Pub Date : 2024-08-08DOI: 10.1177/87552930241266741
Peter M Powers, Jason M Altekruse, Andrea L Llenos, Andy J Michael, Kirstie L Haynie, Peter J Haeussler, Adrian M Bender, Sanaz Rezaeian, Morgan P Moschetti, James A Smith, Richard W Briggs, Robert C Witter, Charles S Mueller, Yuehua Zeng, Demi L Girot, Julie A Herrick, Allison M Shumway, Mark D Petersen
US Geological Survey (USGS) National Seismic Hazard Models (NSHMs) are used extensively for seismic design regulations in the United States and earthquake scenario development, as well as risk assessment and mitigation for both buildings and infrastructure. This 2023 update of the long-term, time-independent Alaska NSHM includes substantial changes to both the earthquake rupture forecast (ERF) and ground motion models (GMMs). The ERF includes numerous additions to the finite-fault model, considers two deformation models, and introduces updated declustering and smoothing algorithms in the gridded background seismicity model. For the Alaska–Aleutian subduction zone, megathrust earthquakes occur on an updated structural and segmentation model, and the moment magnitude (M) 8+ rupture and rate model include a logic tree branch that considers slip rates derived from geodetic models of interface coupling. The megathrust model considers multiple models of down-dip width, and magnitudes are computed using newly developed scaling relations. For subduction intraslab events and subduction interface events with M < 7, the 2023 update uses a smoothed seismicity model with rupture depths derived from Slab2. The 2023 model updates GMMs in all tectonic settings using the recently published Next Generation Attenuation Subduction (NGA-Sub) GMMs for subduction interface and intraslab events, and the NGA-West2 GMMs for active crustal settings. Collectively, additions and updates to the Alaska NSHM result in hazard increases across most of south-central Alaska relative to the previous model, published in 2007. These changes are primarily due to the adoption of updated rate models for the large-magnitude interface events and the NGA-Sub GMMs that have much higher aleatory variability (sigma), consistent with global observations, and that include models of epistemic uncertainty.
{"title":"The 2023 Alaska National Seismic Hazard Model","authors":"Peter M Powers, Jason M Altekruse, Andrea L Llenos, Andy J Michael, Kirstie L Haynie, Peter J Haeussler, Adrian M Bender, Sanaz Rezaeian, Morgan P Moschetti, James A Smith, Richard W Briggs, Robert C Witter, Charles S Mueller, Yuehua Zeng, Demi L Girot, Julie A Herrick, Allison M Shumway, Mark D Petersen","doi":"10.1177/87552930241266741","DOIUrl":"https://doi.org/10.1177/87552930241266741","url":null,"abstract":"US Geological Survey (USGS) National Seismic Hazard Models (NSHMs) are used extensively for seismic design regulations in the United States and earthquake scenario development, as well as risk assessment and mitigation for both buildings and infrastructure. This 2023 update of the long-term, time-independent Alaska NSHM includes substantial changes to both the earthquake rupture forecast (ERF) and ground motion models (GMMs). The ERF includes numerous additions to the finite-fault model, considers two deformation models, and introduces updated declustering and smoothing algorithms in the gridded background seismicity model. For the Alaska–Aleutian subduction zone, megathrust earthquakes occur on an updated structural and segmentation model, and the moment magnitude (M) 8+ rupture and rate model include a logic tree branch that considers slip rates derived from geodetic models of interface coupling. The megathrust model considers multiple models of down-dip width, and magnitudes are computed using newly developed scaling relations. For subduction intraslab events and subduction interface events with M < 7, the 2023 update uses a smoothed seismicity model with rupture depths derived from Slab2. The 2023 model updates GMMs in all tectonic settings using the recently published Next Generation Attenuation Subduction (NGA-Sub) GMMs for subduction interface and intraslab events, and the NGA-West2 GMMs for active crustal settings. Collectively, additions and updates to the Alaska NSHM result in hazard increases across most of south-central Alaska relative to the previous model, published in 2007. These changes are primarily due to the adoption of updated rate models for the large-magnitude interface events and the NGA-Sub GMMs that have much higher aleatory variability (sigma), consistent with global observations, and that include models of epistemic uncertainty.","PeriodicalId":11392,"journal":{"name":"Earthquake Spectra","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141946226","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 : 2024-08-07DOI: 10.1177/87552930241262775
Arsam Taslimi, Floriana Petrone
This study investigates the vulnerability of long-span suspension bridges to spatially variable vertical ground motions (SV-VGMs). While of recognized importance, a comprehensive understanding of this topic has been traditionally limited by the unavailability of an adequate number of arrays of motions. In this work, 10 simulations of a large-magnitude Hayward Fault earthquake are utilized to perform site-specific structural response assessments of a suspension bridge under different load scenarios. A detailed nonlinear model representative of the West San Francisco-Oakland Bay Bridge is employed as the case study structure. Four sets of nonlinear time-history analyses are performed with and without VGMs and with and without the incorporation of spatial variability to offer the basis for a complete comparison of the demand distributions across different load cases. Results indicate that VGMs largely influence the response of the bridge decks in the vertical direction, with an increase in drifts up to 2× for the case of synchronous input and up to 2.5× for the case of asynchronous inputs. The analysis of the bridge response in the time and frequency domain across all load cases reveals a high sensitivity of the decks’ response to minor time lags in input motions of comparable amplitude, which are seen to activate the contribution of higher modes to the structural response. Evidence from this study points to the potential of severely underestimating structural demands if the (even limited) spatial variability of the input motions is not incorporated correctly. For the case study structure, the probability of exceeding the onset of nonlinearity in the short decks at the design earthquake level is seen to increase by a factor of about two when considering SV-VGMs as opposed to synchronous horizontal motions only.
{"title":"Vulnerability of suspension bridges to spatially variable vertical ground motions","authors":"Arsam Taslimi, Floriana Petrone","doi":"10.1177/87552930241262775","DOIUrl":"https://doi.org/10.1177/87552930241262775","url":null,"abstract":"This study investigates the vulnerability of long-span suspension bridges to spatially variable vertical ground motions (SV-VGMs). While of recognized importance, a comprehensive understanding of this topic has been traditionally limited by the unavailability of an adequate number of arrays of motions. In this work, 10 simulations of a large-magnitude Hayward Fault earthquake are utilized to perform site-specific structural response assessments of a suspension bridge under different load scenarios. A detailed nonlinear model representative of the West San Francisco-Oakland Bay Bridge is employed as the case study structure. Four sets of nonlinear time-history analyses are performed with and without VGMs and with and without the incorporation of spatial variability to offer the basis for a complete comparison of the demand distributions across different load cases. Results indicate that VGMs largely influence the response of the bridge decks in the vertical direction, with an increase in drifts up to 2× for the case of synchronous input and up to 2.5× for the case of asynchronous inputs. The analysis of the bridge response in the time and frequency domain across all load cases reveals a high sensitivity of the decks’ response to minor time lags in input motions of comparable amplitude, which are seen to activate the contribution of higher modes to the structural response. Evidence from this study points to the potential of severely underestimating structural demands if the (even limited) spatial variability of the input motions is not incorporated correctly. For the case study structure, the probability of exceeding the onset of nonlinearity in the short decks at the design earthquake level is seen to increase by a factor of about two when considering SV-VGMs as opposed to synchronous horizontal motions only.","PeriodicalId":11392,"journal":{"name":"Earthquake Spectra","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141946228","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 : 2024-08-07DOI: 10.1177/87552930241263618
Kendra Johnson, Thomas Chartier, Marco Pagani, Yesica Perez, Vladimir Guzmán, Maria Betania Roque de Medina, Richard Styron, Catalina Yepes-Estrada
The Dominican Republic experiences moderate to high seismic hazard mostly caused by oblique convergence at the Caribbean/North American plate boundary that manifests as subduction zones, less-pronounced subduction-like trenches with thrust faulting, long strike-slip faults parallel to the plate boundary, and onshore deformation. Historical earthquakes have damaged the Dominican Republic’s large cities and those in neighboring Haiti, once requiring relocation. Given this, the Dominican Republic joined the “Training and Communication for Earthquake Risk Assessment” (TREQ) project funded by the United States Agency for International Development, which aimed to increase earthquake risk assessment capacity in Latin American cities. The TREQ project was the basis for developing an openly available probabilistic seismic hazard model for the Dominican Republic. The input model was developed from two main datasets: a homogenized earthquake catalog and an active faults database that combines results of recent local projects with a global database. The seismic source characterization used these to constrain source geometries and occurrence rates for active shallow crustal earthquakes, subduction interfaces and subduction-like thrusts, and intraslab earthquakes. Shallow crustal earthquakes, including those on subduction-like thrusts, are modeled by smoothed seismicity and fault sources, the latter using pre-defined geometries that permit multi-fault ruptures. Seismicity on the Puerto Rico Trench subduction interface is modeled as a fault source, while intraslab sources use pre-defined gridded ruptures inside the intraslab volume. The source characterization applies epistemic uncertainties to modeling assumptions affecting occurrence rates and maximum magnitudes. The ground motion characterization used residual analyses from past regional projects as a basis, updating some components with more recent ground motion models. Computed hazard results reinforce those from recent studies in terms of geographical hazard patterns and levels. For 475-year return periods, peak ground acceleration (PGA) in Santiago de los Caballeros reaches 0.50 g, controlled by the Septentrional Fault, while all tectonic region types contribute to the PGA 0.31 g computed for Santo Domingo.
{"title":"Probabilistic seismic hazard analysis for the Dominican Republic","authors":"Kendra Johnson, Thomas Chartier, Marco Pagani, Yesica Perez, Vladimir Guzmán, Maria Betania Roque de Medina, Richard Styron, Catalina Yepes-Estrada","doi":"10.1177/87552930241263618","DOIUrl":"https://doi.org/10.1177/87552930241263618","url":null,"abstract":"The Dominican Republic experiences moderate to high seismic hazard mostly caused by oblique convergence at the Caribbean/North American plate boundary that manifests as subduction zones, less-pronounced subduction-like trenches with thrust faulting, long strike-slip faults parallel to the plate boundary, and onshore deformation. Historical earthquakes have damaged the Dominican Republic’s large cities and those in neighboring Haiti, once requiring relocation. Given this, the Dominican Republic joined the “Training and Communication for Earthquake Risk Assessment” (TREQ) project funded by the United States Agency for International Development, which aimed to increase earthquake risk assessment capacity in Latin American cities. The TREQ project was the basis for developing an openly available probabilistic seismic hazard model for the Dominican Republic. The input model was developed from two main datasets: a homogenized earthquake catalog and an active faults database that combines results of recent local projects with a global database. The seismic source characterization used these to constrain source geometries and occurrence rates for active shallow crustal earthquakes, subduction interfaces and subduction-like thrusts, and intraslab earthquakes. Shallow crustal earthquakes, including those on subduction-like thrusts, are modeled by smoothed seismicity and fault sources, the latter using pre-defined geometries that permit multi-fault ruptures. Seismicity on the Puerto Rico Trench subduction interface is modeled as a fault source, while intraslab sources use pre-defined gridded ruptures inside the intraslab volume. The source characterization applies epistemic uncertainties to modeling assumptions affecting occurrence rates and maximum magnitudes. The ground motion characterization used residual analyses from past regional projects as a basis, updating some components with more recent ground motion models. Computed hazard results reinforce those from recent studies in terms of geographical hazard patterns and levels. For 475-year return periods, peak ground acceleration (PGA) in Santiago de los Caballeros reaches 0.50 g, controlled by the Septentrional Fault, while all tectonic region types contribute to the PGA 0.31 g computed for Santo Domingo.","PeriodicalId":11392,"journal":{"name":"Earthquake Spectra","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141946237","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 : 2024-07-31DOI: 10.1177/87552930241262753
Egemen Sönmez, Mario E Rodriguez
The February 2023 earthquakes in Türkiye caused widespread devastation and fatalities, highlighting the critical contrast in the seismic performance of reinforced concrete (RC) buildings with moment-resistant frames and those with structural walls. This study employs analyses of nonlinear single-degree-of-freedom (SDOF) systems using selected accelerograms from the earthquakes to evaluate the behavior of these structural systems. Three SDOF systems representing flexible and stiffer frame buildings, alongside RC wall buildings, were examined. The results highlighted the susceptibility of frame buildings to severe damage and collapse compared with the excellent performance of RC wall buildings. Moreover, the study emphasizes a shift of design focus from life safety to functional recovery. It also identifies potential scenarios regarding consecutive earthquake effects. Overall, the findings advocate adequately designed RC wall buildings for enhanced seismic performance and immediate occupation following major earthquakes.
{"title":"Frame buildings are not an answer for earthquakes: The case of the February 2023 earthquakes in Türkiye","authors":"Egemen Sönmez, Mario E Rodriguez","doi":"10.1177/87552930241262753","DOIUrl":"https://doi.org/10.1177/87552930241262753","url":null,"abstract":"The February 2023 earthquakes in Türkiye caused widespread devastation and fatalities, highlighting the critical contrast in the seismic performance of reinforced concrete (RC) buildings with moment-resistant frames and those with structural walls. This study employs analyses of nonlinear single-degree-of-freedom (SDOF) systems using selected accelerograms from the earthquakes to evaluate the behavior of these structural systems. Three SDOF systems representing flexible and stiffer frame buildings, alongside RC wall buildings, were examined. The results highlighted the susceptibility of frame buildings to severe damage and collapse compared with the excellent performance of RC wall buildings. Moreover, the study emphasizes a shift of design focus from life safety to functional recovery. It also identifies potential scenarios regarding consecutive earthquake effects. Overall, the findings advocate adequately designed RC wall buildings for enhanced seismic performance and immediate occupation following major earthquakes.","PeriodicalId":11392,"journal":{"name":"Earthquake Spectra","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141863125","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 : 2024-07-31DOI: 10.1177/87552930241266742
Jeannette Sutton, Savanah Crouch, Nicholas Waugh, Michele M Wood
Ridgecrest, CA, experienced the Searles Valley earthquake sequence in 2019 and a “false” earthquake alert in 2020, providing a unique opportunity to examine the effects of earthquake experience on future responses to informational cues to action (i.e., earthquake alert), as well as reactions to a “false” alert. We conducted in-depth interviews with 41 residents using the protective action decision-making model as a theoretical framework. Interviewees reported a variety of environmental cues that signaled the onset of an earthquake, including sensing a foreshock, hearing the earth rumble, hearing objects fall to the floor and break, and observing unusual animal behavior. Fewer individuals received social cues to action. More individuals reported performing “drop, cover, and hold on,” and fewer reported standing in a doorway in response to the 2020 alert than had done so in the prior 2019 earthquake. Several respondents reported maintaining protective actions well after the “false” alert was issued, and many waited more than 5 min before determining there was no threat present. Prior experience of the 2019 earthquake series affected perceptions of the earthquake alert and what actions to take; however, there was limited knowledge of how the ShakeAlert system worked to monitor, detect, and model earthquakes via earthquake early warning to persons at risk. Findings indicate there is a need for additional public education about ShakeAlert-powered earthquake early warning, including how far in advance one can expect to receive an alert, as well as the protective actions one should take and when to take them.
{"title":"“We ran outside and waited for it to come”: Resident experiences in response to a false earthquake early warning","authors":"Jeannette Sutton, Savanah Crouch, Nicholas Waugh, Michele M Wood","doi":"10.1177/87552930241266742","DOIUrl":"https://doi.org/10.1177/87552930241266742","url":null,"abstract":"Ridgecrest, CA, experienced the Searles Valley earthquake sequence in 2019 and a “false” earthquake alert in 2020, providing a unique opportunity to examine the effects of earthquake experience on future responses to informational cues to action (i.e., earthquake alert), as well as reactions to a “false” alert. We conducted in-depth interviews with 41 residents using the protective action decision-making model as a theoretical framework. Interviewees reported a variety of environmental cues that signaled the onset of an earthquake, including sensing a foreshock, hearing the earth rumble, hearing objects fall to the floor and break, and observing unusual animal behavior. Fewer individuals received social cues to action. More individuals reported performing “drop, cover, and hold on,” and fewer reported standing in a doorway in response to the 2020 alert than had done so in the prior 2019 earthquake. Several respondents reported maintaining protective actions well after the “false” alert was issued, and many waited more than 5 min before determining there was no threat present. Prior experience of the 2019 earthquake series affected perceptions of the earthquake alert and what actions to take; however, there was limited knowledge of how the ShakeAlert system worked to monitor, detect, and model earthquakes via earthquake early warning to persons at risk. Findings indicate there is a need for additional public education about ShakeAlert-powered earthquake early warning, including how far in advance one can expect to receive an alert, as well as the protective actions one should take and when to take them.","PeriodicalId":11392,"journal":{"name":"Earthquake Spectra","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141863229","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 : 2024-07-30DOI: 10.1177/87552930241262766
Alexandra Sarmiento, Danielle Madugo, Andi Shen, Timothy Dawson, Chris Madugo, Stephen Thompson, Yousef Bozorgnia, Stéphane Baize, Paolo Boncio, Albert Kottke, Grigorios Lavrentiadis, Silvia Mazzoni, Christopher Milliner, Fiia Nurminen, Francesco Visini
New predictive models for fault displacement and surface rupture hazard analysis developed through the Fault Displacement Hazard Initiative (FDHI) research program require a high-quality empirical database to apply advanced statistical methods and improve hazard estimates. This article discusses the development and contents of the FDHI Project database. We systematically collected, reviewed, and organized fault displacement measurements, surface rupture maps, and supporting information from the scientific literature. A framework was developed and implemented to classify principal and distributed faulting. Best-estimate net displacement amplitudes were calculated from slip component measurements and quality codes were assigned to all net displacement values. The database contains 75 historical, surface-rupturing crustal earthquakes ranging from M 4.9 to 8.0. Thirty-five earthquakes have a strike-slip faulting mechanism, while 25 and 15 events are reverse/reverse-oblique and normal/normal-oblique, respectively. Although most of the earthquakes are from Western North America, Japan, and other active tectonic regions, there are nine reverse faulting events from the stable continental region of Australia. The database contains over 40,000 individual fault displacement measurements for various slip components from roughly 28,000 observation sites. Geographic coordinates are included for all data, and event-specific coordinate systems are provided for each earthquake that transform data into an along-strike dimension. Our new database provides a standardized collection of surface rupture and fault displacement data and metadata that is the result of a comprehensive effort to create a reliable and stable product for the FDHI model development teams and the geoscience community.
{"title":"Database for the Fault Displacement Hazard Initiative Project","authors":"Alexandra Sarmiento, Danielle Madugo, Andi Shen, Timothy Dawson, Chris Madugo, Stephen Thompson, Yousef Bozorgnia, Stéphane Baize, Paolo Boncio, Albert Kottke, Grigorios Lavrentiadis, Silvia Mazzoni, Christopher Milliner, Fiia Nurminen, Francesco Visini","doi":"10.1177/87552930241262766","DOIUrl":"https://doi.org/10.1177/87552930241262766","url":null,"abstract":"New predictive models for fault displacement and surface rupture hazard analysis developed through the Fault Displacement Hazard Initiative (FDHI) research program require a high-quality empirical database to apply advanced statistical methods and improve hazard estimates. This article discusses the development and contents of the FDHI Project database. We systematically collected, reviewed, and organized fault displacement measurements, surface rupture maps, and supporting information from the scientific literature. A framework was developed and implemented to classify principal and distributed faulting. Best-estimate net displacement amplitudes were calculated from slip component measurements and quality codes were assigned to all net displacement values. The database contains 75 historical, surface-rupturing crustal earthquakes ranging from M 4.9 to 8.0. Thirty-five earthquakes have a strike-slip faulting mechanism, while 25 and 15 events are reverse/reverse-oblique and normal/normal-oblique, respectively. Although most of the earthquakes are from Western North America, Japan, and other active tectonic regions, there are nine reverse faulting events from the stable continental region of Australia. The database contains over 40,000 individual fault displacement measurements for various slip components from roughly 28,000 observation sites. Geographic coordinates are included for all data, and event-specific coordinate systems are provided for each earthquake that transform data into an along-strike dimension. Our new database provides a standardized collection of surface rupture and fault displacement data and metadata that is the result of a comprehensive effort to create a reliable and stable product for the FDHI model development teams and the geoscience community.","PeriodicalId":11392,"journal":{"name":"Earthquake Spectra","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141863232","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 : 2024-07-30DOI: 10.1177/87552930241262044
Chenhao Wu, Henry V Burton
The number of ground motions used in nonlinear response history analysis (NRHA) determines the precision of the parameter estimates obtained in seismic performance assessments. While this issue has been extensively studied in the earthquake engineering literature, the relationship of probability model misspecification to parameter estimation uncertainty, and the implication to the required number of ground motions needed for NRHA, has not been examined. Probability model misspecification has the potential to increase estimation uncertainty and hence requires a greater number of ground motions to achieve the same precision compared to when misspecification is disregarded. This study develops a procedure to determine the required number of ground motions in seismic code-prescriptive and risk-based assessments with possible probability model misspecification. Specifically, we employ the quasi-maximum likelihood estimation (QMLE), which is robust to probability model misspecification, to evaluate estimation uncertainty. The QMLE approach is applied to an archetype California bridge under the two seismic assessment scenarios. In the code-prescriptive assessment, misspecification errors are identified for dispersion estimates of the bridge column ductility demand. In the most extreme case of the risk-based evaluation, misspecification increases the estimation uncertainty of the mean annual frequency of exceeding a limit state by as much as three times, which substantially increases the required number of ground motions. Based on the findings from this study, we advocate for the use of QMLE to detect and rectify the implications of model misspecification to estimation uncertainty and the number of ground motions used in probabilistic seismic performance assessments.
{"title":"Effects of probability model misspecification on the number of ground motions required for seismic performance assessment","authors":"Chenhao Wu, Henry V Burton","doi":"10.1177/87552930241262044","DOIUrl":"https://doi.org/10.1177/87552930241262044","url":null,"abstract":"The number of ground motions used in nonlinear response history analysis (NRHA) determines the precision of the parameter estimates obtained in seismic performance assessments. While this issue has been extensively studied in the earthquake engineering literature, the relationship of probability model misspecification to parameter estimation uncertainty, and the implication to the required number of ground motions needed for NRHA, has not been examined. Probability model misspecification has the potential to increase estimation uncertainty and hence requires a greater number of ground motions to achieve the same precision compared to when misspecification is disregarded. This study develops a procedure to determine the required number of ground motions in seismic code-prescriptive and risk-based assessments with possible probability model misspecification. Specifically, we employ the quasi-maximum likelihood estimation (QMLE), which is robust to probability model misspecification, to evaluate estimation uncertainty. The QMLE approach is applied to an archetype California bridge under the two seismic assessment scenarios. In the code-prescriptive assessment, misspecification errors are identified for dispersion estimates of the bridge column ductility demand. In the most extreme case of the risk-based evaluation, misspecification increases the estimation uncertainty of the mean annual frequency of exceeding a limit state by as much as three times, which substantially increases the required number of ground motions. Based on the findings from this study, we advocate for the use of QMLE to detect and rectify the implications of model misspecification to estimation uncertainty and the number of ground motions used in probabilistic seismic performance assessments.","PeriodicalId":11392,"journal":{"name":"Earthquake Spectra","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141863230","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}
The Turkey–Syria earthquakes that occurred on February 6, 2023, have caused significant human casualties and economic damage. Emergency services require quick and accurate assessments of widespread building damage in affected areas. This can be facilitated by using remote sensing methods, specifically all-day and all-weather Synthetic Aperture Radar (SAR). In this study, we aimed to improve the detection of building anomalies in earthquake-affected areas using SAR images. To achieve this, we employed Recurrent Neural Network (RNN) to train coherence time series and predict co-seismic coherence. This approach allowed us to generate a Damage Proxy Map (DPM) for building damage assessment. The results of our study indicated that the estimated proportion of building damage in Kahramanmaras was approximately 24.08%. These findings were consistent with the actual damage observed in the field. Moreover, when utilizing the mean and standard deviation of coherence time series, our method achieved higher accuracy (0.761) and a lower false alarm rate (0.136) compared to directly using coherence with only two views of SAR data. Overall, our study demonstrates that this method provides an accurate and reliable approach for post-earthquake building damage assessment.
{"title":"Large-scale building damage assessment based on recurrent neural networks using SAR coherence time series: A case study of 2023 Turkey–Syria earthquake","authors":"Yanchen Yang, Chou Xie, Bangsen Tian, Yihong Guo, Yu Zhu, Ying Yang, Haoran Fang, Shuaichen Bian, Ming Zhang","doi":"10.1177/87552930241262761","DOIUrl":"https://doi.org/10.1177/87552930241262761","url":null,"abstract":"The Turkey–Syria earthquakes that occurred on February 6, 2023, have caused significant human casualties and economic damage. Emergency services require quick and accurate assessments of widespread building damage in affected areas. This can be facilitated by using remote sensing methods, specifically all-day and all-weather Synthetic Aperture Radar (SAR). In this study, we aimed to improve the detection of building anomalies in earthquake-affected areas using SAR images. To achieve this, we employed Recurrent Neural Network (RNN) to train coherence time series and predict co-seismic coherence. This approach allowed us to generate a Damage Proxy Map (DPM) for building damage assessment. The results of our study indicated that the estimated proportion of building damage in Kahramanmaras was approximately 24.08%. These findings were consistent with the actual damage observed in the field. Moreover, when utilizing the mean and standard deviation of coherence time series, our method achieved higher accuracy (0.761) and a lower false alarm rate (0.136) compared to directly using coherence with only two views of SAR data. Overall, our study demonstrates that this method provides an accurate and reliable approach for post-earthquake building damage assessment.","PeriodicalId":11392,"journal":{"name":"Earthquake Spectra","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141863235","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 : 2024-07-27DOI: 10.1177/87552930241262043
Selcuk Bas, Jeffrey Hunt, B. Gencturk, Ezra Jampole, Y. B. Sonmezer, Brent Chancellor, Patrick C. Bassal, Murat Celiker, N. Apaydın, Halil Sezen
This article presents a summary of the damage observed in bridges in the regions affected by the 6 February 2023 Kahramanmaras, Türkiye earthquake sequence. A bridge database was developed based on the observations from multiple reconnaissance groups that visited the bridges. These reconnaissance groups collectively visited 140 individual bridges that were subjected to various intensities of ground shaking. The severity of the observed damage ranged from no damage to total collapse. The types of damage to bridge components mainly included cracking and shifting of abutments, failure of pier cap shear blocks, shifting or dislodging of bearing pads, cracking of girders and loss of prestress, plastic hinging at pier bases, residual pier drift, and distress to deck surfaces, handrails, and carried utilities. Recorded and estimated seismic intensity measures are presented for each bridge site, and statistical information and correlations were developed considering the intensity of shaking, bridge parameters, and observed damage. Observations from a few visited sites are presented as case studies to illustrate the common failure mechanisms. The bridge database and presented results are expected to serve as a reference for further analysis, such as statistical verification, correlation, or damage estimations, and discussion regarding the mitigation of the observed vulnerabilities of bridges in Türkiye and those with similar construction worldwide.
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