Abstract Passive seismic denoising is mostly performed using a simple band-pass filter, which can be problematic when signal and noise share the same frequency band. More advanced passive seismic denoising methods take advantage of fixed-basis transforms, for example, the wavelet, to remove noise. Here, we present an open-source package for data-driven denoising based on adaptively learning sparse transform. Contrary to the fixed-basis transforms, the proposed method belongs to the adaptive-basis transforms. We learn the 1D features embedded in the passive seismic data from all the available waveform data sets without requiring spatial coherency in a data-driven way. Thus, the new method is flexible to apply in any passive seismic monitoring project because of its data-driven and single-channel nature when implemented. Considering the computationally expensive K-singular-value-decomposition (KSVD) in the traditional dictionary learning framework, we suggest applying a fast SVD-free dictionary learning method that can be readily applicable to process massive seismic data during passive seismic monitoring. The proposed method is applied to two synthetic data examples and three real passive seismic data sets to demonstrate its effectiveness in improving the signal-to-noise ratio, and its potential in applications like arrival picking. The open-source reproducible package can be found in the Data and Resources section.
{"title":"Dictionary Learning for Single-Channel Passive Seismic Denoising","authors":"Yangkang Chen, Alexandros Savvaidis, Sergey Fomel","doi":"10.1785/0220230169","DOIUrl":"https://doi.org/10.1785/0220230169","url":null,"abstract":"Abstract Passive seismic denoising is mostly performed using a simple band-pass filter, which can be problematic when signal and noise share the same frequency band. More advanced passive seismic denoising methods take advantage of fixed-basis transforms, for example, the wavelet, to remove noise. Here, we present an open-source package for data-driven denoising based on adaptively learning sparse transform. Contrary to the fixed-basis transforms, the proposed method belongs to the adaptive-basis transforms. We learn the 1D features embedded in the passive seismic data from all the available waveform data sets without requiring spatial coherency in a data-driven way. Thus, the new method is flexible to apply in any passive seismic monitoring project because of its data-driven and single-channel nature when implemented. Considering the computationally expensive K-singular-value-decomposition (KSVD) in the traditional dictionary learning framework, we suggest applying a fast SVD-free dictionary learning method that can be readily applicable to process massive seismic data during passive seismic monitoring. The proposed method is applied to two synthetic data examples and three real passive seismic data sets to demonstrate its effectiveness in improving the signal-to-noise ratio, and its potential in applications like arrival picking. The open-source reproducible package can be found in the Data and Resources section.","PeriodicalId":21687,"journal":{"name":"Seismological Research Letters","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135386289","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jonas A. Kintner, Kenneth Michael Cleveland, James Eric Pippin, Ryan Thomas Modrak, Brent Delbridge
Abstract The Source Physics Experiment (SPE) Phase I consisted of a series of over-buried, horizontally colocated chemical explosions at the Nevada National Security Site. Seismic waveforms from these explosions recorded at near-source accelerometers, local geophone arrays, and regional seismic stations provided a rich suite of observations suitable for resolving fine source details. To investigate the time-varying source history of the explosions, we used the frequency-domain moment-tensor inversion method described in Yang et al. (2018) with added regularization and reconstruction to suppress the nonuniqueness evident in unconstrained inversion results. The inverted moment-rate spectra are accurate within the response band of the local geophones and, in all cases, display predominately isotropic characteristics. For SPE-4Prime, SPE-5, and SPE-6, we resolve predominately isotropic moment release followed by double couple and compensated linear vector dipole (CLVD) release later in the time-varying source history. We interpret these results both in terms of absolute depth and scaled depth of burial. The apparent non-isotropic release from SPE-4Prime and SPE-5 may simply reflect increased resolving power related to improved Earth model accuracy at greater absolute depths, whereas the non-isotropic release from SPE-6 likely reflects the larger damage associated with an event at a shallower scaled depth. These results provide insight into the time-varying source characteristics of shallow explosions and motivation to study shear-wave generation by inverting for fracture, spallation, induced slip, and other temporally delayed source processes through time-varying methods.
{"title":"Time-Varying Moment-Tensor Analysis with Application to Buried Chemical Explosions","authors":"Jonas A. Kintner, Kenneth Michael Cleveland, James Eric Pippin, Ryan Thomas Modrak, Brent Delbridge","doi":"10.1785/0220230139","DOIUrl":"https://doi.org/10.1785/0220230139","url":null,"abstract":"Abstract The Source Physics Experiment (SPE) Phase I consisted of a series of over-buried, horizontally colocated chemical explosions at the Nevada National Security Site. Seismic waveforms from these explosions recorded at near-source accelerometers, local geophone arrays, and regional seismic stations provided a rich suite of observations suitable for resolving fine source details. To investigate the time-varying source history of the explosions, we used the frequency-domain moment-tensor inversion method described in Yang et al. (2018) with added regularization and reconstruction to suppress the nonuniqueness evident in unconstrained inversion results. The inverted moment-rate spectra are accurate within the response band of the local geophones and, in all cases, display predominately isotropic characteristics. For SPE-4Prime, SPE-5, and SPE-6, we resolve predominately isotropic moment release followed by double couple and compensated linear vector dipole (CLVD) release later in the time-varying source history. We interpret these results both in terms of absolute depth and scaled depth of burial. The apparent non-isotropic release from SPE-4Prime and SPE-5 may simply reflect increased resolving power related to improved Earth model accuracy at greater absolute depths, whereas the non-isotropic release from SPE-6 likely reflects the larger damage associated with an event at a shallower scaled depth. These results provide insight into the time-varying source characteristics of shallow explosions and motivation to study shear-wave generation by inverting for fracture, spallation, induced slip, and other temporally delayed source processes through time-varying methods.","PeriodicalId":21687,"journal":{"name":"Seismological Research Letters","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135536279","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract Bayesian network (BN) has important applications in disaster risk analysis due to its unique causal structure and probabilistic characteristics. This research begins with a detailed introduction to probabilistic seismic hazard analysis (PSHA) for China, and the utilization of BN-based modeling for seismic hazard and risk assessment. Subsequently, a comprehensive theoretical exposition of PSHA for China based on BN is presented. This includes a clear explanation of the three-level subdivision of seismic sources and the employment of the elliptical ground-motion model (GMM) in China. Regarding BN modeling, the values, conditional probabilities, and the impact of subdivisions of the nodes are carefully discussed with the assistance of a specific example from China. The advantages of BN in terms of both holistic and probabilistic computation are then demonstrated through the disaggregation of seismic hazard and various sensitivity analyses. Finally, the article concludes by summarizing its content, highlighting the advantages of BN, and outlining future work.
{"title":"Probabilistic Seismic Hazard Analysis for China Based on Bayesian Network","authors":"Chang Liu, Da-Gang Lu","doi":"10.1785/0220230159","DOIUrl":"https://doi.org/10.1785/0220230159","url":null,"abstract":"Abstract Bayesian network (BN) has important applications in disaster risk analysis due to its unique causal structure and probabilistic characteristics. This research begins with a detailed introduction to probabilistic seismic hazard analysis (PSHA) for China, and the utilization of BN-based modeling for seismic hazard and risk assessment. Subsequently, a comprehensive theoretical exposition of PSHA for China based on BN is presented. This includes a clear explanation of the three-level subdivision of seismic sources and the employment of the elliptical ground-motion model (GMM) in China. Regarding BN modeling, the values, conditional probabilities, and the impact of subdivisions of the nodes are carefully discussed with the assistance of a specific example from China. The advantages of BN in terms of both holistic and probabilistic computation are then demonstrated through the disaggregation of seismic hazard and various sensitivity analyses. Finally, the article concludes by summarizing its content, highlighting the advantages of BN, and outlining future work.","PeriodicalId":21687,"journal":{"name":"Seismological Research Letters","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135859632","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Dezheng Zhao, Chunyan Qu, Roland Bürgmann, Xinjian Shan
Abstract Long-term fault growth involves the evolution of fault zone architecture, structural maturity, and physical properties. Accurate characterization of these features is essential for improving the understanding of fault mechanics and earthquake hazards. Here, we integrate relocated aftershocks (Wang, Fang, et al., 2021), optical satellite imagery (Li et al., 2023), and field measurements (Yuan et al., 2022) to study the aftershock zone thickness and decay, coseismic surface strain, off-fault deformation, and the buried shallow fault slip of the 2021 Mw 7.4 Maduo earthquake, which occurred on an immature fault based on the total cumulative displacement of 4–5 km. We comprehensively characterize the deep, shallow, and surface fault zone deformation and link the observed variations of kinematic features to the structural maturity of the fault zone structure. Our study provides a macroscopic description of the fault zone deformation and their patterns across earthquake ruptures for the Maduo earthquake, and may have broader implications for the continental immature faults.
断裂的长期发育过程涉及断裂带构型、构造成熟度和物理性质的演化。准确地描述这些特征对于提高对断层力学和地震危险性的认识至关重要。本文基于4-5 km的累计总位移，综合重新定位余震(Wang, Fang, et, 2021)、光学卫星图像(Li et al.， 2023)和现场测量(Yuan et al.， 2022)，研究了发生在未成熟断层上的2021 Mw 7.4级玛多地震的余震带厚度和衰减、同震地表应变、断层外变形和深埋浅层断层滑动。综合刻画了深层、浅层和地表断裂带的变形特征，并将观测到的运动特征变化与断裂带构造的成熟度联系起来。我们的研究提供了玛多地震断裂带变形及其在地震破裂中的宏观描述，并可能对大陆未成熟断层有更广泛的启示。
{"title":"Characterizing Deep, Shallow, and Surface Fault Zone Deformation of the 2021 Mw 7.4 Maduo, China, Earthquake","authors":"Dezheng Zhao, Chunyan Qu, Roland Bürgmann, Xinjian Shan","doi":"10.1785/0220230115","DOIUrl":"https://doi.org/10.1785/0220230115","url":null,"abstract":"Abstract Long-term fault growth involves the evolution of fault zone architecture, structural maturity, and physical properties. Accurate characterization of these features is essential for improving the understanding of fault mechanics and earthquake hazards. Here, we integrate relocated aftershocks (Wang, Fang, et al., 2021), optical satellite imagery (Li et al., 2023), and field measurements (Yuan et al., 2022) to study the aftershock zone thickness and decay, coseismic surface strain, off-fault deformation, and the buried shallow fault slip of the 2021 Mw 7.4 Maduo earthquake, which occurred on an immature fault based on the total cumulative displacement of 4–5 km. We comprehensively characterize the deep, shallow, and surface fault zone deformation and link the observed variations of kinematic features to the structural maturity of the fault zone structure. Our study provides a macroscopic description of the fault zone deformation and their patterns across earthquake ruptures for the Maduo earthquake, and may have broader implications for the continental immature faults.","PeriodicalId":21687,"journal":{"name":"Seismological Research Letters","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135858702","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Nicola J. Litchfield, Jade Humphrey, Regine Morgenstern, Robert M. Langridge, Genevieve L. Coffey, Russ J. Van Dissen
Abstract Site-specific paleoseismic data are key datasets underpinning the parameterization of large (Mw∼7+) earthquakes on faults in seismic hazard models. For the New Zealand National Seismic Hazard Model 2022 Revision Project (NZ NSHM 2022), a new database, the NZ Paleoseismic Site Database (NZ PSDB), was developed that contains paleoseismic (slip rate, earthquake timings, recurrence interval [RI], and single-event displacement [SED]) data for crustal (upper plate) active faults. The first edition version 1.0 (v.1.0) was modeled on datasets underpinning the Third Uniform California Earthquake Rupture Forecast (UCERF3) and builds on and significantly improves previous NZ compilations. Key improvements include documentation of the data underlying these parameters, such as offset measurements and ages for slip rate, and assignment of quality rankings for key attributes. The NZ PSDB v.1.0 contains 2811 records, subdivided into slip rate (871), earthquake timings (953), and SED (987); the earthquake timings dataset also includes 320 last event and 98 RI records. Because of time constraints, the most effort went into compiling the slip-rate records, in priority from highest to lowest slip rates, and the least amount of time was spent on the SED dataset, prioritizing records from historical earthquakes. The compilation also aimed to obtain as much geographical spread as possible, but the records only lie on a relatively small (maximum, 24%) number of faults and fault sections in the NZ Community Fault Model v.1.0. The most significant spatial gaps are offshore and in the southern and western South Island. The NZ PSDB v.1.0 contains both published and unpublished data, and many sites were relocated using high-resolution basemaps. However, radiocarbon ages were not recalibrated using a consistent calibration curve. Developing a process to efficiently recalibrate radiocarbon ages, as well as filling key data gaps, are current focuses of work toward v.2.0.
{"title":"The New Zealand Paleoseismic Site Database, Version 1.0","authors":"Nicola J. Litchfield, Jade Humphrey, Regine Morgenstern, Robert M. Langridge, Genevieve L. Coffey, Russ J. Van Dissen","doi":"10.1785/0220230150","DOIUrl":"https://doi.org/10.1785/0220230150","url":null,"abstract":"Abstract Site-specific paleoseismic data are key datasets underpinning the parameterization of large (Mw∼7+) earthquakes on faults in seismic hazard models. For the New Zealand National Seismic Hazard Model 2022 Revision Project (NZ NSHM 2022), a new database, the NZ Paleoseismic Site Database (NZ PSDB), was developed that contains paleoseismic (slip rate, earthquake timings, recurrence interval [RI], and single-event displacement [SED]) data for crustal (upper plate) active faults. The first edition version 1.0 (v.1.0) was modeled on datasets underpinning the Third Uniform California Earthquake Rupture Forecast (UCERF3) and builds on and significantly improves previous NZ compilations. Key improvements include documentation of the data underlying these parameters, such as offset measurements and ages for slip rate, and assignment of quality rankings for key attributes. The NZ PSDB v.1.0 contains 2811 records, subdivided into slip rate (871), earthquake timings (953), and SED (987); the earthquake timings dataset also includes 320 last event and 98 RI records. Because of time constraints, the most effort went into compiling the slip-rate records, in priority from highest to lowest slip rates, and the least amount of time was spent on the SED dataset, prioritizing records from historical earthquakes. The compilation also aimed to obtain as much geographical spread as possible, but the records only lie on a relatively small (maximum, 24%) number of faults and fault sections in the NZ Community Fault Model v.1.0. The most significant spatial gaps are offshore and in the southern and western South Island. The NZ PSDB v.1.0 contains both published and unpublished data, and many sites were relocated using high-resolution basemaps. However, radiocarbon ages were not recalibrated using a consistent calibration curve. Developing a process to efficiently recalibrate radiocarbon ages, as well as filling key data gaps, are current focuses of work toward v.2.0.","PeriodicalId":21687,"journal":{"name":"Seismological Research Letters","volume":"43 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135768722","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Chris H. Cramer, Roy B. Van Arsdale, David Arellano, Shahram Pezeshk, Stephen P. Horton, Taylor Weathers, Nima Nazemi, Hamed Tohidi, Renee Reichenbacher, Valarie Harrison, Roshan R. Bhattarai, Mohsen Akhani, Karim Bouzeid, Gary L. Patterson
Abstract A five-year seismic and liquefaction hazard mapping project for five western Tennessee counties began in 2017 and supported natural hazard mitigation efforts in Lake, Dyer, Lauderdale, Tipton, and Madison counties. Additional geological, geotechnical, and geophysical information has been gathered in all five counties to improve the base northern Mississippi Embayment hazard maps of Dhar and Cramer (2017). Information gathered includes additional geological and geotechnical subsurface exploration logs, water table level data collection, new measurements of shallow shear-wave velocity (VS) profiles, and the compilation of existing VS profiles in and around the counties. Improvements have been made in the 3D geological model, water table model, the geotechnical liquefaction probability curves, and the VS correlation with lithology model for these counties. The resulting updated soil response amplification distributions on a 0.5 km grid were combined with the 2014 U.S. Geological Survey seismic hazard model (Petersen et al., 2014) earthquake sources and attenuation models to add the effect of local geology for Lake, Dyer, Lauderdale, Tipton, and Madison Counties. The resulting products are similar to the Memphis and Shelby County urban seismic hazard maps recently updated by Cramer, Dhar, and Arellano (2018). Generally, the effect of local geology is to reduce seismic hazard at short periods and increase it at long periods. Liquefaction hazard is high only in the alluvial lowlands, but not in the loess covered uplands.
2017年，一项针对田纳西州西部五个县的为期五年的地震和液化灾害测绘项目启动，为莱克、代尔、劳德代尔、蒂普顿和麦迪逊县的自然灾害减灾工作提供了支持。在所有五个县收集了额外的地质、岩土工程和地球物理信息，以改进Dhar和Cramer的密西西比北部基地爆炸物危险地图(2017年)。收集的信息包括额外的地质和岩土工程地下勘探日志，地下水位数据收集，浅层横波速度(VS)剖面的新测量，以及县内及周边现有横波速度剖面的汇编。对这些县的三维地质模型、地下水位模型、岩土液化概率曲线以及与岩性模型的VS相关性进行了改进。将得到的0.5 km网格上更新的土壤响应放大分布与2014年美国地质调查局地震灾害模型(Petersen et al.， 2014)的震源和衰减模型相结合，以增加当地地质对Lake、Dyer、Lauderdale、Tipton和Madison县的影响。最终的产品类似于克莱默、达尔和阿雷拉诺最近更新的孟菲斯和谢尔比县城市地震危险地图(2018年)。一般来说，局部地质的作用是在短时间内减少地震危险性，在长时间内增加地震危险性。只有冲积低地液化危险性高，黄土覆盖高地液化危险性低。
{"title":"Seismic and Liquefaction Hazard Maps for Five Western Tennessee Counties","authors":"Chris H. Cramer, Roy B. Van Arsdale, David Arellano, Shahram Pezeshk, Stephen P. Horton, Taylor Weathers, Nima Nazemi, Hamed Tohidi, Renee Reichenbacher, Valarie Harrison, Roshan R. Bhattarai, Mohsen Akhani, Karim Bouzeid, Gary L. Patterson","doi":"10.1785/0220230036","DOIUrl":"https://doi.org/10.1785/0220230036","url":null,"abstract":"Abstract A five-year seismic and liquefaction hazard mapping project for five western Tennessee counties began in 2017 and supported natural hazard mitigation efforts in Lake, Dyer, Lauderdale, Tipton, and Madison counties. Additional geological, geotechnical, and geophysical information has been gathered in all five counties to improve the base northern Mississippi Embayment hazard maps of Dhar and Cramer (2017). Information gathered includes additional geological and geotechnical subsurface exploration logs, water table level data collection, new measurements of shallow shear-wave velocity (VS) profiles, and the compilation of existing VS profiles in and around the counties. Improvements have been made in the 3D geological model, water table model, the geotechnical liquefaction probability curves, and the VS correlation with lithology model for these counties. The resulting updated soil response amplification distributions on a 0.5 km grid were combined with the 2014 U.S. Geological Survey seismic hazard model (Petersen et al., 2014) earthquake sources and attenuation models to add the effect of local geology for Lake, Dyer, Lauderdale, Tipton, and Madison Counties. The resulting products are similar to the Memphis and Shelby County urban seismic hazard maps recently updated by Cramer, Dhar, and Arellano (2018). Generally, the effect of local geology is to reduce seismic hazard at short periods and increase it at long periods. Liquefaction hazard is high only in the alluvial lowlands, but not in the loess covered uplands.","PeriodicalId":21687,"journal":{"name":"Seismological Research Letters","volume":"81 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136100435","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract Large earthquake occurrence and the subsequent postseismic period are the most dramatic part of a seismic cycle that usually lasts months to years. However, the fault dynamics that account for the postseismic events are yet to be fully understood. Here, we use the repeating aftershock sequences (RASs) to investigate postseismic slips following the Mw 6.6 Lushan, Mw 6.5 Jiuzhaigou, Mw 6.1 Jinggu, and Mw 6.2 Ludian earthquakes in the southeastern Tibetan Plateau and find 135 RASs following the mainshocks. The RAS seismicity suggests that seismogenic faults began to creep in depth within a few hours after the Lushan, Jiuzhaigou, and Jinggu mainshocks. The deep creeps mainly follow a velocity-strengthening friction mode and decay with an Omori law p-value of ∼1. The results suggest that the combination of fault healing and geometry together controls deep fault behaviors. We develop two conceptual models to explain our observations. Our results provide new insights into spatiotemporal fault evolution after large earthquakes.
{"title":"Deep Postseismic Creep Following Large Earthquakes Revealed by Repeating Aftershocks in the Southeastern Tibetan Plateau","authors":"Shujun Liu, Chi-Chia Tang","doi":"10.1785/0220230075","DOIUrl":"https://doi.org/10.1785/0220230075","url":null,"abstract":"Abstract Large earthquake occurrence and the subsequent postseismic period are the most dramatic part of a seismic cycle that usually lasts months to years. However, the fault dynamics that account for the postseismic events are yet to be fully understood. Here, we use the repeating aftershock sequences (RASs) to investigate postseismic slips following the Mw 6.6 Lushan, Mw 6.5 Jiuzhaigou, Mw 6.1 Jinggu, and Mw 6.2 Ludian earthquakes in the southeastern Tibetan Plateau and find 135 RASs following the mainshocks. The RAS seismicity suggests that seismogenic faults began to creep in depth within a few hours after the Lushan, Jiuzhaigou, and Jinggu mainshocks. The deep creeps mainly follow a velocity-strengthening friction mode and decay with an Omori law p-value of ∼1. The results suggest that the combination of fault healing and geometry together controls deep fault behaviors. We develop two conceptual models to explain our observations. Our results provide new insights into spatiotemporal fault evolution after large earthquakes.","PeriodicalId":21687,"journal":{"name":"Seismological Research Letters","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135064054","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract Since 2003, an early focus has emerged on estimating earthquake fatalities, injuries, and financial losses. This new inquiry is not yet practiced by a majority of researchers, even though one might argue it is the most important question in seismology today. No sensitive structures like reservoir dams and nuclear power plants could be built without a detailed seismic hazard analysis specifically focused on the site. On the other hand, cities near large active faults do not have their building codes determined by rigorous and specific seismic hazard and risk analyses. This contrast is startling. It seems that where mostly money is at stake, it is mandatory to consider deterministic seismic hazard analyses for construction, whereas where mostly lives are at stake, it is not. I advocate that it should be mandatory for every major city near active faults to have the seismic hazard and risk estimated so as to put an adequate local building code and other safety measures in place. To this end, a standard procedure should be defined to assess local earthquake risk in populated areas exposed to earthquake hazards. In numerous countries, the population numbers in villages, as well as the locations and sizes of schools and hospitals, are not known, and some governments refuse to distribute this information, in spite of the fact that it would be for humanitarian purposes. Because the Open Street Map and Open Building Map begin to cover the globe, this missing information, essential for first responders in natural disasters, will become available and will contribute to preparing populations at risk to reduce the impact of unavoidable future earthquakes.
{"title":"Quantitative Earthquake Loss Estimates the New Frontier","authors":"Max Wyss","doi":"10.1785/0220230192","DOIUrl":"https://doi.org/10.1785/0220230192","url":null,"abstract":"Abstract Since 2003, an early focus has emerged on estimating earthquake fatalities, injuries, and financial losses. This new inquiry is not yet practiced by a majority of researchers, even though one might argue it is the most important question in seismology today. No sensitive structures like reservoir dams and nuclear power plants could be built without a detailed seismic hazard analysis specifically focused on the site. On the other hand, cities near large active faults do not have their building codes determined by rigorous and specific seismic hazard and risk analyses. This contrast is startling. It seems that where mostly money is at stake, it is mandatory to consider deterministic seismic hazard analyses for construction, whereas where mostly lives are at stake, it is not. I advocate that it should be mandatory for every major city near active faults to have the seismic hazard and risk estimated so as to put an adequate local building code and other safety measures in place. To this end, a standard procedure should be defined to assess local earthquake risk in populated areas exposed to earthquake hazards. In numerous countries, the population numbers in villages, as well as the locations and sizes of schools and hospitals, are not known, and some governments refuse to distribute this information, in spite of the fact that it would be for humanitarian purposes. Because the Open Street Map and Open Building Map begin to cover the globe, this missing information, essential for first responders in natural disasters, will become available and will contribute to preparing populations at risk to reduce the impact of unavoidable future earthquakes.","PeriodicalId":21687,"journal":{"name":"Seismological Research Letters","volume":"45 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134911747","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract The China Earthquake Administration has currently launched an ambitious nationwide seismicity monitoring network project that will increase the number of stations from ∼950 to 2000 for the broadband seismic stations used to compile the earthquake catalog. The new network is planned to go online by the end of 2023. For more than half of Chinese mainland, the interstation distance of the broadband seismic network will soon be smaller than 100 km, for 27% smaller than 50 km, and for 6% smaller than 25 km. Of all possible ways to characterize the higher-resolution monitoring of the frequent smaller earthquakes expected inside Chinese mainland, the completeness magnitude (Mc) remains one of the most commonly used. Using the prior model of the Bayesian magnitude of completeness method calibrated on the Chinese earthquake catalog from 1 January 2009 to 26 June 2022, we predict the spatial distribution of Mc for the new network based on the planned network configuration. If almost the entire Chinese mainland is at present covered down to Mc=3.3, this threshold will fall to Mc=2.9 in the near future. This means approximately two times more earthquakes will be recorded in the complete catalog available for statistical analysis per year (for a = 6.77 and b = 0.80 in the Gutenberg–Richter law log10N=a−b·M, in which N represents the number of events of magnitude larger than or equal to M and M≥Mc). Based on the observation that abnormal seismicity as precursors are most likely to be observed at least at three units below the mainshock magnitude, and assuming earthquakes to be potentially damaging at M ≥ 5, the new seismic network shall achieve the goal of 76% coverage for optimal seismic-based earthquake prediction research.
{"title":"Predicting the Future Performance of the Planned Seismic Network in Chinese Mainland","authors":"Jiawei Li, Arnaud Mignan, Didier Sornette, Yu Feng","doi":"10.1785/0220230102","DOIUrl":"https://doi.org/10.1785/0220230102","url":null,"abstract":"Abstract The China Earthquake Administration has currently launched an ambitious nationwide seismicity monitoring network project that will increase the number of stations from ∼950 to 2000 for the broadband seismic stations used to compile the earthquake catalog. The new network is planned to go online by the end of 2023. For more than half of Chinese mainland, the interstation distance of the broadband seismic network will soon be smaller than 100 km, for 27% smaller than 50 km, and for 6% smaller than 25 km. Of all possible ways to characterize the higher-resolution monitoring of the frequent smaller earthquakes expected inside Chinese mainland, the completeness magnitude (Mc) remains one of the most commonly used. Using the prior model of the Bayesian magnitude of completeness method calibrated on the Chinese earthquake catalog from 1 January 2009 to 26 June 2022, we predict the spatial distribution of Mc for the new network based on the planned network configuration. If almost the entire Chinese mainland is at present covered down to Mc=3.3, this threshold will fall to Mc=2.9 in the near future. This means approximately two times more earthquakes will be recorded in the complete catalog available for statistical analysis per year (for a = 6.77 and b = 0.80 in the Gutenberg–Richter law log10N=a−b·M, in which N represents the number of events of magnitude larger than or equal to M and M≥Mc). Based on the observation that abnormal seismicity as precursors are most likely to be observed at least at three units below the mainshock magnitude, and assuming earthquakes to be potentially damaging at M ≥ 5, the new seismic network shall achieve the goal of 76% coverage for optimal seismic-based earthquake prediction research.","PeriodicalId":21687,"journal":{"name":"Seismological Research Letters","volume":"361 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135736439","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Omar M. Saad, M. Sami Soliman, Yangkang Chen, Abutaleb A. Amin, H. E. Abdelhafiez
Abstract Misclassified nonearthquake seismic events like quarry blasts can contaminate the earthquake catalog. The local earthquakes sometimes have similar features as the quarry blasts, which makes manual discrimination difficult and unreliable. Thus, we propose to use the compact convolutional transformer (CCT) and capsule neural network to discriminate between earthquakes and quarry blasts. First, we extract 60 s three-channel seismograms, that is, 10 and 50 s before and after the P-wave arrival time. Then, we transform the time-series data into a time–frequency domain (scalogram) using the continuous wavelet transform. Afterward, we utilize the CCT network to extract the most significant features from the input scalograms. The capsule neural network is utilized to extract the spatial relation between the extracted features using the routing-by-agreement approach (dynamic routing). The capsule neural network extracts different digit vectors for the earthquake and the quarry blast classes, allowing a robust classification accuracy. The proposed algorithm is evaluated using the seismic dataset recorded by the Egyptian Seismic Network. The dataset is divided into 80% for training and 20% for testing. Although the dataset is unbalanced, the proposed algorithm shows promising results. The testing accuracy of the proposed algorithm is 97.31%. The precision, recall, and F1-score are 97.23%, 98.83%, and 98.02%, respectively. In addition, the proposed algorithm outperforms the traditional deep learning models, for example, convolutional neural network, ResNet, Visual Geometry Group (VGG), and AlexNet networks. Finally, the proposed method is demonstrated to enjoy a high-generalization ability through a real-time monitoring experiment.
采石场爆炸等非地震事件的错误分类可能会污染地震目录。局部地震有时具有与采石场爆炸相似的特征，这使得人工判别困难且不可靠。因此，我们建议使用紧凑卷积变压器(CCT)和胶囊神经网络来区分地震和采石场爆炸。首先，提取了纵波到达时间前后10 s和50 s的60 s三通道地震图。然后，利用连续小波变换将时间序列数据转换为时频域(尺度图)。然后，我们利用CCT网络从输入尺度图中提取最重要的特征。利用胶囊神经网络，采用协议路由方法(动态路由)提取提取特征之间的空间关系。胶囊神经网络为地震和采石场爆炸分类提取不同的数字向量，具有较好的分类精度。利用埃及地震台网记录的地震数据集对所提出的算法进行了评估。数据集分为80%用于训练，20%用于测试。虽然数据集是不平衡的，但所提出的算法显示了令人满意的结果。该算法的测试准确率为97.31%。查准率为97.23%，查全率为98.83%，f1得分为98.02%。此外，该算法优于传统的深度学习模型，如卷积神经网络、ResNet、Visual Geometry Group (VGG)和AlexNet网络。最后，通过实时监测实验验证了该方法具有较高的泛化能力。
{"title":"Capsule Neural Network Guided by Compact Convolutional Transformer for Discriminating Earthquakes from Quarry Blasts","authors":"Omar M. Saad, M. Sami Soliman, Yangkang Chen, Abutaleb A. Amin, H. E. Abdelhafiez","doi":"10.1785/0220230101","DOIUrl":"https://doi.org/10.1785/0220230101","url":null,"abstract":"Abstract Misclassified nonearthquake seismic events like quarry blasts can contaminate the earthquake catalog. The local earthquakes sometimes have similar features as the quarry blasts, which makes manual discrimination difficult and unreliable. Thus, we propose to use the compact convolutional transformer (CCT) and capsule neural network to discriminate between earthquakes and quarry blasts. First, we extract 60 s three-channel seismograms, that is, 10 and 50 s before and after the P-wave arrival time. Then, we transform the time-series data into a time–frequency domain (scalogram) using the continuous wavelet transform. Afterward, we utilize the CCT network to extract the most significant features from the input scalograms. The capsule neural network is utilized to extract the spatial relation between the extracted features using the routing-by-agreement approach (dynamic routing). The capsule neural network extracts different digit vectors for the earthquake and the quarry blast classes, allowing a robust classification accuracy. The proposed algorithm is evaluated using the seismic dataset recorded by the Egyptian Seismic Network. The dataset is divided into 80% for training and 20% for testing. Although the dataset is unbalanced, the proposed algorithm shows promising results. The testing accuracy of the proposed algorithm is 97.31%. The precision, recall, and F1-score are 97.23%, 98.83%, and 98.02%, respectively. In addition, the proposed algorithm outperforms the traditional deep learning models, for example, convolutional neural network, ResNet, Visual Geometry Group (VGG), and AlexNet networks. Finally, the proposed method is demonstrated to enjoy a high-generalization ability through a real-time monitoring experiment.","PeriodicalId":21687,"journal":{"name":"Seismological Research Letters","volume":"63 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135739711","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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