Pub Date : 2024-03-07DOI: 10.1177/87552930241231925
Naveen Senthil, Ting Lin
Limited availability of recorded ground motions poses a challenge for reliable probabilistic seismic-hazard analysis (PSHA), even in highly seismic regions like the Western United States. Stochastic ground motions are commonly employed to address this challenge. However, the stochastic ground motion models (GMMs) may not consistently generate ground motions compatible with the site hazard due to their calibration using global data, failing to capture site-specific characteristics adequately. In the absence of recorded motions, physics-informed simulations provide a viable alternative but are deterministic with limitations of their own that makes them challenging to support PSHA. This article introduces a Bayesian framework that combines prior knowledge from a stochastic GMM, calibrated with global data, with site-specific data obtained from deterministic physics-informed simulations. The proposed framework utilizes the Rezaeian–Der Kiureghian (2010) model as the stochastic GMM and incorporates site-specific data from the CyberShake 15.12 study. By updating the mean and variance of the predictive relationships, along with the marginal distribution of the model parameters, through Bayesian inference, this framework allows for the simulation of site-specific ground motions consistent with the site characteristics. The statistics of peak ground acceleration distributions, as well as both the median and variability of the elastic response spectra, obtained from the calibrated stochastic GMM, demonstrate consistency with those derived using GMMs based on the Next Generation Attenuation (NGA) database.
{"title":"Site-specific stochastic ground motion model utilizing deterministic physics-informed simulations: A Bayesian approach","authors":"Naveen Senthil, Ting Lin","doi":"10.1177/87552930241231925","DOIUrl":"https://doi.org/10.1177/87552930241231925","url":null,"abstract":"Limited availability of recorded ground motions poses a challenge for reliable probabilistic seismic-hazard analysis (PSHA), even in highly seismic regions like the Western United States. Stochastic ground motions are commonly employed to address this challenge. However, the stochastic ground motion models (GMMs) may not consistently generate ground motions compatible with the site hazard due to their calibration using global data, failing to capture site-specific characteristics adequately. In the absence of recorded motions, physics-informed simulations provide a viable alternative but are deterministic with limitations of their own that makes them challenging to support PSHA. This article introduces a Bayesian framework that combines prior knowledge from a stochastic GMM, calibrated with global data, with site-specific data obtained from deterministic physics-informed simulations. The proposed framework utilizes the Rezaeian–Der Kiureghian (2010) model as the stochastic GMM and incorporates site-specific data from the CyberShake 15.12 study. By updating the mean and variance of the predictive relationships, along with the marginal distribution of the model parameters, through Bayesian inference, this framework allows for the simulation of site-specific ground motions consistent with the site characteristics. The statistics of peak ground acceleration distributions, as well as both the median and variability of the elastic response spectra, obtained from the calibrated stochastic GMM, demonstrate consistency with those derived using GMMs based on the Next Generation Attenuation (NGA) database.","PeriodicalId":11392,"journal":{"name":"Earthquake Spectra","volume":"281 1","pages":""},"PeriodicalIF":5.0,"publicationDate":"2024-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140075391","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-03-07DOI: 10.1177/87552930241232994
Diane M Moug, Jonathan D Bray, Patrick Bassal, Jorge Macedo, Kristin Ulmer, K Önder Cetin, Sena Begüm Kendır, Arda Şahin, Cody Arnold, Murat Bikçe
Significant and widespread liquefaction occurred in İskenderun during the 2023 moment magnitude (Mw) 7.8 Kahramanmaraş earthquake. Liquefaction effects on buildings were observed in several areas of İskenderun, predominantly in areas of reclaimed land and near historic shorelines. Liquefaction-induced building settlements were particularly concentrated in the Çay District, which is almost entirely reclaimed land. Liquefaction-induced ground and building settlements were either marginal or not apparent in areas away from the historical shorelines. Building settlement and ground deformation were documented at 26 buildings in İskenderun through lidar scans and laser-level hand measurements. Liquefaction-induced building settlements ranged from 0 to 740 mm. Building-ground interactions were evident from hogging ground deformations, including cases where buildings deformed nearby ground and damaged nearby buildings, and sagging buildings. Historic land development affected the spatial extent of observed liquefaction-induced building damage. Representative liquefaction-induced building settlement and building interaction case histories are discussed and key insights are shared.
{"title":"Liquefaction-induced ground and building interactions in İskenderun from the 2023 Kahramanmaraş earthquake sequence","authors":"Diane M Moug, Jonathan D Bray, Patrick Bassal, Jorge Macedo, Kristin Ulmer, K Önder Cetin, Sena Begüm Kendır, Arda Şahin, Cody Arnold, Murat Bikçe","doi":"10.1177/87552930241232994","DOIUrl":"https://doi.org/10.1177/87552930241232994","url":null,"abstract":"Significant and widespread liquefaction occurred in İskenderun during the 2023 moment magnitude (M<jats:sub>w</jats:sub>) 7.8 Kahramanmaraş earthquake. Liquefaction effects on buildings were observed in several areas of İskenderun, predominantly in areas of reclaimed land and near historic shorelines. Liquefaction-induced building settlements were particularly concentrated in the Çay District, which is almost entirely reclaimed land. Liquefaction-induced ground and building settlements were either marginal or not apparent in areas away from the historical shorelines. Building settlement and ground deformation were documented at 26 buildings in İskenderun through lidar scans and laser-level hand measurements. Liquefaction-induced building settlements ranged from 0 to 740 mm. Building-ground interactions were evident from hogging ground deformations, including cases where buildings deformed nearby ground and damaged nearby buildings, and sagging buildings. Historic land development affected the spatial extent of observed liquefaction-induced building damage. Representative liquefaction-induced building settlement and building interaction case histories are discussed and key insights are shared.","PeriodicalId":11392,"journal":{"name":"Earthquake Spectra","volume":"5 1","pages":""},"PeriodicalIF":5.0,"publicationDate":"2024-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140075493","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-03-04DOI: 10.1177/87552930241233251
Jui-Liang Lin, Che-Min Lin, Jyun-Yan Huang
Near-fault pulse-like (PL) ground motions generally transmit huge amounts of energy into structures during a relatively short period compared with non-pulse-like (NPL) ground motions. Consequently, power demand has emerged as a direct and distinctive measure for evaluating the risk that PL ground motions pose on structures. This study examines the power demands of structures subjected to ground motions recorded at 10 seismic stations in six city (or town) centers during the Mw 7.8 earthquake that hit Türkiye on 6 February 2023. The six cities (or towns), Golbasi, Kahramanmaras, Nurdagi, Osmaniye, Iskenderun, and Antakya, were the locations where an international team conducted field reconnaissance 2 weeks after the earthquake. This study first evaluates the power histories and other seismic responses of single-degree-of-freedom structures exposed to both PL and NPL ground motions. Subsequently, the power spectra of 20 horizontal ground motions recorded at the 10 stations are constructed and examined. Through these investigations, we hope to gain a better understanding of and raise awareness regarding the threats that PL ground motions pose to structures in the six cities (or towns) during the earthquake.
{"title":"Power demands of structures from the Mw 7.8 earthquake of 6 February 2023 in Türkiye","authors":"Jui-Liang Lin, Che-Min Lin, Jyun-Yan Huang","doi":"10.1177/87552930241233251","DOIUrl":"https://doi.org/10.1177/87552930241233251","url":null,"abstract":"Near-fault pulse-like (PL) ground motions generally transmit huge amounts of energy into structures during a relatively short period compared with non-pulse-like (NPL) ground motions. Consequently, power demand has emerged as a direct and distinctive measure for evaluating the risk that PL ground motions pose on structures. This study examines the power demands of structures subjected to ground motions recorded at 10 seismic stations in six city (or town) centers during the M<jats:sub>w</jats:sub> 7.8 earthquake that hit Türkiye on 6 February 2023. The six cities (or towns), Golbasi, Kahramanmaras, Nurdagi, Osmaniye, Iskenderun, and Antakya, were the locations where an international team conducted field reconnaissance 2 weeks after the earthquake. This study first evaluates the power histories and other seismic responses of single-degree-of-freedom structures exposed to both PL and NPL ground motions. Subsequently, the power spectra of 20 horizontal ground motions recorded at the 10 stations are constructed and examined. Through these investigations, we hope to gain a better understanding of and raise awareness regarding the threats that PL ground motions pose to structures in the six cities (or towns) during the earthquake.","PeriodicalId":11392,"journal":{"name":"Earthquake Spectra","volume":"53 1","pages":""},"PeriodicalIF":5.0,"publicationDate":"2024-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140034617","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-02-29DOI: 10.1177/87552930231223995
Morgan P Moschetti, Brad T Aagaard, Sean K Ahdi, Jason Altekruse, Oliver S Boyd, Arthur D Frankel, Julie Herrick, Mark D Petersen, Peter M Powers, Sanaz Rezaeian, Allison M Shumway, James A Smith, William J Stephenson, Eric M Thompson, Kyle B Withers
We update the ground-motion characterization for the 2023 National Seismic Hazard Model (NSHM) for the conterminous United States. The update includes the use of new ground-motion models (GMMs) in the Cascadia subduction zone; an adjustment to the central and eastern United States (CEUS) GMMs to reduce misfits with observed data; an updated boundary for the application of GMMs for shallow, crustal earthquakes in active tectonic regions (i.e. western United States (WUS)) and stable continental regions (i.e. CEUS); and the use of improved models for the site response of deep sedimentary basins in the WUS and CEUS. Site response updates include basin models for the California Great Valley and for the Portland and Tualatin basins, Oregon, as well as long-period basin effects from three-dimensional simulations in the Greater Los Angeles region and in the Seattle basin; in the CEUS, we introduce a broadband (0.01- to 10-s period) amplification model for the effects of the passive-margin basins of the Atlantic and Gulf Coastal Plains. In addition, we summarize progress on implementing rupture directivity models into seismic hazard models, although they are not incorporated in the 2023 NSHM. We implement the ground-motion characterization for the 2023 NSHM in the US Geological Survey’s code for probabilistic seismic hazard analysis, nshmp-haz-v2, and present the sensitivity of hazard to these changes. Hazard calculations indicate widespread effects from adjustments to the CEUS GMMs, from the incorporation of Coastal Plain amplification effects, and from the treatment of shallow-basin and out-of-basin sites in the San Francisco Bay Area and Los Angeles region, as well as locally important changes from subduction-zone GMMs, and from updated and new WUS basins.
{"title":"The 2023 US National Seismic Hazard Model: Ground-motion characterization for the conterminous United States","authors":"Morgan P Moschetti, Brad T Aagaard, Sean K Ahdi, Jason Altekruse, Oliver S Boyd, Arthur D Frankel, Julie Herrick, Mark D Petersen, Peter M Powers, Sanaz Rezaeian, Allison M Shumway, James A Smith, William J Stephenson, Eric M Thompson, Kyle B Withers","doi":"10.1177/87552930231223995","DOIUrl":"https://doi.org/10.1177/87552930231223995","url":null,"abstract":"We update the ground-motion characterization for the 2023 National Seismic Hazard Model (NSHM) for the conterminous United States. The update includes the use of new ground-motion models (GMMs) in the Cascadia subduction zone; an adjustment to the central and eastern United States (CEUS) GMMs to reduce misfits with observed data; an updated boundary for the application of GMMs for shallow, crustal earthquakes in active tectonic regions (i.e. western United States (WUS)) and stable continental regions (i.e. CEUS); and the use of improved models for the site response of deep sedimentary basins in the WUS and CEUS. Site response updates include basin models for the California Great Valley and for the Portland and Tualatin basins, Oregon, as well as long-period basin effects from three-dimensional simulations in the Greater Los Angeles region and in the Seattle basin; in the CEUS, we introduce a broadband (0.01- to 10-s period) amplification model for the effects of the passive-margin basins of the Atlantic and Gulf Coastal Plains. In addition, we summarize progress on implementing rupture directivity models into seismic hazard models, although they are not incorporated in the 2023 NSHM. We implement the ground-motion characterization for the 2023 NSHM in the US Geological Survey’s code for probabilistic seismic hazard analysis, nshmp-haz-v2, and present the sensitivity of hazard to these changes. Hazard calculations indicate widespread effects from adjustments to the CEUS GMMs, from the incorporation of Coastal Plain amplification effects, and from the treatment of shallow-basin and out-of-basin sites in the San Francisco Bay Area and Los Angeles region, as well as locally important changes from subduction-zone GMMs, and from updated and new WUS basins.","PeriodicalId":11392,"journal":{"name":"Earthquake Spectra","volume":"34 1","pages":""},"PeriodicalIF":5.0,"publicationDate":"2024-02-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140001890","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-02-28DOI: 10.1177/87552930241231935
Wenyang Zhang, Yufeng Dong, Jorge GF Crempien, Pedro Arduino, Asli Kurtulus, Ertugrul Taciroglu
One-dimensional (1D) site response analysis (SRA), which considers vertically propagating seismic waves from the bedrock to the surface, has been a common technique among geotechnical engineers to examine site-specific ground shaking. However, observations from past earthquakes and analytical studies indicate that idealizations ingrained in 1D SRA may be too severe to capture the ground truth, such as the omissions of spatial variability of soil properties, surface topography, and basin and directivity effects. Physics-based three-dimensional ground motion simulations (GMSs) can incorporate these factors and yield more reliable predictions. In this study, we utilize ground motions from 57 physics-based broadband (from 0 to 8–12 Hz) GMS for a region of Istanbul. A total of 2912 sites with experimentally measured soil profiles that are distributed over the 30 km-by-12.5 km area are also modeled as soil columns and analyzed through 1D SRA. The ground responses from 1D SRA and three-dimensional (3D) GMS are then compared for all 57 earthquake scenarios. These systematic comparisons are then used for examining model features that are correlated with variations in the ratios of various ground motion intensity measures (IMs) and for developing regression-based formulas that can be used for determining simple factors for the considered region to correctly scale (up or down) the site-specific ground motion intensities obtained from 1D SRA, including peak ground acceleration (PGA), peak ground velocity (PGV), and spectral acceleration ( Sa) values.
{"title":"A comparison of ground motions predicted through one-dimensional site response analyses and three-dimensional wave propagation simulations at regional scales","authors":"Wenyang Zhang, Yufeng Dong, Jorge GF Crempien, Pedro Arduino, Asli Kurtulus, Ertugrul Taciroglu","doi":"10.1177/87552930241231935","DOIUrl":"https://doi.org/10.1177/87552930241231935","url":null,"abstract":"One-dimensional (1D) site response analysis (SRA), which considers vertically propagating seismic waves from the bedrock to the surface, has been a common technique among geotechnical engineers to examine site-specific ground shaking. However, observations from past earthquakes and analytical studies indicate that idealizations ingrained in 1D SRA may be too severe to capture the ground truth, such as the omissions of spatial variability of soil properties, surface topography, and basin and directivity effects. Physics-based three-dimensional ground motion simulations (GMSs) can incorporate these factors and yield more reliable predictions. In this study, we utilize ground motions from 57 physics-based broadband (from 0 to 8–12 Hz) GMS for a region of Istanbul. A total of 2912 sites with experimentally measured soil profiles that are distributed over the 30 km-by-12.5 km area are also modeled as soil columns and analyzed through 1D SRA. The ground responses from 1D SRA and three-dimensional (3D) GMS are then compared for all 57 earthquake scenarios. These systematic comparisons are then used for examining model features that are correlated with variations in the ratios of various ground motion intensity measures (IMs) and for developing regression-based formulas that can be used for determining simple factors for the considered region to correctly scale (up or down) the site-specific ground motion intensities obtained from 1D SRA, including peak ground acceleration (PGA), peak ground velocity (PGV), and spectral acceleration ( S<jats:sub>a</jats:sub>) values.","PeriodicalId":11392,"journal":{"name":"Earthquake Spectra","volume":"170 1","pages":""},"PeriodicalIF":5.0,"publicationDate":"2024-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140002217","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-02-26DOI: 10.1177/87552930241234306
Robert Reitherman
Resilience, achieving rapid recovery so that society can bounce back from a disaster, is a desirable goal, but sometimes the focus should be only on safety. The 2023 Turkey/Syria earthquake illustrates the case where limited resources should be prioritized on safety, that is, the collapse prevention performance objective, rather than the significantly more expensive goal of post-earthquake functionality.
{"title":"Dead people aren’t resilient","authors":"Robert Reitherman","doi":"10.1177/87552930241234306","DOIUrl":"https://doi.org/10.1177/87552930241234306","url":null,"abstract":"Resilience, achieving rapid recovery so that society can bounce back from a disaster, is a desirable goal, but sometimes the focus should be only on safety. The 2023 Turkey/Syria earthquake illustrates the case where limited resources should be prioritized on safety, that is, the collapse prevention performance objective, rather than the significantly more expensive goal of post-earthquake functionality.","PeriodicalId":11392,"journal":{"name":"Earthquake Spectra","volume":"21 1","pages":""},"PeriodicalIF":5.0,"publicationDate":"2024-02-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139981612","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Conventional earthquake risk modeling involves several notable simplifications, which neglect: (1) the effects on seismicity of interactions between adjacent faults and the long-term elastic rebound behavior of faults; (2) short-term hazard increases associated with aftershocks; and (3) the accumulation of damage in assets due to the occurrence of multiple earthquakes in a short time window, without repairs. Several recent earthquake events (e.g. 2010–2011 Canterbury earthquakes, New Zealand; 2019 Ridgecrest earthquakes, USA; and 2023 Turkey–Syria earthquakes) have emphasized the need for risk models to account for the aforementioned short- and long-term time-dependent characteristics of earthquake risk. This study specifically investigates the sensitivity of monetary loss (i.e. a possible earthquake-risk-model output) to these time dependencies, for a case-study portfolio in Central Italy. The investigation is intended to provide important insights for the catastrophe risk insurance and reinsurance industry. In addition to salient catastrophe risk insurance features, the end-to-end approach for time-dependent earthquake risk modeling used in this study incorporates recent updates in long-term time-dependent fault modeling, aftershock forecasting, and vulnerability modeling that accounts for damage accumulation. The sensitivity analysis approach presented may provide valuable guidance on the importance and appropriate treatment of time dependencies in regional (i.e. portfolio) earthquake risk models. We find that the long-term fault and aftershock occurrence models are the most crucial features of a time-dependent seismic risk model to constrain, at least for the monetary loss metrics examined in this study. Accounting for damage accumulation is also found to be important, if there is a high insurance deductible associated with portfolio assets.
{"title":"Investigating the sensitivity of losses to time-dependent components of seismic risk modeling","authors":"Salvatore Iacoletti, Gemma Cremen, Carmine Galasso","doi":"10.1177/87552930231226230","DOIUrl":"https://doi.org/10.1177/87552930231226230","url":null,"abstract":"Conventional earthquake risk modeling involves several notable simplifications, which neglect: (1) the effects on seismicity of interactions between adjacent faults and the long-term elastic rebound behavior of faults; (2) short-term hazard increases associated with aftershocks; and (3) the accumulation of damage in assets due to the occurrence of multiple earthquakes in a short time window, without repairs. Several recent earthquake events (e.g. 2010–2011 Canterbury earthquakes, New Zealand; 2019 Ridgecrest earthquakes, USA; and 2023 Turkey–Syria earthquakes) have emphasized the need for risk models to account for the aforementioned short- and long-term time-dependent characteristics of earthquake risk. This study specifically investigates the sensitivity of monetary loss (i.e. a possible earthquake-risk-model output) to these time dependencies, for a case-study portfolio in Central Italy. The investigation is intended to provide important insights for the catastrophe risk insurance and reinsurance industry. In addition to salient catastrophe risk insurance features, the end-to-end approach for time-dependent earthquake risk modeling used in this study incorporates recent updates in long-term time-dependent fault modeling, aftershock forecasting, and vulnerability modeling that accounts for damage accumulation. The sensitivity analysis approach presented may provide valuable guidance on the importance and appropriate treatment of time dependencies in regional (i.e. portfolio) earthquake risk models. We find that the long-term fault and aftershock occurrence models are the most crucial features of a time-dependent seismic risk model to constrain, at least for the monetary loss metrics examined in this study. Accounting for damage accumulation is also found to be important, if there is a high insurance deductible associated with portfolio assets.","PeriodicalId":11392,"journal":{"name":"Earthquake Spectra","volume":"49 1","pages":""},"PeriodicalIF":5.0,"publicationDate":"2024-02-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139949878","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-02-17DOI: 10.1177/87552930231222960
Cassie Gann-Phillips, Ashly Cabas, Chunyang Ji, Chris Cramer, James Kaklamanos, Oliver Boyd
The Atlantic and Gulf Coastal Plains (CPs) are characterized by widespread accumulations of low-velocity sediments and sedimentary rock that overlay high-velocity bedrock. Geology and sediment thickness greatly influence seismic wave propagation, but current regional ground motion amplification and seismic hazard models include limited characterization of these site conditions. In this study, a new regional seismic velocity model for the CPs is created by integrating shear wave velocity (VS) measurements, surface geology, and a sediment thickness model recently developed for the CPs. A reference rock VS of 3000 m/s has been assumed at the bottom of the sedimentary columns, which corresponds to the base of Cretaceous and Mesozoic sediments underlying the Atlantic CP and the Gulf CP, respectively. Measured VS profiles located throughout the CPs are sorted into five geologic groups of varying age, and median VS profiles are developed for each group by combining measured VS values within layer thicknesses defined by an assumed layering ratio. Statistical analyses are also conducted to test the appropriateness of the selected groups. A power law model with geology-informed coefficients is used to extend the median velocity models beyond the depths where measured data were available. The median VS profiles provide reasonable agreement with other generic models applicable for the region, but they also incorporate new information that enables more advanced characterizations of site response at regional scales and their effective incorporation into seismic hazard models and building codes. The proposed median velocity profiles can be assigned within a grid-based model of the CPs according to the spatial distribution of geologic units at the surface.
大西洋和海湾沿海平原（CPs）的特点是低速沉积物和沉积岩广泛堆积，覆盖在高速基岩之上。地质和沉积厚度在很大程度上影响着地震波的传播，但目前的区域地动放大和地震灾害模型对这些场地条件的描述十分有限。在本研究中，通过整合剪切波速度（VS）测量、地表地质以及最近为 CPs 开发的沉积厚度模型，为 CPs 建立了一个新的区域地震速度模型。假定沉积柱底部的参考岩石 VS 为 3000 米/秒，这分别相当于大西洋断裂带和海湾断裂带下白垩纪和中生代沉积物的底部。位于整个大陆坡的测量到的 VS 剖面被分为五个不同年龄的地质组，每组的 VS 剖面中值是通过合并按假定分层率确定的层厚内的测量 VS 值而得出的。此外，还进行了统计分析，以检验所选组别的适当性。使用带有地质信息系数的幂律模型，将中值速度模型扩展到可获得测量数据的深度之外。中值 VS 剖面与适用于该地区的其他通用模型具有合理的一致性，但它们也包含了新的信息，能够更先进地描述区域范围内的场地响应特征，并有效地将其纳入地震灾害模型和建筑规范中。建议的中值速度剖面可根据地表地质单元的空间分布分配到基于网格的 CPs 模型中。
{"title":"Regional seismic velocity model for the U.S. Atlantic and Gulf Coastal Plains based on measured shear wave velocity, sediment thickness, and surface geology","authors":"Cassie Gann-Phillips, Ashly Cabas, Chunyang Ji, Chris Cramer, James Kaklamanos, Oliver Boyd","doi":"10.1177/87552930231222960","DOIUrl":"https://doi.org/10.1177/87552930231222960","url":null,"abstract":"The Atlantic and Gulf Coastal Plains (CPs) are characterized by widespread accumulations of low-velocity sediments and sedimentary rock that overlay high-velocity bedrock. Geology and sediment thickness greatly influence seismic wave propagation, but current regional ground motion amplification and seismic hazard models include limited characterization of these site conditions. In this study, a new regional seismic velocity model for the CPs is created by integrating shear wave velocity (V<jats:sub>S</jats:sub>) measurements, surface geology, and a sediment thickness model recently developed for the CPs. A reference rock V<jats:sub>S</jats:sub> of 3000 m/s has been assumed at the bottom of the sedimentary columns, which corresponds to the base of Cretaceous and Mesozoic sediments underlying the Atlantic CP and the Gulf CP, respectively. Measured V<jats:sub>S</jats:sub> profiles located throughout the CPs are sorted into five geologic groups of varying age, and median V<jats:sub>S</jats:sub> profiles are developed for each group by combining measured V<jats:sub>S</jats:sub> values within layer thicknesses defined by an assumed layering ratio. Statistical analyses are also conducted to test the appropriateness of the selected groups. A power law model with geology-informed coefficients is used to extend the median velocity models beyond the depths where measured data were available. The median V<jats:sub>S</jats:sub> profiles provide reasonable agreement with other generic models applicable for the region, but they also incorporate new information that enables more advanced characterizations of site response at regional scales and their effective incorporation into seismic hazard models and building codes. The proposed median velocity profiles can be assigned within a grid-based model of the CPs according to the spatial distribution of geologic units at the surface.","PeriodicalId":11392,"journal":{"name":"Earthquake Spectra","volume":"19 1","pages":""},"PeriodicalIF":5.0,"publicationDate":"2024-02-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139949968","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-12-29DOI: 10.1177/87552930231215428
Mark D. Petersen, A. Shumway, P. Powers, E. Field, M. Moschetti, K. Jaiswal, K. Milner, S. Rezaeian, Arthur D. Frankel, A. Llenos, Andrew J. Michael, J. Altekruse, Sean K. Ahdi, Kyle B Withers, C. Mueller, Yuehua Zeng, Robert E Chase, Leah M Salditch, N. Luco, K. Rukstales, Julie A. Herrick, Demi L Girot, B. Aagaard, A. Bender, M. Blanpied, Richard W. Briggs, O. Boyd, B. Clayton, C. DuRoss, Eileen L. Evans, P. Haeussler, A. Hatem, K. L. Haynie, Elizabeth H. Hearn, Kaj Johnson, Zachary A Kortum, N. S. Kwong, A. Makdisi, H. B. Mason, Daniel E. McNamara, Devin F McPhillips, Paul G Okubo, M. Page, Fred F. Pollitz, J. Rubinstein, Bruce E. Shaw, Zheng-Kang Shen, Brian R Shiro, James A Smith, William J Stephenson, Eric M. Thompson, Jessica A. Thompson Jobe, Erin Wirth, R. Witter
The US National Seismic Hazard Model (NSHM) was updated in 2023 for all 50 states using new science on seismicity, fault ruptures, ground motions, and probabilistic techniques to produce a standard of practice for public policy and other engineering applications (defined for return periods greater than ∼475 or less than ∼10,000 years). Changes in 2023 time-independent seismic hazard (both increases and decreases compared to previous NSHMs) are substantial because the new model considers more data and updated earthquake rupture forecasts and ground-motion components. In developing the 2023 model, we tried to apply best available or applicable science based on advice of co-authors, more than 50 reviewers, and hundreds of hazard scientists and end-users, who attended public workshops and provided technical inputs. The hazard assessment incorporates new catalogs, declustering algorithms, gridded seismicity models, magnitude-scaling equations, fault-based structural and deformation models, multi-fault earthquake rupture forecast models, semi-empirical and simulation-based ground-motion models, and site amplification models conditioned on shear-wave velocities of the upper 30 m of soil and deeper sedimentary basin structures. Seismic hazard calculations yield hazard curves at hundreds of thousands of sites, ground-motion maps, uniform-hazard response spectra, and disaggregations developed for pseudo-spectral accelerations at 21 oscillator periods and two peak parameters, Modified Mercalli Intensity, and 8 site classes required by building codes and other public policy applications. Tests show the new model is consistent with past ShakeMap intensity observations. Sensitivity and uncertainty assessments ensure resulting ground motions are compatible with known hazard information and highlight the range and causes of variability in ground motions. We produce several impact products including building seismic design criteria, intensity maps, planning scenarios, and engineering risk assessments showing the potential physical and social impacts. These applications provide a basis for assessing, planning, and mitigating the effects of future earthquakes.
{"title":"The 2023 US 50-State National Seismic Hazard Model: Overview and implications","authors":"Mark D. Petersen, A. Shumway, P. Powers, E. Field, M. Moschetti, K. Jaiswal, K. Milner, S. Rezaeian, Arthur D. Frankel, A. Llenos, Andrew J. Michael, J. Altekruse, Sean K. Ahdi, Kyle B Withers, C. Mueller, Yuehua Zeng, Robert E Chase, Leah M Salditch, N. Luco, K. Rukstales, Julie A. Herrick, Demi L Girot, B. Aagaard, A. Bender, M. Blanpied, Richard W. Briggs, O. Boyd, B. Clayton, C. DuRoss, Eileen L. Evans, P. Haeussler, A. Hatem, K. L. Haynie, Elizabeth H. Hearn, Kaj Johnson, Zachary A Kortum, N. S. Kwong, A. Makdisi, H. B. Mason, Daniel E. McNamara, Devin F McPhillips, Paul G Okubo, M. Page, Fred F. Pollitz, J. Rubinstein, Bruce E. Shaw, Zheng-Kang Shen, Brian R Shiro, James A Smith, William J Stephenson, Eric M. Thompson, Jessica A. Thompson Jobe, Erin Wirth, R. Witter","doi":"10.1177/87552930231215428","DOIUrl":"https://doi.org/10.1177/87552930231215428","url":null,"abstract":"The US National Seismic Hazard Model (NSHM) was updated in 2023 for all 50 states using new science on seismicity, fault ruptures, ground motions, and probabilistic techniques to produce a standard of practice for public policy and other engineering applications (defined for return periods greater than ∼475 or less than ∼10,000 years). Changes in 2023 time-independent seismic hazard (both increases and decreases compared to previous NSHMs) are substantial because the new model considers more data and updated earthquake rupture forecasts and ground-motion components. In developing the 2023 model, we tried to apply best available or applicable science based on advice of co-authors, more than 50 reviewers, and hundreds of hazard scientists and end-users, who attended public workshops and provided technical inputs. The hazard assessment incorporates new catalogs, declustering algorithms, gridded seismicity models, magnitude-scaling equations, fault-based structural and deformation models, multi-fault earthquake rupture forecast models, semi-empirical and simulation-based ground-motion models, and site amplification models conditioned on shear-wave velocities of the upper 30 m of soil and deeper sedimentary basin structures. Seismic hazard calculations yield hazard curves at hundreds of thousands of sites, ground-motion maps, uniform-hazard response spectra, and disaggregations developed for pseudo-spectral accelerations at 21 oscillator periods and two peak parameters, Modified Mercalli Intensity, and 8 site classes required by building codes and other public policy applications. Tests show the new model is consistent with past ShakeMap intensity observations. Sensitivity and uncertainty assessments ensure resulting ground motions are compatible with known hazard information and highlight the range and causes of variability in ground motions. We produce several impact products including building seismic design criteria, intensity maps, planning scenarios, and engineering risk assessments showing the potential physical and social impacts. These applications provide a basis for assessing, planning, and mitigating the effects of future earthquakes.","PeriodicalId":11392,"journal":{"name":"Earthquake Spectra","volume":" 10","pages":""},"PeriodicalIF":5.0,"publicationDate":"2023-12-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139144953","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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