Pub Date : 2024-05-04DOI: 10.1177/87552930241246235
David McCallen, Arben Pitarka, Houjun Tang, Ramesh Pankajakshan, N Anders Petersson, Mamun Miah, Junfei Huang
Continuous advancements in scientific and engineering understanding of earthquake phenomena, combined with the associated development of representative physics-based models, is providing a foundation for high-performance, fault-to-structure earthquake simulations. However, regional-scale applications of high-performance models have been challenged by the computational requirements at the resolutions required for engineering risk assessments. The EarthQuake SIMulation (EQSIM) framework, a software application development under the US Department of Energy (DOE) Exascale Computing Project, is focused on overcoming the existing computational barriers and enabling routine regional-scale simulations at resolutions relevant to a breadth of engineered systems. This multidisciplinary software development—drawing upon expertise in geophysics, engineering, applied math and computer science—is preparing the advanced computational workflow necessary to fully exploit the DOE’s exaflop computer platforms coming online in the 2023 to 2024 timeframe. Achievement of the computational performance required for high-resolution regional models containing upward of hundreds of billions to trillions of model grid points requires numerical efficiency in every phase of a regional simulation. This includes run time start-up and regional model generation, effective distribution of the computational workload across thousands of computer nodes, efficient coupling of regional geophysics and local engineering models, and application-tailored highly efficient transfer, storage, and interrogation of very large volumes of simulation data. This article summarizes the most recent advancements and refinements incorporated in the workflow design for the EQSIM integrated fault-to-structure framework, which are based on extensive numerical testing across multiple graphics processing unit (GPU)-accelerated platforms, and demonstrates the computational performance achieved on the world’s first exaflop computer platform through representative regional-scale earthquake simulations for the San Francisco Bay Area in California, USA.
{"title":"Regional-scale fault-to-structure earthquake simulations with the EQSIM framework: Workflow maturation and computational performance on GPU-accelerated exascale platforms","authors":"David McCallen, Arben Pitarka, Houjun Tang, Ramesh Pankajakshan, N Anders Petersson, Mamun Miah, Junfei Huang","doi":"10.1177/87552930241246235","DOIUrl":"https://doi.org/10.1177/87552930241246235","url":null,"abstract":"Continuous advancements in scientific and engineering understanding of earthquake phenomena, combined with the associated development of representative physics-based models, is providing a foundation for high-performance, fault-to-structure earthquake simulations. However, regional-scale applications of high-performance models have been challenged by the computational requirements at the resolutions required for engineering risk assessments. The EarthQuake SIMulation (EQSIM) framework, a software application development under the US Department of Energy (DOE) Exascale Computing Project, is focused on overcoming the existing computational barriers and enabling routine regional-scale simulations at resolutions relevant to a breadth of engineered systems. This multidisciplinary software development—drawing upon expertise in geophysics, engineering, applied math and computer science—is preparing the advanced computational workflow necessary to fully exploit the DOE’s exaflop computer platforms coming online in the 2023 to 2024 timeframe. Achievement of the computational performance required for high-resolution regional models containing upward of hundreds of billions to trillions of model grid points requires numerical efficiency in every phase of a regional simulation. This includes run time start-up and regional model generation, effective distribution of the computational workload across thousands of computer nodes, efficient coupling of regional geophysics and local engineering models, and application-tailored highly efficient transfer, storage, and interrogation of very large volumes of simulation data. This article summarizes the most recent advancements and refinements incorporated in the workflow design for the EQSIM integrated fault-to-structure framework, which are based on extensive numerical testing across multiple graphics processing unit (GPU)-accelerated platforms, and demonstrates the computational performance achieved on the world’s first exaflop computer platform through representative regional-scale earthquake simulations for the San Francisco Bay Area in California, USA.","PeriodicalId":11392,"journal":{"name":"Earthquake Spectra","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140827428","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 : 2024-05-02DOI: 10.1177/87552930241243069
Sanaz Rezaeian, Peter M Powers, Jason Altekruse, Sean K Ahdi, Mark D Petersen, Allison M Shumway, Arthur D Frankel, Erin A Wirth, James A Smith, Morgan P Moschetti, Kyle B Withers, Julie A Herrick
The US Geological Survey National Seismic Hazard Models (NSHMs) are used to calculate earthquake ground-shaking intensities for design and rehabilitation of structures in the United States. The most recent 2014 and 2018 versions of the NSHM for the conterminous United States included major updates to ground-motion models (GMMs) for active and stable crustal tectonic settings; however, the subduction zone GMMs were largely unchanged. With the recent development of the next generation attenuation-subduction (NGA-Sub) GMMs, and recent progress in the utilization of “M9” Cascadia earthquake simulations, we now have access to improved models of ground shaking in the US subduction zones and the Seattle basin. The new NGA-Sub GMMs support multi-period response spectra calculations. They provide global models and regional terms specific to Cascadia and terms that account for deep-basin effects. This article focuses on the updates to subduction GMMs for implementation in the 2023 NSHM and compares them to the GMMs of previous NSHMs. Individual subduction GMMs, their weighted averages, and their impact on the estimated mean hazard relative to the 2018 NSHM are discussed. The updated logic trees include three of the new NGA-Sub GMMs and retain two older models to represent epistemic uncertainty in both the median and standard deviation of ground-shaking intensities at all periods of interest. Epistemic uncertainty is further represented by a three-point logic tree for the NGA-Sub median models. Finally, in the Seattle region, basin amplification factors are adjusted at long periods based on the state-of-the-art M9 Cascadia earthquake simulations. The new models increase the estimated mean hazard values at short periods and short source-to-site distances for interface earthquakes, but decrease them otherwise, relative to the 2018 NSHM. On softer soils, the new models cause decreases to the estimated mean hazard for long periods in the Puget Lowlands basin but increases within the deep Seattle portion of this basin for short periods relative to the 2018 NSHM.
{"title":"The 2023 US National Seismic Hazard Model: Subduction ground-motion models","authors":"Sanaz Rezaeian, Peter M Powers, Jason Altekruse, Sean K Ahdi, Mark D Petersen, Allison M Shumway, Arthur D Frankel, Erin A Wirth, James A Smith, Morgan P Moschetti, Kyle B Withers, Julie A Herrick","doi":"10.1177/87552930241243069","DOIUrl":"https://doi.org/10.1177/87552930241243069","url":null,"abstract":"The US Geological Survey National Seismic Hazard Models (NSHMs) are used to calculate earthquake ground-shaking intensities for design and rehabilitation of structures in the United States. The most recent 2014 and 2018 versions of the NSHM for the conterminous United States included major updates to ground-motion models (GMMs) for active and stable crustal tectonic settings; however, the subduction zone GMMs were largely unchanged. With the recent development of the next generation attenuation-subduction (NGA-Sub) GMMs, and recent progress in the utilization of “M9” Cascadia earthquake simulations, we now have access to improved models of ground shaking in the US subduction zones and the Seattle basin. The new NGA-Sub GMMs support multi-period response spectra calculations. They provide global models and regional terms specific to Cascadia and terms that account for deep-basin effects. This article focuses on the updates to subduction GMMs for implementation in the 2023 NSHM and compares them to the GMMs of previous NSHMs. Individual subduction GMMs, their weighted averages, and their impact on the estimated mean hazard relative to the 2018 NSHM are discussed. The updated logic trees include three of the new NGA-Sub GMMs and retain two older models to represent epistemic uncertainty in both the median and standard deviation of ground-shaking intensities at all periods of interest. Epistemic uncertainty is further represented by a three-point logic tree for the NGA-Sub median models. Finally, in the Seattle region, basin amplification factors are adjusted at long periods based on the state-of-the-art M9 Cascadia earthquake simulations. The new models increase the estimated mean hazard values at short periods and short source-to-site distances for interface earthquakes, but decrease them otherwise, relative to the 2018 NSHM. On softer soils, the new models cause decreases to the estimated mean hazard for long periods in the Puget Lowlands basin but increases within the deep Seattle portion of this basin for short periods relative to the 2018 NSHM.","PeriodicalId":11392,"journal":{"name":"Earthquake Spectra","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140827401","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 : 2024-04-27DOI: 10.1177/87552930241245940
Gerard J O’Reilly, Davit Shahnazaryan
Vulnerability functions relate loss to seismic intensity and can be developed via several approaches. They are a fundamental part of seismic risk assessment on a regional level and support decision-making and intervention strategies aimed at reducing risk. This article discusses a prominent analytical approach to developing seismic vulnerability models for buildings based on equivalent single-degree-of-freedom (SDOF) modeling, fragility function, and damage-to-loss model integration. The fundamental assumptions are scrutinized, and their principal drawbacks are highlighted. An alternative approach also based on an equivalent SDOF modeling approach is discussed but instead capitalizes on story loss functions (SLFs) as a means to more accurately compute economic losses and their sources. The main benefit is that the contribution of floor acceleration-based losses can be directly considered, and the disaggregation of losses is fully represented. A case study comparison is presented to highlight the similarities and key benefits. It is seen that the SLF-based approach can provide a much more comprehensive means to compute and communicate loss contributions among different element groups (i.e., structural, non-structural, and contents) and individual stories along the building height. Existing models can simply be adjusted to this approach and provide a more holistic view of risk. The benefits and potential applications in the (re)insurance sector are also discussed.
{"title":"On the utility of story loss functions for regional seismic vulnerability modeling and risk assessment","authors":"Gerard J O’Reilly, Davit Shahnazaryan","doi":"10.1177/87552930241245940","DOIUrl":"https://doi.org/10.1177/87552930241245940","url":null,"abstract":"Vulnerability functions relate loss to seismic intensity and can be developed via several approaches. They are a fundamental part of seismic risk assessment on a regional level and support decision-making and intervention strategies aimed at reducing risk. This article discusses a prominent analytical approach to developing seismic vulnerability models for buildings based on equivalent single-degree-of-freedom (SDOF) modeling, fragility function, and damage-to-loss model integration. The fundamental assumptions are scrutinized, and their principal drawbacks are highlighted. An alternative approach also based on an equivalent SDOF modeling approach is discussed but instead capitalizes on story loss functions (SLFs) as a means to more accurately compute economic losses and their sources. The main benefit is that the contribution of floor acceleration-based losses can be directly considered, and the disaggregation of losses is fully represented. A case study comparison is presented to highlight the similarities and key benefits. It is seen that the SLF-based approach can provide a much more comprehensive means to compute and communicate loss contributions among different element groups (i.e., structural, non-structural, and contents) and individual stories along the building height. Existing models can simply be adjusted to this approach and provide a more holistic view of risk. The benefits and potential applications in the (re)insurance sector are also discussed.","PeriodicalId":11392,"journal":{"name":"Earthquake Spectra","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-04-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140810702","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 : 2024-04-27DOI: 10.1177/87552930241246151
Mohammad Rabiepour, James Geoffrey Chase, Cong Zhou
This article introduces a simple, efficient spectral-based approach for rapid preliminary seismic assessment of earthquake-affected structures. Performance is validated using data from three highly earthquake-affected structures in New Zealand, where visual inspection with subjective outcomes missed damage, resulting in inaccurate and delayed decisions with significant social and economic losses. The three structures considered include (1) the instrumented Bank of New Zealand (BNZ) building; (2) the un-instrumented Queensgate Mall (QM) Complex; and (3) the un-instrumented Canterbury Television (CTV) building. This study uses these cases to highlight the importance of structural health monitoring (SHM) instrumentation and reliable quantified post-earthquake assessment methods in earthquake-prone areas, where each damaging earthquake and subsequent further-damaging aftershocks demand continuous monitoring to continuously assess damage and life safety risk. The simple, low-cost spectral analyses in this study clearly show the existence of damage and deterioration not fully discovered with standard visual inspection methods. This outcome highlights the importance of sensor networks and SHM instrumentation so quantitative, post-event analysis can rapidly augment and target further, more subjective visual inspection results.
{"title":"A spectral assessment for instant preliminary evaluation of structures after seismic events","authors":"Mohammad Rabiepour, James Geoffrey Chase, Cong Zhou","doi":"10.1177/87552930241246151","DOIUrl":"https://doi.org/10.1177/87552930241246151","url":null,"abstract":"This article introduces a simple, efficient spectral-based approach for rapid preliminary seismic assessment of earthquake-affected structures. Performance is validated using data from three highly earthquake-affected structures in New Zealand, where visual inspection with subjective outcomes missed damage, resulting in inaccurate and delayed decisions with significant social and economic losses. The three structures considered include (1) the instrumented Bank of New Zealand (BNZ) building; (2) the un-instrumented Queensgate Mall (QM) Complex; and (3) the un-instrumented Canterbury Television (CTV) building. This study uses these cases to highlight the importance of structural health monitoring (SHM) instrumentation and reliable quantified post-earthquake assessment methods in earthquake-prone areas, where each damaging earthquake and subsequent further-damaging aftershocks demand continuous monitoring to continuously assess damage and life safety risk. The simple, low-cost spectral analyses in this study clearly show the existence of damage and deterioration not fully discovered with standard visual inspection methods. This outcome highlights the importance of sensor networks and SHM instrumentation so quantitative, post-event analysis can rapidly augment and target further, more subjective visual inspection results.","PeriodicalId":11392,"journal":{"name":"Earthquake Spectra","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-04-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140810701","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 : 2024-04-12DOI: 10.1177/87552930241237250
Sean K Ahdi, Brad T Aagaard, Morgan P Moschetti, Grace A Parker, Oliver S Boyd, William J Stephenson
We assess how well the Next-Generation Attenuation-West 2 (NGA-West2) ground-motion models (GMMs), which are used in the US Geological Survey’s (USGS) National Seismic Hazard Model (NSHM) for crustal faults in the western United States, predict the observed basin response in the Great Valley of California, the Reno basin in Nevada, and Portland and Tualatin basins in Oregon. These GMMs rely on site parameters such as the time-averaged shear-wave velocity ( VS) in the upper 30 m of Earth’s crust ( VS30) and depths to 1.0 and 2.5 km/s shear-wave isosurfaces ( Z1.0 and Z2.5) to capture basin effects and were developed using observations and simulations primarily from the Los Angeles region in southern California. Using ground-motion records from mostly small-to-moderate earthquakes and mixed-effects regression analysis, we find that the GMMs perform well with our local basin-depth models for the California Great Valley. With our local basin-depth models for Reno, the GMMs do not perform as well for this relatively shallow basin and exhibit little sensitivity to the basin parameters used in the NGA-West2 GMMs. We also find good performance for the local Z1.0 model across the Portland region, whereas the local Z2.5 model provides little predictive power except at sites in the deepest part of the Tualatin basin. Additional work could improve the performance of the site and basin terms in the NGA-West2 GMMs for regions with geologic structure different than the deep basins in southern California and the Great Valley. In addition, we find significant discrepancies among the GMMs in how the uncertainty in the ground motion varies with basin depth and pseudospectral period. Our results can help guide seismic hazard analyses on whether to include these local basin-depth models.
{"title":"Empirical ground-motion basin response in the California Great Valley, Reno, Nevada, and Portland, Oregon","authors":"Sean K Ahdi, Brad T Aagaard, Morgan P Moschetti, Grace A Parker, Oliver S Boyd, William J Stephenson","doi":"10.1177/87552930241237250","DOIUrl":"https://doi.org/10.1177/87552930241237250","url":null,"abstract":"We assess how well the Next-Generation Attenuation-West 2 (NGA-West2) ground-motion models (GMMs), which are used in the US Geological Survey’s (USGS) National Seismic Hazard Model (NSHM) for crustal faults in the western United States, predict the observed basin response in the Great Valley of California, the Reno basin in Nevada, and Portland and Tualatin basins in Oregon. These GMMs rely on site parameters such as the time-averaged shear-wave velocity ( V<jats:sub>S</jats:sub>) in the upper 30 m of Earth’s crust ( V<jats:sub>S30</jats:sub>) and depths to 1.0 and 2.5 km/s shear-wave isosurfaces ( Z<jats:sub>1.0</jats:sub> and Z<jats:sub>2.5</jats:sub>) to capture basin effects and were developed using observations and simulations primarily from the Los Angeles region in southern California. Using ground-motion records from mostly small-to-moderate earthquakes and mixed-effects regression analysis, we find that the GMMs perform well with our local basin-depth models for the California Great Valley. With our local basin-depth models for Reno, the GMMs do not perform as well for this relatively shallow basin and exhibit little sensitivity to the basin parameters used in the NGA-West2 GMMs. We also find good performance for the local Z<jats:sub>1.0</jats:sub> model across the Portland region, whereas the local Z<jats:sub>2.5</jats:sub> model provides little predictive power except at sites in the deepest part of the Tualatin basin. Additional work could improve the performance of the site and basin terms in the NGA-West2 GMMs for regions with geologic structure different than the deep basins in southern California and the Great Valley. In addition, we find significant discrepancies among the GMMs in how the uncertainty in the ground motion varies with basin depth and pseudospectral period. Our results can help guide seismic hazard analyses on whether to include these local basin-depth models.","PeriodicalId":11392,"journal":{"name":"Earthquake Spectra","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140590147","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 : 2024-04-08DOI: 10.1177/87552930241237716
Jessica Thangjitham, Mervyn Kowalsky
The steel in reinforced concrete (RC) members that form plastic hinges must possess sufficient strain capacity to dissipate seismic deformation demands. Unfortunately, there is limited information on the seismic strain demands of bridge column plastic hinges. Instead, designers rely on a perception of cyclic strain capacity that is an approximate rule of thumb. A standard methodology needs to be established for quantifying the strain demand on these structural members as a function of the expected seismic hazard. To develop this methodology, 1944 columns were analyzed with nonlinear time-history analyses (NLTHAs) using ground motions from a range of earthquakes. This study evaluates the strain demand on RC bridge columns by defining the relationship between the strain demand and earthquake intensity. The results of the model are defined in terms of the peak tensile strain of the reinforcing bar, [Formula: see text]. The earthquake intensity with the highest correlation to the [Formula: see text] was determined to be the elastic spectral displacement at the optimal period ([Formula: see text]), which is defined as 75% of the effective period. The relationship between [Formula: see text] and [Formula: see text] can be used to predict the strain demand for an RC bridge column at a given geographic location. Results are presented as a probability density function (PDF), representing strain demand, compared to a PDF of the column capacity. The intersection of the capacity curve and demand curve represents the maximum acceptable strain given as a function of [Formula: see text]. This methodology can help understand the demand placed on a structural system given a region’s seismicity.
{"title":"The strain demand of reinforced concrete bridge columns under seismic loading","authors":"Jessica Thangjitham, Mervyn Kowalsky","doi":"10.1177/87552930241237716","DOIUrl":"https://doi.org/10.1177/87552930241237716","url":null,"abstract":"The steel in reinforced concrete (RC) members that form plastic hinges must possess sufficient strain capacity to dissipate seismic deformation demands. Unfortunately, there is limited information on the seismic strain demands of bridge column plastic hinges. Instead, designers rely on a perception of cyclic strain capacity that is an approximate rule of thumb. A standard methodology needs to be established for quantifying the strain demand on these structural members as a function of the expected seismic hazard. To develop this methodology, 1944 columns were analyzed with nonlinear time-history analyses (NLTHAs) using ground motions from a range of earthquakes. This study evaluates the strain demand on RC bridge columns by defining the relationship between the strain demand and earthquake intensity. The results of the model are defined in terms of the peak tensile strain of the reinforcing bar, [Formula: see text]. The earthquake intensity with the highest correlation to the [Formula: see text] was determined to be the elastic spectral displacement at the optimal period ([Formula: see text]), which is defined as 75% of the effective period. The relationship between [Formula: see text] and [Formula: see text] can be used to predict the strain demand for an RC bridge column at a given geographic location. Results are presented as a probability density function (PDF), representing strain demand, compared to a PDF of the column capacity. The intersection of the capacity curve and demand curve represents the maximum acceptable strain given as a function of [Formula: see text]. This methodology can help understand the demand placed on a structural system given a region’s seismicity.","PeriodicalId":11392,"journal":{"name":"Earthquake Spectra","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140590353","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 : 2024-04-06DOI: 10.1177/87552930241234271
Masahiro Shirato, Yuichi Odawara
A series of large-scale earthquakes occurred on February 6 in southern Turkey. The authors had the opportunity to join the Japan Disaster Relief (JDR) Expert Team and visit several damaged areas in Turkey from March 10 to 12, 2023. This article highlights damage cases of a road tunnel and several road bridges the authors observed around Antakya, Nurdağı, and Malatya. From the features of the observations, this article discusses the following three items for further study in the seismic design of road bridges: (1) seismic details for robustness, (2) seismic responses of bridges with longer natural periods, and (3) post-event inspection.
{"title":"Field observations on the damage to road bridges after the 2023 Turkey Earthquake","authors":"Masahiro Shirato, Yuichi Odawara","doi":"10.1177/87552930241234271","DOIUrl":"https://doi.org/10.1177/87552930241234271","url":null,"abstract":"A series of large-scale earthquakes occurred on February 6 in southern Turkey. The authors had the opportunity to join the Japan Disaster Relief (JDR) Expert Team and visit several damaged areas in Turkey from March 10 to 12, 2023. This article highlights damage cases of a road tunnel and several road bridges the authors observed around Antakya, Nurdağı, and Malatya. From the features of the observations, this article discusses the following three items for further study in the seismic design of road bridges: (1) seismic details for robustness, (2) seismic responses of bridges with longer natural periods, and (3) post-event inspection.","PeriodicalId":11392,"journal":{"name":"Earthquake Spectra","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-04-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140590356","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 : 2024-04-04DOI: 10.1177/87552930241237546
Jingyang Tan, Jinjun Hu
The S-net, a large-scale network of permanent ocean-bottom seismographs in the Japan Trench, consisting of 150 stations, has recorded a large number of offshore ground motions that can be used to establish the empirical attenuation relationship of offshore ground motions in the subduction zone. Due to the different attenuation characteristics among different earthquake types in subduction zones, the earthquakes are classified into four tectonic types of subduction slab, interface, shallow crustal, and upper-mantle earthquakes according to the classification scheme of Zhao et al. (2015). Predictive models and uncertainties in offshore ground motions were investigated for different earthquake types. This study establishes a horizontal offshore subduction slab earthquake ground-motion model (GMM) and compares the offshore and onshore slab earthquake GMMs. As the site conditions at ocean-bottom stations are different from those at land stations, the effects of water depth and sediment thickness are taken into account in the offshore slab earthquake GMM. Due to differences in the burial methods of ocean-bottom stations, stations were divided into buried and unburied to investigate the effects of the burial methods. Therefore, regression analysis was used to propose an offshore slab earthquake GMM considering the magnitude, focal depth, distance, water depth, sediment thickness, and burial method. By separating the within-event residuals, the single-station standard deviation is presented. Compared to the onshore GMM, the predicted spectra of the offshore GMM are significantly larger at long periods. For the attenuation rate, the offshore attenuation rate is lower than that of the onshore attenuation rate for short periods, but is basically consistent with the onshore attenuation rate for long periods. The proposed GMM can be used to predict the offshore ground motions for slab earthquakes with rupture distances less than 300 km, focal depths less than 110 km, and moment magnitude between 4 and 7.4.
{"title":"Horizontal ground-motion model for subduction slab earthquakes using offshore ground motions in the Japan Trench area","authors":"Jingyang Tan, Jinjun Hu","doi":"10.1177/87552930241237546","DOIUrl":"https://doi.org/10.1177/87552930241237546","url":null,"abstract":"The S-net, a large-scale network of permanent ocean-bottom seismographs in the Japan Trench, consisting of 150 stations, has recorded a large number of offshore ground motions that can be used to establish the empirical attenuation relationship of offshore ground motions in the subduction zone. Due to the different attenuation characteristics among different earthquake types in subduction zones, the earthquakes are classified into four tectonic types of subduction slab, interface, shallow crustal, and upper-mantle earthquakes according to the classification scheme of Zhao et al. (2015). Predictive models and uncertainties in offshore ground motions were investigated for different earthquake types. This study establishes a horizontal offshore subduction slab earthquake ground-motion model (GMM) and compares the offshore and onshore slab earthquake GMMs. As the site conditions at ocean-bottom stations are different from those at land stations, the effects of water depth and sediment thickness are taken into account in the offshore slab earthquake GMM. Due to differences in the burial methods of ocean-bottom stations, stations were divided into buried and unburied to investigate the effects of the burial methods. Therefore, regression analysis was used to propose an offshore slab earthquake GMM considering the magnitude, focal depth, distance, water depth, sediment thickness, and burial method. By separating the within-event residuals, the single-station standard deviation is presented. Compared to the onshore GMM, the predicted spectra of the offshore GMM are significantly larger at long periods. For the attenuation rate, the offshore attenuation rate is lower than that of the onshore attenuation rate for short periods, but is basically consistent with the onshore attenuation rate for long periods. The proposed GMM can be used to predict the offshore ground motions for slab earthquakes with rupture distances less than 300 km, focal depths less than 110 km, and moment magnitude between 4 and 7.4.","PeriodicalId":11392,"journal":{"name":"Earthquake Spectra","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140590311","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 : 2024-04-03DOI: 10.1177/87552930241232372
Morgan P Moschetti, Eric M Thompson, Kyle Withers
We develop basin-depth-scaling models (i.e. “basin terms”) from the long-period ([Formula: see text]) simulated ground motions of the Southern California Earthquake Center (SCEC) CyberShake project for use in seismic hazard analyses at sites within the sedimentary basins of southern California. Basin terms use the Next Generation Attenuation (NGA)-West-2 ground-motion models (GMMs) as reference models and use their functional forms with slight modifications. We investigate the use of two approaches to incorporate the time-averaged shear-wave velocity in the upper 30 m ([Formula: see text]) in these calculations and find that the use of site-specific and uniform [Formula: see text] has minor effects on the resulting basin terms for this data set. By centering the simulated ground motions on the basin terms, we separate the information from the simulations about absolute ground-motion level from information relating to the relative amplifications, such as the differences between shallow- and deep-basin sites. Recent observations from sedimentary basins of southern California indicate that additional amplification effect may persist at relatively shallow basin depths (i.e. the GMM basin terms should have positive values when differential depths, [Formula: see text], are near zero), and we present models for “centered” and “adjusted” basin-depth scaling models that reflect this potential. The simulation-modified GMMs are appropriate for crustal sources and for deep-basin sites ([Formula: see text]) within basins of the Greater Los Angeles region, for the magnitudes and distances defined by each of the reference NGA-West-2 GMMs.
{"title":"Basin effects from 3D simulated ground motions in the Greater Los Angeles region for use in seismic hazard analyses","authors":"Morgan P Moschetti, Eric M Thompson, Kyle Withers","doi":"10.1177/87552930241232372","DOIUrl":"https://doi.org/10.1177/87552930241232372","url":null,"abstract":"We develop basin-depth-scaling models (i.e. “basin terms”) from the long-period ([Formula: see text]) simulated ground motions of the Southern California Earthquake Center (SCEC) CyberShake project for use in seismic hazard analyses at sites within the sedimentary basins of southern California. Basin terms use the Next Generation Attenuation (NGA)-West-2 ground-motion models (GMMs) as reference models and use their functional forms with slight modifications. We investigate the use of two approaches to incorporate the time-averaged shear-wave velocity in the upper 30 m ([Formula: see text]) in these calculations and find that the use of site-specific and uniform [Formula: see text] has minor effects on the resulting basin terms for this data set. By centering the simulated ground motions on the basin terms, we separate the information from the simulations about absolute ground-motion level from information relating to the relative amplifications, such as the differences between shallow- and deep-basin sites. Recent observations from sedimentary basins of southern California indicate that additional amplification effect may persist at relatively shallow basin depths (i.e. the GMM basin terms should have positive values when differential depths, [Formula: see text], are near zero), and we present models for “centered” and “adjusted” basin-depth scaling models that reflect this potential. The simulation-modified GMMs are appropriate for crustal sources and for deep-basin sites ([Formula: see text]) within basins of the Greater Los Angeles region, for the magnitudes and distances defined by each of the reference NGA-West-2 GMMs.","PeriodicalId":11392,"journal":{"name":"Earthquake Spectra","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140590235","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 : 2024-04-03DOI: 10.1177/87552930241236765
Joanna M Holmgren, Maximilian J Werner, Katsuichiro Goda, Manuela Villani, Vitor Silva, Patrick Chindandali
The southern East African Rift System (EARS) is an early-stage continental rift with a deep seismogenic zone. It is associated with a low-to-moderate seismic hazard, but due to its short and sparse instrumental record, there is a lack of ground-motion studies in the region. Instead, seismic hazard assessments have commonly relied on a combination of active crustal and stable continental ground-motion models (GMMs) from other regions without accounting for the unusual geological setting of this region and evaluating their suitability. Here, we use a newly compiled southern EARS ground-motion database to compare six active crustal GMMs and four stable continental GMMs. We find that the active crustal GMMs tend to underestimate the ground-motion intensities observed, while the stable continental GMMs overestimate them. This is particularly pronounced in the high-frequency intensity measures (>5 Hz). We also use the referenced empirical approach and develop a new region-specific GMM for southern EARS. Both the ranked GMMs and our new GMM result in large residual variabilities, highlighting the need for local geotechnical information to better constrain site conditions.
{"title":"Ranking and developing ground-motion models for Southeastern Africa","authors":"Joanna M Holmgren, Maximilian J Werner, Katsuichiro Goda, Manuela Villani, Vitor Silva, Patrick Chindandali","doi":"10.1177/87552930241236765","DOIUrl":"https://doi.org/10.1177/87552930241236765","url":null,"abstract":"The southern East African Rift System (EARS) is an early-stage continental rift with a deep seismogenic zone. It is associated with a low-to-moderate seismic hazard, but due to its short and sparse instrumental record, there is a lack of ground-motion studies in the region. Instead, seismic hazard assessments have commonly relied on a combination of active crustal and stable continental ground-motion models (GMMs) from other regions without accounting for the unusual geological setting of this region and evaluating their suitability. Here, we use a newly compiled southern EARS ground-motion database to compare six active crustal GMMs and four stable continental GMMs. We find that the active crustal GMMs tend to underestimate the ground-motion intensities observed, while the stable continental GMMs overestimate them. This is particularly pronounced in the high-frequency intensity measures (>5 Hz). We also use the referenced empirical approach and develop a new region-specific GMM for southern EARS. Both the ranked GMMs and our new GMM result in large residual variabilities, highlighting the need for local geotechnical information to better constrain site conditions.","PeriodicalId":11392,"journal":{"name":"Earthquake Spectra","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140590146","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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