonstrates the great potential of the cost-efficient and low-impact ambient noise technology for mineral exploration, especially when combined with other independent geophysical datasets.
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Heck, Matthias, Conny Hammer, Alec van Herwijnen, Jürg Schweizer, and Donat Fäh. "Automatic detection of snow avalanches in continuous seismic data using hidden Markov models." Natural Hazards and Earth System Sciences 18, no. 1 (January 25, 2018): 383–96. http://dx.doi.org/10.5194/nhess-18-383-2018.
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Abstract. Snow avalanches generate seismic signals as many other mass movements. Detection of avalanches by seismic monitoring is highly relevant to assess avalanche danger. In contrast to other seismic events, signals generated by avalanches do not have a characteristic first arrival nor is it possible to detect different wave phases. In addition, the moving source character of avalanches increases the intricacy of the signals. Although it is possible to visually detect seismic signals produced by avalanches, reliable automatic detection methods for all types of avalanches do not exist yet. We therefore evaluate whether hidden Markov models (HMMs) are suitable for the automatic detection of avalanches in continuous seismic data. We analyzed data recorded during the winter season 2010 by a seismic array deployed in an avalanche starting zone above Davos, Switzerland. We re-evaluated a reference catalogue containing 385 events by grouping the events in seven probability classes. Since most of the data consist of noise, we first applied a simple amplitude threshold to reduce the amount of data. As first classification results were unsatisfying, we analyzed the temporal behavior of the seismic signals for the whole data set and found that there is a high variability in the seismic signals. We therefore applied further post-processing steps to reduce the number of false alarms by defining a minimal duration for the detected event, implementing a voting-based approach and analyzing the coherence of the detected events. We obtained the best classification results for events detected by at least five sensors and with a minimal duration of 12 s. These processing steps allowed identifying two periods of high avalanche activity, suggesting that HMMs are suitable for the automatic detection of avalanches in seismic data. However, our results also showed that more sensitive sensors and more appropriate sensor locations are needed to improve the signal-to-noise ratio of the signals and therefore the classification.
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Fortunatova, N. K., A. I. Varlamov, A. S. Kanev, V. I. Poroskun, A. V. Baranova, and M. A. Bushueva. "Structure and Assessment of the Oil Potential of Carbonaceous Carbonate-Siliceous Domanik Deposits in the Volga–Ural Oil and Gas Province." Russian Geology and Geophysics 62, no. 08 (August 1, 2021): 929–46. http://dx.doi.org/10.2113/rgg20214351.
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Abstract —The paper considers the regularities in the structure and conditions of formation of Domanik carbonaceous carbonate-siliceous productive deposits. They are shown to occur in the stratigraphic interval from middle Frasnian to upper Famennian. The highly persistent structure of their sections for many kilometers within specific sedimentation zones and the drastic changes in the structure at the boundaries of the zones are justified. Lithological classification of rocks is considered. Methods and results of combined paleontological, lithological, geochemical, and petrophysical core studies are presented, as well as interpretation of well logging data and seismic-survey materials used in the assessment of oil resources and identification of oil- and gas-promising zones and areas. The conducted studies have proved significant oil resources in the Domanik productive sequence; their extraction might compensate for the decline in oil production from conventional pools.
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Bredesen, Kenneth, Mads Lorentzen, Lars Nielsen, and Klaus Mosegaard. "Quantitative seismic interpretation of the Lower Cretaceous reservoirs in the Valdemar Field, Danish North Sea." Petroleum Geoscience 27, no. 4 (July 19, 2021): petgeo2021–016. http://dx.doi.org/10.1144/petgeo2021-016.
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A quantitative seismic interpretation study is presented for the Lower Cretaceous Tuxen reservoir in the Valdemar Field, which is associated with heterogeneous and complex geology. Our objective is to better outline the reservoir quality variations of the Tuxen reservoir across the Valdemar Field. Seismic pre-stack data and well logs from two appraisal wells form the basis of this study. The workflow used includes seismic and rock physics forward modelling, attribute analysis, a coloured inversion, and a Bayesian pre-stack inversion for litho-fluid classification. Based on log data, the rock physics properties of the Tuxen interval reveal that the seismic signal is more governed by porosity than water-saturation changes at near-offset (or small angle). The coloured and Bayesian inversion results were generally consistent with well-log observations at the reservoir level and conformed to interpreted horizons. Although the available data have some limitations and the geological setting is complex, the results implied more promising reservoir quality in some areas than others. Hence, the results may offer useful information for delineating the best reservoir zones for further field development and selecting appropriate production strategies.
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Van Herwijnen, Alec, and Jürg Schweizer. "Seismic sensor array for monitoring an avalanche start zone: design, deployment and preliminary results." Journal of Glaciology 57, no. 202 (2011): 267–76. http://dx.doi.org/10.3189/002214311796405933.
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AbstractIn snow, acoustic emissions originate from the breaking of bonds between snow crystals and the formation of cracks. Previous research has shown that acoustic signals emanate from a natural snowpack. The relation between these signals and the stability of the snowpack has thus far remained elusive. Studies on other hazardous gravitational processes suggest that damage accumulation precedes major failure. If increased cracking activity could be detected in snow this might be used for avalanche prediction. We report on the development of a seismic sensor array to continuously monitor acoustic emissions in an avalanche start zone. During three winters, over 1400 sensor days of continuous acoustic data were collected. With the aid of automatic cameras and a microphone the main types of background noise were identified. Seismic signals generated by avalanches were also identified. Spectrograms from seismic signals generated by avalanches exhibit a unique triangular shape unlike any source of background noise, suggesting that automatic detection and classification of events is possible. Furthermore, discriminating between loose-snow and snow-slab avalanches is possible. Thus far we have not identified precursor events for natural dry-snow slab avalanche release. Detailed investigation of one dry-snow slab avalanche showed that signals observed prior to the release originated from background noise or small loose-snow avalanches.
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Doetsch, Joseph, Niklas Linde, Ilaria Coscia, Stewart A. Greenhalgh, and Alan G. Green. "Zonation for 3D aquifer characterization based on joint inversions of multimethod crosshole geophysical data." GEOPHYSICS 75, no. 6 (November 2010): G53—G64. http://dx.doi.org/10.1190/1.3496476.
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Predictive groundwater modeling requires accurate information about aquifer characteristics. Geophysical imaging is a powerful tool for delineating aquifer properties at an appropriate scale and resolution, but it suffers from problems of ambiguity. One way to overcome such limitations is to adopt a simultaneous multitechnique inversion strategy. We have developed a methodology for aquifer characterization based on structural joint inversion of multiple geophysical data sets followed by clustering to form zones and subsequent inversion for zonal parameters. Joint inversions based on cross-gradient structural constraints require less restrictive assumptions than, say, applying predefined petrophysical relationships and generally yield superior results. This approach has, for the first time, been applied to three geophysical data types in three dimensions. A classification scheme using maximum likelihood estimation is used to determine theparameters of a Gaussian mixture model that defines zonal geometries from joint-inversion tomograms. The resulting zones are used to estimate representative geophysical parameters of each zone, which are then used for field-scale petrophysical analysis. A synthetic study demonstrated how joint inversion of seismic and radar traveltimes and electrical resistance tomography (ERT) data greatly reduces misclassification of zones (down from 21.3% to 3.7%) and improves the accuracy of retrieved zonal parameters (from 1.8% to 0.3%) compared to individual inversions. We applied our scheme to a data set collected in northeastern Switzerland to delineate lithologic subunits within a gravel aquifer. The inversion models resolve three principal subhorizontal units along with some important 3D heterogeneity. Petrophysical analysis of the zonal parameters indicated approximately 30% variation in porosity within the gravel aquifer and an increasing fraction of finer sediments with depth.
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Iturrarán-Viveros, Ursula, Andrés M. Muñoz-García, Jorge O. Parra, and Josué Tago. "Validated artificial neural networks in determining petrophysical properties: A case study from Colombia." Interpretation 6, no. 4 (November 1, 2018): T1067—T1080. http://dx.doi.org/10.1190/int-2018-0011.1.
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We have applied instantaneous seismic attributes to a stacked P-wave reflected seismic section in the Tenerife field located in the Middle Magdalena Valley Basin in Colombia to estimate the volume of clay [Formula: see text] and the density [Formula: see text] at seismic scale. The well logs and the seismic attributes associated to the seismic trace closer to one of the available wells (Tenerife-2) is the information used to train some multilayered artificial neural networks (ANN). We perform data analysis via the gamma test, a mathematically nonparametric nonlinear smooth modeling tool, to choose the best input combination of seismic attributes to train ANNs to estimate [Formula: see text] and [Formula: see text]. Once the ANNs are trained, they are applied to predict these parameters along the seismic line. From the continuous estimations of [Formula: see text], we distinguish two facies: sands for [Formula: see text] and shales when [Formula: see text]. These estimations confirm the production of the Mugrosa C-Sands zone, and we draw the brown shale that correlates with the high-amplitude attributes and the yellow sand that correlates with the low-amplitude attributes. Using the well-log information for [Formula: see text] and the facies classification (also in the well log), two cubic polynomials that depend on time (or depth) are obtained, one for sands and the other for shales, to fit the [Formula: see text]. These two cubic polynomials and the facies classification obtained from the [Formula: see text] at the seismic scale enable us to estimate [Formula: see text] at the seismic scale. To validate the 2D [Formula: see text] and [Formula: see text] predicted data, a forward-modeling software (the Kennett reflectivity algorithm) is used. This model calculates synthetic seismograms that are compared with the real seismograms. This comparison indicates a small misfit that suggests that the [Formula: see text] and [Formula: see text] images are representing the reservoir description characteristics and the ANN method is accurate to map these parameters.
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Carcione, José M. "Amplitude variations with offset of pressure‐seal reflections." GEOPHYSICS 66, no. 1 (January 2001): 283–93. http://dx.doi.org/10.1190/1.1444907.
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Knowledge of pressure compartments is essential for identifying potential risks in advance of drilling and in understanding the mechanism of hydrocarbon trapping and migration. These compartments are bounded by pressure seals which, under certain conditions, can be detected and characterized with seismic reflection data. Use of prestack seismic data requires the analysis of reflections generated at the pressure seals, such as the top of a reservoir, rather than the properties of the rock volume. In this sense, amplitude variations with offset (AVO) techniques can be a good tool to obtain information from such pressure seals or pressure transition zones. In this work, I investigate the AVO response of compartment seals by analyzing the plane‐wave reflection coefficients as a function of pore pressure (above and below the seal), incidence angle, and seal thickness. For the case investigated in this work (Berea sandstone with high gas saturation), the AVO effects are important at low effective pressures, that is, when the pore pressure approaches the confining pressure. In shale‐free transition zones, the anomaly is, in general, negative, whereas in shale/sandstone sequences, the anomaly can be positive or negative depending on seal thickness and formation pressure. In terms of the four‐category classification for AVO crossplotting, the PP anomalies are mainly class IV and class I.
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Sharma, Ritesh Kumar, Satinder Chopra, and Larry Lines. "Seismic reservoir characterization of the Bone Spring and Wolfcamp Formations in the Delaware Basin: Challenges and uncertainty in characterization using rock physics — A case study: Part 2." Interpretation 8, no. 4 (November 1, 2020): T1057—T1069. http://dx.doi.org/10.1190/int-2020-0002.1.
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The discrimination of fluid content and lithology in a reservoir is important because it has a bearing on reservoir development and its management. Among other things, rock-physics analysis is usually carried out to distinguish between the lithology and fluid components of a reservoir by way of estimating the volume of clay, water saturation, and porosity using seismic data. Although these rock-physics parameters are easy to compute for conventional plays, there are many uncertainties in their estimation for unconventional plays, especially where multiple zones need to be characterized simultaneously. We have evaluated such uncertainties with reference to a data set from the Delaware Basin where the Bone Spring, Wolfcamp, Barnett, and Mississippian Formations are the prospective zones. Attempts at seismic reservoir characterization of these formations have been developed in Part 1 of this paper, where the geologic background of the area of study, the preconditioning of prestack seismic data, well-log correlation, accounting for the temporal and lateral variation in the seismic wavelets, and building of robust low-frequency model for prestack simultaneous impedance inversion were determined. We determine the challenges and the uncertainty in the characterization of the Bone Spring, Wolfcamp, Barnett, and Mississippian sections and explain how we overcame those. In the light of these uncertainties, we decide that any deterministic approach for characterization of the target formations of interest may not be appropriate and we build a case for adopting a robust statistical approach. Making use of neutron porosity and density porosity well-log data in the formations of interest, we determine how the type of shale, volume of shale, effective porosity, and lithoclassification can be carried out. Using the available log data, multimineral analysis was also carried out using a nonlinear optimization approach, which lent support to our facies classification. We then extend this exercise to derived seismic attributes for determination of the lithofacies volumes and their probabilities, together with their correlations with the facies information derived from mud log data.
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Verkholantsev, F., R. Diagilev, I. Golubeva, and N. Guseva. "EARTHQUAKE MAY 20, 2014, ML=2.8, I0=4–5 IN THE CENTRAL PART OF THE REPUBLIC OF BASHKORTOSTAN." Earthquakes in Northern Eurasia, no. 23 (December 15, 2020): 317–22. http://dx.doi.org/10.35540/1818-6254.2020.23.32.
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The article provides macroseismic data on the earthquake 20.05.2014 18h26mUTC ML=2.8, that had a local but relatively strong macroseismic effect (I0=4–5) in the Chishminsky district of the Republic of Bashkortostan. After the event, macroseismic data were collected in 27 settlements in the epicentral zone. This data allowed to determine the macroseismic epicenter, which is close to the instrumental one. The events in the same area during the historical period were considered in detail and modern seismic records were revised. The data allowed to identify a series of similar seismic events with less magnitudes in 2014. The classification of these activities into two groups has been justified there. There are tectonic and natural events induced by Alkinskoye oil deposit exploration.
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Greenhalgh, Scott R., John H. McBride, John M. Bartley, R. William Keach, Brooks B. Britt, and Bart J. Kowallis. "Along-strike variability of thrust fault vergence." Interpretation 3, no. 3 (August 1, 2015): SX1—SX12. http://dx.doi.org/10.1190/int-2014-0182.1.
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The 3D kinematic evolution of thrust systems, in which vergence changes along strike, is poorly understood. This study uses 3D seismic data from Big Piney-LaBarge field, Wyoming, to examine the geometry and kinematics of two faults at the leading edge of the Hogsback thrust sheet, the frontal thrust of the Late Cretaceous Sevier fold-thrust belt. These thrusts lie along strike of each another and share an east-vergent detachment within the Cretaceous Baxter Shale. The two thrusts verge in opposite directions: The southern thrust verges eastward forming a frontal ramp consistent with major thrusts of the Sevier belt, whereas the northern thrust verges westward to form a type 1 triangle zone with the Hogsback thrust. The thrusts have strike lengths of 5 km (3.1 mi) and 8 km (5.0 mi), respectively, and they are separated by a transfer zone of less than 0.5 km (0.3 mi) wide. Strata in the transfer zone appear to be relatively undeformed, but reflections are less coherent here, which suggests small offsets unresolved by the seismic survey. Retrodeformable cross sections and a structure contour map on the Cretaceous Mesaverde Group indicate that shortening varies along strike, with a pronounced minimum at the transfer zone and greater shortening across the northern, west-vergent thrust (610 m [2000 ft]) than across the southern, east-vergent thrust (230 m [755 ft]). Mapping of these thrusts suggests that they propagated laterally toward each other to form a type 1 antithetic fault linkage in the transfer zone. Spatial patterns expressed in seismic attributes in and near the detachment horizon, which include waveform classification and spectral decomposition, suggest that stratigraphic variations may have pinned the detachment, thus localizing the transfer zone. Thickness variations in the thrust sheet also may have influenced the thrust geometry. Our study provides an analog for analysis of similar complex contractional belts around the world.
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Shahbazi, Shahrokh, Iman Mansouri, Jong Wan Hu, and Armin Karami. "Effect of Soil Classification on Seismic Behavior of SMFs considering Soil-Structure Interaction and Near-Field Earthquakes." Shock and Vibration 2018 (October 8, 2018): 1–17. http://dx.doi.org/10.1155/2018/4193469.
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Seismic response of a structure is affected by its dynamic properties and soil flexibility does not have an impact on it when the bottom soil of foundation is supposedly frigid, and the soil flexibility is also ignored. Hence, utilizing the results obtained through fixed-base buildings can lead to having an insecure design. Being close to the source of an earthquake production causes the majority of earthquake’s energy to reach the structure as a long-period pulse. Therefore, near-field earthquakes produce many seismic needs so that they force the structure to dissipate output energy by relatively large displacements. Hence, in this paper, the seismic response of 5- and 8-story steel buildings equipped with special moment frames (SMFs) which have been designed based on type-II and III soils (according to the seismic code of Iran-Standard 2800) has been studied. The effects of soil-structure interaction and modeling of the panel zone were considered in all of the two structures. In order to model radiation damping and prevent the reflection of outward propagating dilatational and shear waves back into the model, the vertical and horizontal Lysmer–Kuhlemeyer dashpots as seen in the figures are adopted in the free-field boundary of soil. The selected near- and far-field records were used in the nonlinear time-history analysis, and structure response was compared in both states. The results obtained from the analysis showed that the values for the shear force, displacement, column axial force, and column moment force on type-III soil are greater than the corresponding values on type-II soil; however, it cannot be discussed for drift in general.
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Naji, Dalia Munaff, Muge K. Akin, and Ali Firat Cabalar. "A Comparative Study on the VS30 and N30 Based Seismic Site Classification in Kahramanmaras, Turkey." Advances in Civil Engineering 2020 (November 3, 2020): 1–15. http://dx.doi.org/10.1155/2020/8862827.
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Assessment of seismic site classification (SSC) using either the average shear wave velocity (VS30) or the average SPT-N values (N30) for upper 30 m in soils is the simplest method to carry out various studies including site response and soil-structure interactions. Either the VS30- or the N30-based SSC maps designed according to the National Earthquake Hazards Reduction Program (NEHRP) classification system are effectively used to predict possible locations for future seismic events. The main goal of this study is to generate maps using the Geographic Information System (GIS) for the SSC in Kahramanmaras city, influenced by both East Anatolian Fault and Dead Sea Fault Zones, using both VS30 and N30 values. The study also presents a series of GIS maps produced using the shear wave velocity (VS) and SPT-N values at the depths of 5 m, 10 m, 15 m, 20 m, and 25 m. Furthermore, the study estimates the bed rock level and generates the SSC maps for the average VS values through overburden soils by using the NEHRP system. The VS30 maps categorize the study area mainly under class C and limited number of areas under classes B and D, whereas the N30 maps classify the study area mainly under class D. Both maps indicate that the soil classes in the study area are different to a high extent. Eventually, the GIS maps complied for the purpose of urban development may be utilized effectively by engineers in the field.
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Eladj, S., T. K. Lounissi, M. Z. Doghmane, and M. Djeddi. "Lithological Characterization by Simultaneous Seismic Inversion in Algerian South Eastern Field." Engineering, Technology & Applied Science Research 10, no. 1 (February 3, 2020): 5251–58. http://dx.doi.org/10.48084/etasr.3203.
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The main goal of this paper is to characterize a reservoir situated in the southeast of Algeria based on AVO seismic inversion. The seismic inversion model has been built by the iterative method of Aki and Richards’s approximation and it has been correlated with four-existing wells in the studied zone. The correlation rate between the inversion model and logging data is good (varying from 72% to 85%). Reservoir characterization of this field has been given in detail. The lithological description is used to construct a Geomechanical model that is useful for new wells’ drilling decisions. The high correlated results allowed us to have a vision on the horizontal variation of Petrophysical parameters such as density and lithological variation of three facies clay, tight limestone, and porous limestone. Moreover, this classification is used in the best way to determine the interesting zone with higher porosity values, so that the exploration strategy becomes more efficient with minimized uncertainties. Therefore, it is highly recommended to use the constructed model to propose new wells as well-5 in this study.
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Alexopoulos, John D., Nicholas Voulgaris, Spyridon Dilalos, Vasileios Gkosios, Ioannis-Konstantinos Giannopoulos, Georgia S. Mitsika, Emmanuel Vassilakis, Vassilis Sakkas, and George Kaviris. "Near-Surface Geophysical Characterization of Lithologies in Corfu and Lefkada Towns (Ionian Islands, Greece)." Geosciences 12, no. 12 (December 3, 2022): 446. http://dx.doi.org/10.3390/geosciences12120446.
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Lefkada and Corfu old towns are located in the western part of Greece, in the Ionian Sea. Their proximity to the Hellenic subduction zone (HSZ) is the reason for their intense seismicity. The main goal of this study was the estimation of the geotechnical characteristics of the subsurface, with the contribution of applied geophysical techniques. Therefore, seismic refraction tomography (SRT) and multichannel analysis of surface waves (MASW) were applied. A total of thirty-three (33) seismic and geoelectrical profiles were performed in both towns in order to evaluate the geotechnical characteristics of the subsurface formations. Additionally, subsurface resistivity distributions were investigated with the application of electrical resistivity tomography (ERT). Some important elastic moduli were calculated through the combination of estimated seismic wave velocities and laboratory density measurements. The horizontal distribution of seismic velocities and mechanical properties (σ, E, K, G) of Corfu town was illustrated in maps, for the depth of 5 m. The geophysical interpretation also revealed that Lefkada’s subsurface consists of only one compact geological formation, with little or no variation of its geophysical-geotechnical characteristics. Beyond that, the ground type classifications for the two towns were determined according to the European Committee for Standardization Eurocode 8, based on VS30 values.
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Putilov, Ivan S., Ekaterina E. Vinokurova, Anastasiia A. Guliaeva, Aleksey L. Yuzhakov, and Nikita A. Popov. "Conceptual Geological Modelling based on Lithological and Petrographic Studies (The Case of the Permo-Carboniferous Deposit of the Usinskoye Field)." Вестник Пермского национального исследовательского политехнического университета. Геология. Нефтегазовое и горное дело 20, no. 3 (August 2020): 214–22. http://dx.doi.org/10.15593/2712-8008/2020.3.2.
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The work intends to develop a conceptual model of the Permo-Carboniferous deposit of the Usinskoye field. In the furtherance of this goal, the authors have addressed the tasks of designing a specialised table format to describe thin sections of carbonate core samples and create a database based on the developed format for the subsequent analysis. The paper deals with studying the Permo-Carboniferous deposit of the Usinskoye field, located in the Komi Republic. A unique database of 1,710 described thin sections from 12 wells was created based on the developed format. The classification of carbonate rocks by R.J. Dunham supplemented by Embry and Kloven (based on the dominating fabric in limestone, type of cementing agent and their relationships in the rock) was used as a basis. According to rock material compositions and textural properties, the following nine rock lithotypes were identified: Mudstone, Wackestone, Packstone, Grainstone, Boundstone, Floatstone, Rudstone, Crystalline Carbonate (Dolomite), and Clayey Carbonate Silicite. By following the rock lithology type identification results and the seismic data, three main facies zones were determined in the section of the mid- Carboniferous and Lower Permian sediments: carbonate shoal (inner ramp zone), organogenic buildup (middle ramp zone) and shallow marine shelf plain (mid-ramp zone, partially outer ramp zone). A moderately deep marine shelf plain facies (outer ramp zone) was provisionally defined. Following the study results, two profiles of the Mid-Carboniferous and Lower Permian sediments of the Usinskoye field were plotted along two well lines. The presented sections support the conceptual model developed. Based on the core sample findings, the zone of organogenic build-ups stands out in the eastern part of the field, dating back predominantly to the Late Carboniferous and Early Permian periods. An inner ramp with the carbonate shoal facies supposedly exists in the field north-west. The conducted work has resulted in the development of a conceptual model of the Permo-Carboniferous deposit of the Usinskoye field, which can be used for further development of more reliable 3D facies models, commercial-scale estimations of reserves and field development designs.
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Gitis, Valery, and Alexander Derendyaev. "From monitoring of seismic fields to the automatic forecasting of earthquakes." International Journal of Web Information Systems 15, no. 5 (December 2, 2019): 535–49. http://dx.doi.org/10.1108/ijwis-12-2018-0087.
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Purpose The purpose of this paper is to offer two Web-based platforms for systematic analysis of seismic processes. Both platforms are designed to analyze and forecast the state of the environment and, in particular, the level of seismic hazard. The first platform analyzes the fields representing the properties of the seismic process; the second platform forecasts strong earthquakes. Earthquake forecasting is based on a new one-class classification method. Design/methodology/approach The paper suggests an approach to systematic forecasting of earthquakes and examines the results of tests. This approach is based on a new method of machine learning, called the method of the minimum area of alarm. The method allows to construct a forecast rule that optimizes the probability of detecting target earthquakes in a learning sample set, provided that the area of the alarm zone does not exceed a predetermined one. Findings The paper presents two platforms alongside the method of analysis. It was shown that these platforms can be used for systematic analysis of seismic process. By testing of the earthquake forecasting method in several regions, it was shown that the method of the minimum area of alarm has satisfactory forecast quality. Originality/value The described technology has two advantages: simplicity of configuration for a new problem area and a combination of interactive easy analysis supported by intuitive operations and a simplified user interface with a detailed, comprehensive analysis of spatio-temporal processes intended for specialists. The method of the minimum area of alarm solves the problem of one-class classification. The method is original. It uses in training the precedents of anomalous objects and statistically takes into account normal objects.
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De Angelis, Alessandra, Fabrizio Ascione, Rosa Francesca De Masi, Maria Rosaria Pecce, and Giuseppe Peter Vanoli. "A Novel Contribution for Resilient Buildings. Theoretical Fragility Curves: Interaction between Energy and Structural Behavior for Reinforced Concrete Buildings." Buildings 10, no. 11 (October 27, 2020): 194. http://dx.doi.org/10.3390/buildings10110194.
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The paper introduces a new semi-probabilistic methodology for the definition of energy fragility curves suitable for a macro-classification of building stock inspired to and coupled with the widely adopted method of seismic fragility curves. The approach is applied to the reinforced concrete residential buildings of the Italian stock. Starting from a classification according to the climatic zone and the construction period, some reference buildings in terms of building envelope typologies have been defined and simulated by means of dynamic modeling tools. Then, cumulative distributions of the probability that the primary energy consumption for heating was comparable with certain threshold values are defined according to the climatic conditions expressed with the heating degree days, which constitute the intensity measure for the fragility curves. Finally, by focusing on the interaction points between structural and energetic aspects, it is shown how these curves can be useful for decision-makers with regards to definition of importance and or the level of intervention to be made to the building envelope for improving its seismic safety and the energy quality. Indeed, non-integrated interventions are more expensive and less efficient.
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Kokošin, Jure, and Andrej Gosar. "Seismic Microzonation of Breginjski Kot (NW Slovenia) Based on Detailed Engineering Geological Mapping." Scientific World Journal 2013 (2013): 1–12. http://dx.doi.org/10.1155/2013/626854.
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Breginjski kot is among the most endangered seismic zones in Slovenia with the seismic hazard assessed to intensity IX MSK and the design ground acceleration of 0.250 g, both for 500-year return period. The most destructive was the 1976 Friuli Mw = 6.4 earthquake which had maximum intensity VIII-IX. Since the previous microzonation of the area was based solely on the basic geological map and did not include supplementary field research, we have performed a new soil classification of the area. First, a detailed engineering geological mapping in scale 1 : 5.000 was conducted. Mapped units were described in detail and some of them interpreted anew. Stiff sites are composed of hard to medium-hard rocks which were subjected to erosion mainly evoked by glacial and postglacial age. At that time a prominent topography was formed and different types of sediments were deposited in valleys by mass flows. A distinction between sediments and weathered rocks, their exact position, and thickness are of significant importance for microzonation. On the basis of geological mapping, a soil classification was carried out according to the Medvedev method (intensity increments) and the Eurocode 8 standard (soil factors) and two microzonation maps were prepared. The bulk of the studied area is covered by soft sediments and nine out of ten settlements are situated on them. The microzonation clearly points out the dependence of damage distribution in the case of 1976 Friuli earthquake to local site effects.
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Zafirovski, Zlatko, Igor Pesevski, and Jovan Papic. "Methodology for extrapolation of rock mass deformability parameters in tunneling." Facta universitatis - series: Architecture and Civil Engineering 10, no. 3 (2012): 235–44. http://dx.doi.org/10.2298/fuace1203235z.
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This article proposes one approach for extrapolation of necessary parameters for numerical analyses in tunnelling. The approach is named as an empirical - statical - dynamical method for extrapolation. The proposed methodology is based on combination of empirical classification rock mass methods, geophysical measurements and direct dilatometer deformability testing on a field. The analyses are prepared for purposes of investigation and design for several tunnels in Republic of Macedonia. One example for dividing of tunnel length in quasi-homogenous zones, as a basis for forming of geotechnical and numerical model that can be a basis for interaction analyses of rock - structures system and stress-strain behaviour of rock massif, is also given. The several original regressive models between rock mass quality, deformability and velocity of longitudinal seismic waves are shown.
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Qadri, S. M. Talha, M. Qasim Mirza, Afia Raja, Saman Yaghmaei-Sabegh, Mohammed Hail Hakimi, Syed Haroon Ali, and Mohammad Younis Khan. "Application of Probabilistic Seismic Hazard Assessment to Understand the Earthquake Hazard in Attock City, Pakistan: A Step towards Linking Hazards and Sustainability." Sustainability 15, no. 2 (January 5, 2023): 1023. http://dx.doi.org/10.3390/su15021023.
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Within the last three decades, twelve major earthquakes (Mw > 6.0) have jolted Pakistan and contributed to a heavy death toll and an economic loss of billions of dollars, which is immense for any underdeveloped country. Despite the generalized description of seismic hazards in various regions of Pakistan, densely populated cities still require a detailed and integrated vulnerability analysis to overcome the impact of a significant earthquake. This study aims to integrate seismic hazard assessment schemes to understand the vulnerability of Attock city against an earthquake. It initially evaluates the threat from an earthquake due to tectonic activity in the region, splits the region (about 200 km radius) into six seismic zones and uses area source parameters. The ground motion prediction equations compatible with the study area’s seismotectonic environment are also used in this study. Peak horizontal ground acceleration (PGA) and 5% damped spectral acceleration are critical features of ground motions. The site classification is carried within Attock city, indicating the presence of SB (foundation condition with Vs30 = 760 m/s), SC (foundation condition with Vs30 = 400 m/s) and SD (foundation condition with Vs30 = 300 m/s). The peak ground accelerations for a return period of 475 years at the SB, SC and SD sites are estimated as 0.23 g, 0.28 g and 0.30 g, respectively. Uniform hazard spectra are obtained for each site classification at three return periods (475, 975 and 2475 years). Another possible threat can be the local site conditions of the study area, as Attock city exists on the unlithified sediments of upper Pleistocene to Recent alluvial deposits. That is why microtremor recordings are conducted at 20 sites within Attock city to understand the fundamental frequency (f0), horizontal to vertical spectral amplitude (A0) and Kg parameter, a seismic vulnerability index. The values of f0 are found between 0.6 and 9 Hz and A0 is observed between 2.1 and 5 Hz, whereas the Kg is estimated between 0.24 and 20 Hz. Despite evidence of the seismic vulnerability of Attock city, the current building designs and infrastructure development are not synchronized with the uniform hazard response spectra and the soil amplification, thus enhancing the exposure of the study area to disaster during a major earthquake. This study will be instrumental in pre-disaster mitigation strategies for urban planners and policymakers.
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Kuyuk, H. S., E. Yildirim, E. Dogan, and G. Horasan. "Application of <i>k</i>-means and Gaussian mixture model for classification of seismic activities in Istanbul." Nonlinear Processes in Geophysics 19, no. 4 (August 3, 2012): 411–19. http://dx.doi.org/10.5194/npg-19-411-2012.
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Abstract. Two unsupervised pattern recognition algorithms, k-means, and Gaussian mixture model (GMM) analyses have been applied to classify seismic events in the vicinity of Istanbul. Earthquakes, which are occurring at different seismicity rates and extensions of the Thrace-Eskisehir Fault Zone and the North Anatolian Fault (NAF), Turkey, are being contaminated by quarries operated around Istanbul. We have used two time variant parameters, complexity, the ratio of integrated powers of the velocity seismogram, and S/P amplitude ratio as classifiers by using waveforms of 179 events (1.8 < M < 3.0). We have compared two algorithms with classical multivariate linear/quadratic discriminant analyses. The total accuracies of the models for GMM, k-means, linear discriminant function (LDF), and quadratic discriminant function (QDF) are 96.1%, 95.0%, 96.1%, 96.6%, respectively. The performances of models are discussed for earthquakes and quarry blasts separately. All methods clustered the seismic events acceptably where QDF slightly gave better improvements compared to others. We have found that unsupervised clustering algorithms, for which no a-prior target information is available, display a similar discriminatory power as supervised methods of discriminant analysis.
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Mesimeri, M., V. Karakostas, E. Papadimitriou, and G. Tsaklidis. "CHARACTERISTICS OF SEISMIC EXCITATIONS IN CORINTH GULF (GREECE)." Bulletin of the Geological Society of Greece 50, no. 3 (July 27, 2017): 1379. http://dx.doi.org/10.12681/bgsg.11851.
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Seismic excitations occur as mainshock-aftershock sequences (MS-AS) encompassing a strong event called mainshock with the largest magnitude in the set, or as earthquake swarms (ES) when a distinctive main event is absent. In regions as the gulf of Corinth, where active deformation is manifested with frequent seismicity bursts, it is important to distinguish MS-AS from ES for providing information on the physical process of earthquake generation and contribute to the seismic hazard assessment. For this purpose, a highly accurate local earthquake catalogue was compiled and an effort was made for clusters identification after establishing certain criteria based on spatio-temporal seismicity properties. The skewness and kurtosis of moment release history were calculated considering the normalized time of every event in a cluster since the starting time of the cluster and its seismic moment. For MS-AS we found large positive values for skewness and kurtosis contrary to ES that exhibit negative to low positive values for skewness and even lower values for kurtosis.In order to verify the classification of clusters, the b-value, the spatial size and the number of events of each cluster were examined. Finally, a scaling relation between the length of the rupture zone and magnitude derived for the MS-AS sequences.
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Clemente-Chavez, A., F. R. Zúñiga, J. Lermo, A. Figueroa-Soto, C. Valdés, M. Montiel, O. Chavez, and M. Arroyo. "On the behavior of site effects in central Mexico (the Mexican volcanic belt – MVB), based on records of shallow earthquakes that occurred in the zone between 1998 and 2011." Natural Hazards and Earth System Sciences 14, no. 6 (June 4, 2014): 1391–406. http://dx.doi.org/10.5194/nhess-14-1391-2014.
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Abstract. The Mexican volcanic belt (MVB) is a seismogenic zone that transects the central part of Mexico with an east–west orientation. The seismic risk and hazard of this seismogenic zone has not been studied in detail due to the scarcity of instrumental data as well as because seismicity in the continental regime of central Mexico is not too frequent. However, it is known that there are precedents of large earthquakes (Mw > 6.0) that have taken place in this zone. The valley of Mexico City (VM) is the sole zone, within the MVB, that has been studied in detail. Studies have mainly focused on the ground amplification during large events such as the 1985 subduction earthquake that occurred off coast of Michoacán. The purpose of this article is to analyze the behavior of site effects in the MVB zone based on records of shallow earthquakes (data not reported before) that occurred in the zone between 1998 and 2011. We present a general overview of site effects in the MVB, a classification of the stations in order to reduce the uncertainty in the data when obtaining attenuation parameters in future works, as well as some comparisons between the information presented here and that presented in previous studies. A regional evaluation of site effects and Fourier acceleration spectrum (FAS) shape was estimated based on 80 records of 22 shallow earthquakes within the MVB zone. Data of 25 stations were analyzed. Site effects were estimated by using the horizontal-to-vertical spectral ratio (HVSR) methodology. The results show that seismic waves are less amplified in the northeast sites of the MVB with respect to the rest of the zone and that it is possible to classify two groups of stations: (1) stations with negligible site amplification (NSA) and (2) stations with significant site amplification (SSA). Most of the sites in the first group showed small (<3) amplifications while the second group showed amplifications ranging from 4 to 6.5 at frequencies of about 0.35, 0.75, 15 and 23 Hz. With these groups of stations, average levels of amplification were contrasted for the first time with those caused by the subduction zone earthquakes. With respect to the FAS shapes, most of them showed similarities at similar epicentral distances. Finally, some variations of site effects were found when compared to those obtained in previous studies on different seismicity regions. These variations were attributed to the location of the source. These aspects help to advance the understanding about the amplification behavior and of the expected seismic risk on central Mexico due to large earthquakes within the MVB seismogenic zone.