Seismic interferometry is widely used for passive subsurface investigation using seismic noise. The technique requires much storage for long noise records to suppress interferometric noise, which consists of spurious arrivals that do not correspond to the inter-receiver surface waves. Such long recordings may not be available in practice. Compressive sensing (CS), which is a wavefield reconstruction technique operating on incomplete data, may increase the availability, and reduce storage limitations of long noise time series. Using a numerical example of a linear array surrounded by sources and the Fourier basis for a sparse transform, we show that inter-receiver wavefields can be recovered at the locations where seismometers are unavailable, reducing the storage required for interferometry. We propose and develop a weighted CS algorithm that helps suppress the spurious arrivals by incorporating a priori information about the arrivals of surface waves that can be expected.
{"title":"Weighted Compressive Sensing Applied to Seismic Interferometry: Wavefield Reconstruction Using Prior Information","authors":"P. Saengduean, Roel Snieder, M. Wakin","doi":"10.1785/0220230066","DOIUrl":"https://doi.org/10.1785/0220230066","url":null,"abstract":"\u0000 Seismic interferometry is widely used for passive subsurface investigation using seismic noise. The technique requires much storage for long noise records to suppress interferometric noise, which consists of spurious arrivals that do not correspond to the inter-receiver surface waves. Such long recordings may not be available in practice. Compressive sensing (CS), which is a wavefield reconstruction technique operating on incomplete data, may increase the availability, and reduce storage limitations of long noise time series. Using a numerical example of a linear array surrounded by sources and the Fourier basis for a sparse transform, we show that inter-receiver wavefields can be recovered at the locations where seismometers are unavailable, reducing the storage required for interferometry. We propose and develop a weighted CS algorithm that helps suppress the spurious arrivals by incorporating a priori information about the arrivals of surface waves that can be expected.","PeriodicalId":508466,"journal":{"name":"Seismological Research Letters","volume":" 4","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140384035","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"The 6 February 2023 Earthquakes in Southern Türkiye: When Geoscience Meets Public Concern","authors":"Tony S. Nemer","doi":"10.1785/0220240002","DOIUrl":"https://doi.org/10.1785/0220240002","url":null,"abstract":"","PeriodicalId":508466,"journal":{"name":"Seismological Research Letters","volume":"20 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140414567","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Dapeng Zhao, Xuran Liang, G. Toyokuni, Y. Hua, Yi‐Gang Xu
Earthquakes deeper than 60 km generally occur in subducting slabs. However, on 21 September 2013 two earthquakes (M 4.8 and 3.0) occurred at ∼71 to 75 km depths in the upper mantle beneath central Wyoming in the stable North American continent, where there is no actively subducting slab at present. The cause of the two events is still unclear. Here, we present detailed 3D P-wave isotropic and anisotropic tomography down to 750 km depth under Wyoming and adjacent areas. Our result shows that the two Wyoming events took place within a high-velocity (high-V) body at 0–160 km depths, which may be part of dense continental lithosphere. Another high-V body exists at ∼300 to 500 km depths, which may reflect a remnant of the subducted Farallon slab. A significant low-velocity (low-V) zone appears at ∼200 to 300 km depths between the two high-V bodies, and the low-V zone exhibits seismic anisotropy that VP is greater in the vertical direction than that in the horizontal direction. The low-V zone may include ascending fluids from dehydration of the subducted slab remnant, which was promoted by the nearby hot Yellowstone plume. It is highly possible that the ascending fluids induced the 2013 Wyoming upper-mantle earthquakes.
{"title":"Cause of Enigmatic Upper-Mantle Earthquakes in Central Wyoming","authors":"Dapeng Zhao, Xuran Liang, G. Toyokuni, Y. Hua, Yi‐Gang Xu","doi":"10.1785/0220230333","DOIUrl":"https://doi.org/10.1785/0220230333","url":null,"abstract":"\u0000 Earthquakes deeper than 60 km generally occur in subducting slabs. However, on 21 September 2013 two earthquakes (M 4.8 and 3.0) occurred at ∼71 to 75 km depths in the upper mantle beneath central Wyoming in the stable North American continent, where there is no actively subducting slab at present. The cause of the two events is still unclear. Here, we present detailed 3D P-wave isotropic and anisotropic tomography down to 750 km depth under Wyoming and adjacent areas. Our result shows that the two Wyoming events took place within a high-velocity (high-V) body at 0–160 km depths, which may be part of dense continental lithosphere. Another high-V body exists at ∼300 to 500 km depths, which may reflect a remnant of the subducted Farallon slab. A significant low-velocity (low-V) zone appears at ∼200 to 300 km depths between the two high-V bodies, and the low-V zone exhibits seismic anisotropy that VP is greater in the vertical direction than that in the horizontal direction. The low-V zone may include ascending fluids from dehydration of the subducted slab remnant, which was promoted by the nearby hot Yellowstone plume. It is highly possible that the ascending fluids induced the 2013 Wyoming upper-mantle earthquakes.","PeriodicalId":508466,"journal":{"name":"Seismological Research Letters","volume":"83 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140414360","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
R. Maguire, Brandon Schmandt, Ruijia Wang, Qingkai Kong, Pedro Sanchez
Although accurately classifying signals from earthquakes and explosions at local distance (<250 km) remains an important task for seismic network operations, the growing volume of available seismic data presents a challenge for analysts using traditional source discrimination techniques. In recent years, deep-learning models have proven effective at discriminating between low-magnitude earthquakes and explosions measured at local distances, but it is not clear how well these models are capable of generalizing across different geological settings. To address the issue of generalization between regions, we train deep-learning models (convolutional neural networks [CNNs]) on time–frequency representations (scalograms) of three-component earthquake and explosion signals from eight different regions in the continental United States. We explore scenarios where models are trained on data from all regions, individual regions, or all but one region. We find that although CNN models trained on individual regions do not necessarily generalize well across different settings, models trained on multiple regions that include diverse path coverage generalize to new regions, with station-level accuracy of up to 90% or more for data sets from unseen regions. In general, CNN-based discrimination models significantly outperform models based on uncorrected P/S ratio (measured in the 10–18 Hz frequency band), even when CNN models are tested on data from entirely unseen regions.
{"title":"Generalization of Deep-Learning Models for Classification of Local Distance Earthquakes and Explosions across Various Geologic Settings","authors":"R. Maguire, Brandon Schmandt, Ruijia Wang, Qingkai Kong, Pedro Sanchez","doi":"10.1785/0220230267","DOIUrl":"https://doi.org/10.1785/0220230267","url":null,"abstract":"\u0000 Although accurately classifying signals from earthquakes and explosions at local distance (<250 km) remains an important task for seismic network operations, the growing volume of available seismic data presents a challenge for analysts using traditional source discrimination techniques. In recent years, deep-learning models have proven effective at discriminating between low-magnitude earthquakes and explosions measured at local distances, but it is not clear how well these models are capable of generalizing across different geological settings. To address the issue of generalization between regions, we train deep-learning models (convolutional neural networks [CNNs]) on time–frequency representations (scalograms) of three-component earthquake and explosion signals from eight different regions in the continental United States. We explore scenarios where models are trained on data from all regions, individual regions, or all but one region. We find that although CNN models trained on individual regions do not necessarily generalize well across different settings, models trained on multiple regions that include diverse path coverage generalize to new regions, with station-level accuracy of up to 90% or more for data sets from unseen regions. In general, CNN-based discrimination models significantly outperform models based on uncorrected P/S ratio (measured in the 10–18 Hz frequency band), even when CNN models are tested on data from entirely unseen regions.","PeriodicalId":508466,"journal":{"name":"Seismological Research Letters","volume":"4 36","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140410429","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Internal structures of the Moon are key to understanding the origin and evolution of the Earth–Moon system and other planets. The Apollo Passive Seismic Experiment detected thousands of lunar seismic events and vastly improved our understanding of the Moon’s interior. However, some critical questions like the state and composition of the core remain unsolved largely due to the sparsity of the Apollo seismic stations and the strong scattering of seismic waves in the top layer of the Moon. In this study, we propose the concept of a fiber seismic network on the Moon and discuss its potential in overcoming the challenges in imaging deep Moon structures. As an emerging technique, distributed acoustic sensing (DAS) can provide a cost-efficient solution for large-aperture and dense seismic network deployment in harsh environments. We compute lunar synthetic seismograms and evaluate the performance of DAS arrays of different configurations in retrieving the hidden core reflected seismic phase ScS from the strong scattered waves. We find that, compared to a sparse conventional seismic network, a fiber seismic network using tens of kilometers of cable can dramatically increase the chance of observing clear ScS by array stacking. Our results indicate that DAS could provide new opportunities for the future lunar seismic surveys, but more efforts and further evaluations are required to develop a space-proof DAS.
月球内部结构是了解地月系统和其他行星起源与演化的关键。阿波罗被动地震实验探测到了数以千计的月球地震事件，极大地提高了我们对月球内部的认识。然而，由于阿波罗地震台站的稀少和地震波在月球表层的强烈散射，一些关键问题（如内核的状态和组成）仍未得到解决。在本研究中，我们提出了月球光纤地震网络的概念，并讨论了其在克服月球深层结构成像挑战方面的潜力。作为一种新兴技术，分布式声学传感（DAS）可为在恶劣环境中部署大孔径、高密度的地震网络提供经济高效的解决方案。我们计算了月球合成地震图，并评估了不同配置的 DAS 阵列在从强散射波中检索隐藏核心反射地震相位 ScS 方面的性能。我们发现，与稀疏的传统地震台网相比，使用数十公里电缆的光纤地震台网可通过阵列堆叠显著提高观测到清晰 ScS 的几率。我们的研究结果表明，DAS 可以为未来的月球地震勘测提供新的机遇，但要开发出一种不受空间影响的 DAS，还需要更多的努力和进一步的评估。
{"title":"Fiber Seismic Network on the Moon","authors":"Wenbo Wu, Z. Zhan, M. Panning, Andrew Klesh","doi":"10.1785/0220230067","DOIUrl":"https://doi.org/10.1785/0220230067","url":null,"abstract":"\u0000 Internal structures of the Moon are key to understanding the origin and evolution of the Earth–Moon system and other planets. The Apollo Passive Seismic Experiment detected thousands of lunar seismic events and vastly improved our understanding of the Moon’s interior. However, some critical questions like the state and composition of the core remain unsolved largely due to the sparsity of the Apollo seismic stations and the strong scattering of seismic waves in the top layer of the Moon. In this study, we propose the concept of a fiber seismic network on the Moon and discuss its potential in overcoming the challenges in imaging deep Moon structures. As an emerging technique, distributed acoustic sensing (DAS) can provide a cost-efficient solution for large-aperture and dense seismic network deployment in harsh environments. We compute lunar synthetic seismograms and evaluate the performance of DAS arrays of different configurations in retrieving the hidden core reflected seismic phase ScS from the strong scattered waves. We find that, compared to a sparse conventional seismic network, a fiber seismic network using tens of kilometers of cable can dramatically increase the chance of observing clear ScS by array stacking. Our results indicate that DAS could provide new opportunities for the future lunar seismic surveys, but more efforts and further evaluations are required to develop a space-proof DAS.","PeriodicalId":508466,"journal":{"name":"Seismological Research Letters","volume":"62 5","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140419639","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yongbo Li, J. Zhuang, Shi Chen, Yicun Guo, Z. Xiong
This study proposes a hypocentral version of the spherical epidemic-type aftershock sequence (ETAS) model by incorporating hypocentral depth information into the spherical ETAS model and applies it to earthquake data from the Alaska-Aleutian area. We validate the model using the stochastic reconstruction techniques and illustrate the rationale behind selecting the spatial probability density function. Subsequently, we estimate the 3D spatial variations of the background and offspring seismicity in the study region, revealing that the majority of clusters are located in shallow regions. We also identify an apparent temporal change in the background seismicity caused by artificial effects. Compared with the 3D-ETAS and spherical version of the epidemic-type aftershock sequence (SETAS) models, the new 3D-SETAS model provides a better description of 3D seismicity in high-latitude regions globally.
{"title":"A 3D Spherical ETAS Model: A Case Study in the Alaska-Aleutian Region","authors":"Yongbo Li, J. Zhuang, Shi Chen, Yicun Guo, Z. Xiong","doi":"10.1785/0220230440","DOIUrl":"https://doi.org/10.1785/0220230440","url":null,"abstract":"\u0000 This study proposes a hypocentral version of the spherical epidemic-type aftershock sequence (ETAS) model by incorporating hypocentral depth information into the spherical ETAS model and applies it to earthquake data from the Alaska-Aleutian area. We validate the model using the stochastic reconstruction techniques and illustrate the rationale behind selecting the spatial probability density function. Subsequently, we estimate the 3D spatial variations of the background and offspring seismicity in the study region, revealing that the majority of clusters are located in shallow regions. We also identify an apparent temporal change in the background seismicity caused by artificial effects. Compared with the 3D-ETAS and spherical version of the epidemic-type aftershock sequence (SETAS) models, the new 3D-SETAS model provides a better description of 3D seismicity in high-latitude regions globally.","PeriodicalId":508466,"journal":{"name":"Seismological Research Letters","volume":"121 5","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140423675","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In land-based seismology, modern automatic earthquake detection and phase picking algorithms have already proven to outperform classic approaches, resulting in more complete catalogs when only taking a fraction of the time needed for classic methods. For marine-based seismology, similar advances have not been made yet. For ocean-bottom seismometer (OBS) data, additional challenges arise, such as a lower signal-to-noise ratio and fewer labeled data sets available for training deep-learning models. However, the performance of available deep-learning models has not yet been extensively tested on marine-based data sets. Here, we apply three different modern event detection and phase picking approaches to an ∼12 month local OBS data set and compare the resulting earthquake catalogs and location results. In addition, we evaluate their performance by comparing different subcatalogs of manually detected events and visually revised picks to their automatic counterparts. The results show that seismicity patterns from automatically compiled catalogs are comparable to a manually revised catalog after applying strict location quality control criteria. However, the number of such well-constrained events varies between the approaches and catalog completeness cannot be reliably determined. We find that PhaseNet is more suitable for local OBS networks compared with EQTransformer and propose a pick-independent event detection approach, such as Lassie, as the preferred choice for an initial event catalog compilation. Depending on the aim of the study, different schemes of manual repicking should be applied because the automatic picks are not yet reliable enough for developing a velocity model or interpreting small-scale seismicity patterns.
{"title":"A Practical Approach to Automatic Earthquake Catalog Compilation in Local OBS Networks Using Deep-Learning and Network-Based Algorithms","authors":"Matthias Pilot, Vera Schlindwein","doi":"10.1785/0220230182","DOIUrl":"https://doi.org/10.1785/0220230182","url":null,"abstract":"\u0000 In land-based seismology, modern automatic earthquake detection and phase picking algorithms have already proven to outperform classic approaches, resulting in more complete catalogs when only taking a fraction of the time needed for classic methods. For marine-based seismology, similar advances have not been made yet. For ocean-bottom seismometer (OBS) data, additional challenges arise, such as a lower signal-to-noise ratio and fewer labeled data sets available for training deep-learning models. However, the performance of available deep-learning models has not yet been extensively tested on marine-based data sets. Here, we apply three different modern event detection and phase picking approaches to an ∼12 month local OBS data set and compare the resulting earthquake catalogs and location results. In addition, we evaluate their performance by comparing different subcatalogs of manually detected events and visually revised picks to their automatic counterparts. The results show that seismicity patterns from automatically compiled catalogs are comparable to a manually revised catalog after applying strict location quality control criteria. However, the number of such well-constrained events varies between the approaches and catalog completeness cannot be reliably determined. We find that PhaseNet is more suitable for local OBS networks compared with EQTransformer and propose a pick-independent event detection approach, such as Lassie, as the preferred choice for an initial event catalog compilation. Depending on the aim of the study, different schemes of manual repicking should be applied because the automatic picks are not yet reliable enough for developing a velocity model or interpreting small-scale seismicity patterns.","PeriodicalId":508466,"journal":{"name":"Seismological Research Letters","volume":"35 12","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140437322","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Zhaoxuan Guan, Yongge Wan, Shaohua Huang, Gan Feng
The 2021 Maduo earthquake sequence occurred on the Jiangcuo fault zone in Qinghai, China. However, the earthquake sequence did not occur along a straight fault. Aftershocks in the southeast section deflected the aftershocks in the southeast section to the east, when the aftershocks in the northwest section bifurcated. To investigate the relationship between these eastward deflections, aftershock bifurcations, and fault activity, 150 focal mechanism solutions of the Maduo earthquake sequence are collected and processed, and then the stress fields in the subregion and whole region are subsequently determined by partitioning the sliding window from southeast to northwest. The results show that the overall tectonic stress field of the Maduo earthquake sequence exhibits northeast–southwest compression and northwest–southeast extension due to the northward compression of the Indian plate, causing rupture of the Kunlunshankou-Jiangcuo fault, which straightened the curved Maduo-Gander fault. The stress field at the deflection of the southeastern section of the source area differs significantly from the overall stress field. The plunge angle of the extensional stress axis in the southeastern deflection area is close to vertical, which is speculated to be due to the effect of the crack tip and the adjustment of local stress after the earthquake. The extensional stress axis at the bifurcated distribution of aftershocks in the northwestern section of the source area is slightly greater than of the overall stress field, indicating that the activation of the bifurcated hidden fault was triggered by the high rupture intensity and the adjustment of local stress. The reactivation of the hidden bifurcated fault results in local stress and causes decreasing seismicity west of the bifurcation area.
{"title":"Study on the Heterogeneity of the Stress Field in the Maduo Earthquake Fault Zone","authors":"Zhaoxuan Guan, Yongge Wan, Shaohua Huang, Gan Feng","doi":"10.1785/0220230350","DOIUrl":"https://doi.org/10.1785/0220230350","url":null,"abstract":"\u0000 The 2021 Maduo earthquake sequence occurred on the Jiangcuo fault zone in Qinghai, China. However, the earthquake sequence did not occur along a straight fault. Aftershocks in the southeast section deflected the aftershocks in the southeast section to the east, when the aftershocks in the northwest section bifurcated. To investigate the relationship between these eastward deflections, aftershock bifurcations, and fault activity, 150 focal mechanism solutions of the Maduo earthquake sequence are collected and processed, and then the stress fields in the subregion and whole region are subsequently determined by partitioning the sliding window from southeast to northwest. The results show that the overall tectonic stress field of the Maduo earthquake sequence exhibits northeast–southwest compression and northwest–southeast extension due to the northward compression of the Indian plate, causing rupture of the Kunlunshankou-Jiangcuo fault, which straightened the curved Maduo-Gander fault. The stress field at the deflection of the southeastern section of the source area differs significantly from the overall stress field. The plunge angle of the extensional stress axis in the southeastern deflection area is close to vertical, which is speculated to be due to the effect of the crack tip and the adjustment of local stress after the earthquake. The extensional stress axis at the bifurcated distribution of aftershocks in the northwestern section of the source area is slightly greater than of the overall stress field, indicating that the activation of the bifurcated hidden fault was triggered by the high rupture intensity and the adjustment of local stress. The reactivation of the hidden bifurcated fault results in local stress and causes decreasing seismicity west of the bifurcation area.","PeriodicalId":508466,"journal":{"name":"Seismological Research Letters","volume":"242 4","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140443432","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In a recent opinion piece Albarello and Paolucci (2023; hereafter, AP23) provide their view as members of the past Seismic Group of the Commissione Grandi Rischi (CGR-SRS) in Italy, which represents the main scientific consultant for Italian Civil Protection, about the difficulty using probabilistic seismic hazard analysis (PSHA) models for building code purposes. Here, we refer to this specific kind of PSHA modeling as National Seismic Hazard Model (NSHM). We agree with AP23 that the topic is of great and general importance, and here we aim at contributing to this discussion by offering our perspective on two points that are at the heart of the matter, concluding that AP23 is misguided in how to deal with them. First, we assert that the credibility of an NSHM has to be rooted only in the use of the best available science, which includes a rigorous testing phase with observations, independent from the consequences in terms of risk. (PSHA deals with what it is.) Second, we claim that the difficulties in accepting a new NSHM with some major changes with respect to the previous model are mostly due to too rigid building code procedures that do not account for the epistemic uncertainty in the hazard estimates.
{"title":"PSHA: Does It Deal with What It Is or What We Want It to Be?","authors":"W. Marzocchi, C. Meletti","doi":"10.1785/0220230418","DOIUrl":"https://doi.org/10.1785/0220230418","url":null,"abstract":"\u0000 In a recent opinion piece Albarello and Paolucci (2023; hereafter, AP23) provide their view as members of the past Seismic Group of the Commissione Grandi Rischi (CGR-SRS) in Italy, which represents the main scientific consultant for Italian Civil Protection, about the difficulty using probabilistic seismic hazard analysis (PSHA) models for building code purposes. Here, we refer to this specific kind of PSHA modeling as National Seismic Hazard Model (NSHM). We agree with AP23 that the topic is of great and general importance, and here we aim at contributing to this discussion by offering our perspective on two points that are at the heart of the matter, concluding that AP23 is misguided in how to deal with them. First, we assert that the credibility of an NSHM has to be rooted only in the use of the best available science, which includes a rigorous testing phase with observations, independent from the consequences in terms of risk. (PSHA deals with what it is.) Second, we claim that the difficulties in accepting a new NSHM with some major changes with respect to the previous model are mostly due to too rigid building code procedures that do not account for the epistemic uncertainty in the hazard estimates.","PeriodicalId":508466,"journal":{"name":"Seismological Research Letters","volume":"9 5","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140443260","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Rong Zou, Junxiang Wang, Xinyu Zhao, Zhiwei Fang, Kejie Chen, R. Fang, Qi Wang
We use surface deformation measurements, including Interferometric Synthetic Aperture Radar data acquired by the Sentinel-1A satellites and Global Navigation Satellite System observations, to invert the fault geometry and coseismic slip distribution of the 2022 Mw 6.6 earthquake in Sichuan, China. The dip of the best-fitting model is 68°. The rupture of the 2022 Luding earthquake is dominated by northwest strike-slip movement, mainly concentrated over a length of about 20 km above a depth of 15 km. The maximum slip is at approximately 4 km depth with the maximum displacement of about 2.1 m. The results indicate that the 2022 Luding earthquake ruptured the shallow layer of the seismic zone. The slip distribution indicates that the Moxi–Shimian fault segment is fully locked from the surface down to 15 km, which is consistent with the estimated locking depth. Based on the Coulomb stress analysis and considering the strong locking state of the Anninghe fault, more attention should be paid to the possibility of earthquakes in the Anninghe fault.
{"title":"Slip Model of the 2022 Mw 6.6 Luding Earthquake from Inversion of GNSS and InSAR with Sentinel-1","authors":"Rong Zou, Junxiang Wang, Xinyu Zhao, Zhiwei Fang, Kejie Chen, R. Fang, Qi Wang","doi":"10.1785/0220230113","DOIUrl":"https://doi.org/10.1785/0220230113","url":null,"abstract":"\u0000 We use surface deformation measurements, including Interferometric Synthetic Aperture Radar data acquired by the Sentinel-1A satellites and Global Navigation Satellite System observations, to invert the fault geometry and coseismic slip distribution of the 2022 Mw 6.6 earthquake in Sichuan, China. The dip of the best-fitting model is 68°. The rupture of the 2022 Luding earthquake is dominated by northwest strike-slip movement, mainly concentrated over a length of about 20 km above a depth of 15 km. The maximum slip is at approximately 4 km depth with the maximum displacement of about 2.1 m. The results indicate that the 2022 Luding earthquake ruptured the shallow layer of the seismic zone. The slip distribution indicates that the Moxi–Shimian fault segment is fully locked from the surface down to 15 km, which is consistent with the estimated locking depth. Based on the Coulomb stress analysis and considering the strong locking state of the Anninghe fault, more attention should be paid to the possibility of earthquakes in the Anninghe fault.","PeriodicalId":508466,"journal":{"name":"Seismological Research Letters","volume":"140 5","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140484536","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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