E. Manea, Anna E. Kaiser, M. Hill, L. Wotherspoon, Sandra Bourguignon, Sanjay S. Bora, A. Stolte
Although earthquake site effects play a crucial role in the evaluation of local seismic hazard and associated risk, their quantification over the frequency range of interest for engineering applications still remains challenging. Mapping the local amplification at high resolution is difficult even in seismically active cities such as Wellington, New Zealand. Employing traditional methods to map amplification, such as the standard spectral ratio (SSR), is realistic only with sufficient density of strong-motion stations (SMS) across the city and the presence of a suitable rock reference station. Recently, hybrid standard spectral ratio methodologies (SSRh) have been proposed to fill in the gaps and provide estimates at much finer spatial resolution. SSRh combines traditional SSR, calculated on earthquake data between a soil reference and a rock station, with SSR computed from simultaneous ambient vibration recordings (SSRn) at a temporary location and the soil reference site within the sedimentary basin. In the last decade, over 450 single-station ambient noise measurements were undertaken across Wellington, and no collocated soil reference station is available, making the SSRh method as it stands impossible to apply. To overcome this limitation, we propose an adaptation of SSRh to capture the same basin response between a soil site and soil reference station as in the case of the synchronous ambient vibration data. We employ an additional interim step that uses the traditional SSRn between each of the soil sites and a rock reference broadband station recording synchronous long-term ambient vibration. The resulting empirical amplification model using the SSRh adaptation is in good agreement with the available SSR at SMS. Amplification factors up to 10 are present along the Centreport area, where significant damage was observed during the Mw 7.8 Kaikōura earthquake. By employing the adjusted SSRh methodology, we were able to develop a first-level high-resolution empirical site amplification model for Wellington. The approach provides an attractive solution for the evaluation of site effects across regions where a significant number of unsynchronized ambient vibration measurements are available.
尽管地震场地效应在评估当地地震灾害和相关风险方面发挥着至关重要的作用，但在工程应用所关注的频率范围内对其进行量化仍然具有挑战性。即使是在新西兰惠灵顿这样地震活跃的城市，也很难绘制出高分辨率的局部放大图。采用标准频谱比（SSR）等传统方法绘制扩增图，只有在全市强震动台站（SMS）密度足够大且有合适的岩石基准台站的情况下才可行。最近，有人提出了混合标准谱比方法（SSRh），以填补空白，提供更精细的空间分辨率估算。SSRh 将根据土壤基准站和岩石站之间的地震数据计算的传统 SSR 与根据沉积盆地内临时地点和土壤基准站的同步环境振动记录（SSRn）计算的 SSR 结合在一起。在过去的十年中，惠灵顿全境共进行了 450 多次单站环境噪声测量，但却没有可用于同一地点的土壤基准站，因此目前的 SSRh 方法无法应用。为了克服这一局限性，我们建议对 SSRh 进行调整，以捕捉土壤站点和土壤参考站之间的盆地响应，就像同步环境振动数据一样。我们采用了一个额外的临时步骤，在每个土壤站点和记录长期同步环境振动的岩石参考宽带站之间使用传统的 SSRn。使用 SSRh 适配得出的经验放大模型与 SMS 现有的 SSR 非常吻合。中心港地区沿线的放大系数高达 10，在 7.8 级 Kaikōura 地震中，该地区受到严重破坏。通过采用调整后的 SSRh 方法，我们能够为惠灵顿开发出第一级高分辨率经验站点放大模型。该方法为在有大量非同步环境振动测量数据的地区评估场地效应提供了一个极具吸引力的解决方案。
{"title":"A High-Resolution Site Amplification Map for Wellington, New Zealand","authors":"E. Manea, Anna E. Kaiser, M. Hill, L. Wotherspoon, Sandra Bourguignon, Sanjay S. Bora, A. Stolte","doi":"10.1785/0220230227","DOIUrl":"https://doi.org/10.1785/0220230227","url":null,"abstract":"Although earthquake site effects play a crucial role in the evaluation of local seismic hazard and associated risk, their quantification over the frequency range of interest for engineering applications still remains challenging. Mapping the local amplification at high resolution is difficult even in seismically active cities such as Wellington, New Zealand. Employing traditional methods to map amplification, such as the standard spectral ratio (SSR), is realistic only with sufficient density of strong-motion stations (SMS) across the city and the presence of a suitable rock reference station. Recently, hybrid standard spectral ratio methodologies (SSRh) have been proposed to fill in the gaps and provide estimates at much finer spatial resolution. SSRh combines traditional SSR, calculated on earthquake data between a soil reference and a rock station, with SSR computed from simultaneous ambient vibration recordings (SSRn) at a temporary location and the soil reference site within the sedimentary basin. In the last decade, over 450 single-station ambient noise measurements were undertaken across Wellington, and no collocated soil reference station is available, making the SSRh method as it stands impossible to apply. To overcome this limitation, we propose an adaptation of SSRh to capture the same basin response between a soil site and soil reference station as in the case of the synchronous ambient vibration data. We employ an additional interim step that uses the traditional SSRn between each of the soil sites and a rock reference broadband station recording synchronous long-term ambient vibration. The resulting empirical amplification model using the SSRh adaptation is in good agreement with the available SSR at SMS. Amplification factors up to 10 are present along the Centreport area, where significant damage was observed during the Mw 7.8 Kaikōura earthquake. By employing the adjusted SSRh methodology, we were able to develop a first-level high-resolution empirical site amplification model for Wellington. The approach provides an attractive solution for the evaluation of site effects across regions where a significant number of unsynchronized ambient vibration measurements are available.","PeriodicalId":21687,"journal":{"name":"Seismological Research Letters","volume":"6 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2023-11-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139232717","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. Wuestefeld, Z. Spica, K. Aderhold, Hsin-Hua Huang, Kuo-Fong Ma, V. Lai, Meghan Miller, L. Urmantseva, Daniel Zapf, Daniel C. Bowden, Pascal Edme, T. Kiers, Antonio P. Rinaldi, Katinka Tuinstra, Camille Jestin, Sergio Diaz-Meza, P. Jousset, C. Wollin, A. Ugalde, Sandra Ruiz Barajas, B. Gaite, G. Currenti, M. Prestifilippo, Eiichiro Araki, Takashi Tonegawa, S. D. de Ridder, A. Nowacki, Fabian Lindner, M. Schoenball, Christoph Wetter, Hong-Hu Zhu, Alan F. Baird, R. A. Rørstadbotnen, Jonathan B. Ajo‐Franklin, Yuanyuan Ma, R. Abbott, Kathleen M. Hodgkinson, R. Porritt, Christian Stanciu, Agatha Podrasky, David Hill, B. Biondi, Siyuan Yuan, Bin Luo, Sergei Nikitin, J. P. Morten, V. Dumitru, Werner Lienhart, Erin Cunningham, Herbert Wang
During February 2023, a total of 32 individual distributed acoustic sensing (DAS) systems acted jointly as a global seismic monitoring network. The aim of this Global DAS Month campaign was to coordinate a diverse network of organizations, instruments, and file formats to gain knowledge and move toward the next generation of earthquake monitoring networks. During this campaign, 156 earthquakes of magnitude 5 or larger were reported by the U.S. Geological Survey and contributors shared data for 60 min after each event’s origin time. Participating systems represent a variety of manufacturers, a range of recording parameters, and varying cable emplacement settings (e.g., shallow burial, borehole, subaqueous, and dark fiber). Monitored cable lengths vary between 152 and 120,129 m, with channel spacing between 1 and 49 m. The data has a total size of 6.8 TB, and are available for free download. Organizing and executing the Global DAS Month has produced a unique dataset for further exploration and highlighted areas of further development for the seismological community to address.
{"title":"The Global DAS Month of February 2023","authors":"A. Wuestefeld, Z. Spica, K. Aderhold, Hsin-Hua Huang, Kuo-Fong Ma, V. Lai, Meghan Miller, L. Urmantseva, Daniel Zapf, Daniel C. Bowden, Pascal Edme, T. Kiers, Antonio P. Rinaldi, Katinka Tuinstra, Camille Jestin, Sergio Diaz-Meza, P. Jousset, C. Wollin, A. Ugalde, Sandra Ruiz Barajas, B. Gaite, G. Currenti, M. Prestifilippo, Eiichiro Araki, Takashi Tonegawa, S. D. de Ridder, A. Nowacki, Fabian Lindner, M. Schoenball, Christoph Wetter, Hong-Hu Zhu, Alan F. Baird, R. A. Rørstadbotnen, Jonathan B. Ajo‐Franklin, Yuanyuan Ma, R. Abbott, Kathleen M. Hodgkinson, R. Porritt, Christian Stanciu, Agatha Podrasky, David Hill, B. Biondi, Siyuan Yuan, Bin Luo, Sergei Nikitin, J. P. Morten, V. Dumitru, Werner Lienhart, Erin Cunningham, Herbert Wang","doi":"10.1785/0220230180","DOIUrl":"https://doi.org/10.1785/0220230180","url":null,"abstract":"During February 2023, a total of 32 individual distributed acoustic sensing (DAS) systems acted jointly as a global seismic monitoring network. The aim of this Global DAS Month campaign was to coordinate a diverse network of organizations, instruments, and file formats to gain knowledge and move toward the next generation of earthquake monitoring networks. During this campaign, 156 earthquakes of magnitude 5 or larger were reported by the U.S. Geological Survey and contributors shared data for 60 min after each event’s origin time. Participating systems represent a variety of manufacturers, a range of recording parameters, and varying cable emplacement settings (e.g., shallow burial, borehole, subaqueous, and dark fiber). Monitored cable lengths vary between 152 and 120,129 m, with channel spacing between 1 and 49 m. The data has a total size of 6.8 TB, and are available for free download. Organizing and executing the Global DAS Month has produced a unique dataset for further exploration and highlighted areas of further development for the seismological community to address.","PeriodicalId":21687,"journal":{"name":"Seismological Research Letters","volume":"31 2","pages":""},"PeriodicalIF":3.3,"publicationDate":"2023-11-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139234660","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
K. K. Thingbaijam, Matthew C. Gerstenberger, Chris Rollins, R. V. Van Dissen, Sepideh J. Rastin, Christopher J. DiCaprio, D. Rhoades, A. Christophersen
Probabilistic seismic hazard analysis requires a seismicity rate model, or in other words, a forecast of earthquake rates. In the New Zealand National Seismic Hazard Model 2022, the seismicity rate model is constructed through independent forecasts of earthquakes on mapped faults and earthquakes distributed over cells in a spatial grid. Here, we explore the seismicity rate model for upper plate (hypocenter ≥ 40 km) events, to investigate the shape of magnitude–frequency distributions (MFDs) considering events nucleating (or for which the hypocenters are located) within individual fault zone. We find that more than 80% of the fault zones have MFDs that are better described by a Gutenberg–Richter (GR) distribution, instead of a characteristic distribution (i.e., rates of larger magnitudes much higher than the GR trend). Furthermore, the MFD classifications are neither influenced by time-dependent (and time-independent) considerations nor directly affected by the size (or area) of the fault zones. Fault zones with faster slip rates (>20 mm/yr) exhibit characteristic MFDs, whereas those with slower slip rates may or may not. Although multifault ruptures are prevalent in the characteristic distributions, large maximum magnitude (Mw >8.0) plays a pivotal role producing a characteristic MFD. On the other hand, physically unconnected multifault ruptures (i.e., involving rupture jumps ≥ 10 km) are mostly observed with GR distributions.
地震灾害概率分析需要一个地震率模型，或者换句话说，需要对地震率进行预测。在新西兰国家地震危险模型 2022 中，地震率模型是通过对绘制的断层上的地震和分布在空间网格单元上的地震进行独立预测而构建的。在此，我们探讨了上板块（下心≥ 40 千米）事件的地震率模型，以研究考虑到在单个断层带内成核（或下心位于其中）的事件的震级-频率分布（MFDs）形状。我们发现，80%以上的断层带的震级频率分布更适合用古登堡-里克特分布（GR）来描述，而不是特征分布（即较大震级发生率远高于古登堡-里克特分布趋势）。此外，MFD 分类既不受时间相关（和时间无关）因素的影响，也不直接受断层带大小（或面积）的影响。滑动速率较快（>20 毫米/年）的断层带表现出特征性的多断层破裂，而滑动速率较慢的断层带可能会也可能不会表现出特征性的多断层破裂。虽然多断层破裂在特征分布中很普遍，但大的最大震级（Mw >8.0）在产生特征性多断层破裂中起着关键作用。另一方面，在 GR 分布中观察到的大多是物理上不相连的多断层破裂（即涉及跃变≥ 10 km 的破裂）。
{"title":"Characteristic versus Gutenberg–Richter Nucleation-Based Magnitude–Frequency Distributions in the New Zealand National Seismic Hazard Model 2022","authors":"K. K. Thingbaijam, Matthew C. Gerstenberger, Chris Rollins, R. V. Van Dissen, Sepideh J. Rastin, Christopher J. DiCaprio, D. Rhoades, A. Christophersen","doi":"10.1785/0220230220","DOIUrl":"https://doi.org/10.1785/0220230220","url":null,"abstract":"Probabilistic seismic hazard analysis requires a seismicity rate model, or in other words, a forecast of earthquake rates. In the New Zealand National Seismic Hazard Model 2022, the seismicity rate model is constructed through independent forecasts of earthquakes on mapped faults and earthquakes distributed over cells in a spatial grid. Here, we explore the seismicity rate model for upper plate (hypocenter ≥ 40 km) events, to investigate the shape of magnitude–frequency distributions (MFDs) considering events nucleating (or for which the hypocenters are located) within individual fault zone. We find that more than 80% of the fault zones have MFDs that are better described by a Gutenberg–Richter (GR) distribution, instead of a characteristic distribution (i.e., rates of larger magnitudes much higher than the GR trend). Furthermore, the MFD classifications are neither influenced by time-dependent (and time-independent) considerations nor directly affected by the size (or area) of the fault zones. Fault zones with faster slip rates (>20 mm/yr) exhibit characteristic MFDs, whereas those with slower slip rates may or may not. Although multifault ruptures are prevalent in the characteristic distributions, large maximum magnitude (Mw >8.0) plays a pivotal role producing a characteristic MFD. On the other hand, physically unconnected multifault ruptures (i.e., involving rupture jumps ≥ 10 km) are mostly observed with GR distributions.","PeriodicalId":21687,"journal":{"name":"Seismological Research Letters","volume":"87 7","pages":""},"PeriodicalIF":3.3,"publicationDate":"2023-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139256101","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Andrew Howell, Andrew Nicol, Sanjay S. Bora, Matthew C. Gerstenberger, R. V. Van Dissen, Chris Chamberlain, Christopher J. DiCaprio, Chris Rollins, Mark Stirling, Oakley Jurgens, Bruce E. Shaw
Multifault ruptures are common for historical earthquakes, and here we consider their impact on seismic hazard. We compare ground-shaking hazard forecasts from the 2022 Aotearoa New Zealand National Seismic Hazard Model (NZ NSHM 2022), which incorporates many multifault ruptures (referred to as the multifault model) with modeled hazard from a simpler model of characteristic earthquakes on individual faults or fault segments (referred to as the segmented model). The multifault model includes very-low-probability rupture lengths of up to ∼1100 km and a mean of 221–234 km, whereas the segmented model primarily comprises rupture lengths of <200 km (mean, 43–51 km) and the maximum of 414 km. The annual rates of Mw 6.9–7.5 earthquakes are more than an order of magnitude higher for the segmented model (0.132–0.24/yr; recurrence times ∼4–7 yr) than the multifault model (0.027/yr; recurrence times 37 yr). Conversely, the rates of earthquakes are similar for segmented and multifault models at Mw>7.5 (0.018–0.031/yr; recurrence times 32–56 yr). Despite differences in rupture lengths and annual rates of earthquakes, the calculated ground-shaking hazard at 10% probability of exceedance (PoE) in 50 yr for the segmented model differs by <55% compared with the multifault model for 95% of sites across Aotearoa New Zealand. For 50% of sites, the modeled hazard differs by <20% between the two models. If a distributed seismicity model (DSM) is included in the hazard calculations, 95% of sites differ in modeled hazard by <18%, and 50% of sites differ by <2.2%. In most areas, seismic hazard at 10% PoE in 50 yr is greater for the segmented model than the multifault model, with notable exceptions along the central Alpine fault in the western South Island and the Taupō volcanic zone in the central North Island.
{"title":"Comparison of Ground-Shaking Hazard for Segmented versus Multifault Earthquake-Rupture Models in Aotearoa New Zealand","authors":"Andrew Howell, Andrew Nicol, Sanjay S. Bora, Matthew C. Gerstenberger, R. V. Van Dissen, Chris Chamberlain, Christopher J. DiCaprio, Chris Rollins, Mark Stirling, Oakley Jurgens, Bruce E. Shaw","doi":"10.1785/0220230240","DOIUrl":"https://doi.org/10.1785/0220230240","url":null,"abstract":"Multifault ruptures are common for historical earthquakes, and here we consider their impact on seismic hazard. We compare ground-shaking hazard forecasts from the 2022 Aotearoa New Zealand National Seismic Hazard Model (NZ NSHM 2022), which incorporates many multifault ruptures (referred to as the multifault model) with modeled hazard from a simpler model of characteristic earthquakes on individual faults or fault segments (referred to as the segmented model). The multifault model includes very-low-probability rupture lengths of up to ∼1100 km and a mean of 221–234 km, whereas the segmented model primarily comprises rupture lengths of <200 km (mean, 43–51 km) and the maximum of 414 km. The annual rates of Mw 6.9–7.5 earthquakes are more than an order of magnitude higher for the segmented model (0.132–0.24/yr; recurrence times ∼4–7 yr) than the multifault model (0.027/yr; recurrence times 37 yr). Conversely, the rates of earthquakes are similar for segmented and multifault models at Mw>7.5 (0.018–0.031/yr; recurrence times 32–56 yr). Despite differences in rupture lengths and annual rates of earthquakes, the calculated ground-shaking hazard at 10% probability of exceedance (PoE) in 50 yr for the segmented model differs by <55% compared with the multifault model for 95% of sites across Aotearoa New Zealand. For 50% of sites, the modeled hazard differs by <20% between the two models. If a distributed seismicity model (DSM) is included in the hazard calculations, 95% of sites differ in modeled hazard by <18%, and 50% of sites differ by <2.2%. In most areas, seismic hazard at 10% PoE in 50 yr is greater for the segmented model than the multifault model, with notable exceptions along the central Alpine fault in the western South Island and the Taupō volcanic zone in the central North Island.","PeriodicalId":21687,"journal":{"name":"Seismological Research Letters","volume":"22 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2023-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139256898","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"The Difficult Balance among Scientific, Technical, and Political Issues in Seismic Hazard Assessment","authors":"Dario Albarello, Roberto Paolucci","doi":"10.1785/0220230203","DOIUrl":"https://doi.org/10.1785/0220230203","url":null,"abstract":"","PeriodicalId":21687,"journal":{"name":"Seismological Research Letters","volume":"57 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2023-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139263209","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
K. Marano, M. Hearne, K. Jaiswal, Eric M. Thompson, C. Bruce Worden, David J. Wald
Archival earthquake studies often focus on event and source characteristics for use in earthquake catalogs, seismotectonic understanding, and ground-motion studies—many of these targeting better constraints for probabilistic seismic-hazard analyses. The ShakeMap Atlas, in contrast, focuses on spatial distribution of shaking for the historical events, providing the best constraints at all locations that experienced significant shaking for each event, facilitating analyses of human experience, damage, and induced hazards (ground failure). The aim of the Atlas is to gain a general understanding and depiction of the shaking distribution for a suite of canonical earthquakes, and, coupled with loss data for each event, to provide a basis for earthquake loss model calibration, among other uses. Although the initial motivation for developing the ShakeMap Atlas was calibrating the U.S. Geological Survey (USGS) Prompt Assessment of Global Earthquakes for Response system, over time, the Atlas has proved to be a useful tool for its users, and, as such, its scope has been vastly expanded in this newest version. The fourth version of the USGS ShakeMap Atlas is an openly available compilation of over 14,000 ShakeMaps of significant global earthquakes between 1900 and 2020. This revision includes: (1) the latest version of the ShakeMap software that provides refined uncertainty estimations and improved methods to combine macroseismic observations with updated ground-motion models; (2) an updated earthquake source catalog; (3) a refined strategy to select suites of prediction and conversion equations based on a new seismotectonic regionalization scheme; and (4) expanded macroseismic intensity and ground-motion datasets. We also tabulate reported economic losses and fatalities for Atlas events where such data are openly available. These changes make the new ShakeMap Atlas a self-consistent, calibrated catalog invaluable for investigating near-source ground motions, as well as seismic hazard, scenario, risk, and loss-model development and testing.
{"title":"ShakeMap Atlas 4.0 and AtlasCat: An Archive of the Recent and the Historical Earthquake ShakeMaps, and Impacts for Global Hazard Analyses and Loss Model Calibration","authors":"K. Marano, M. Hearne, K. Jaiswal, Eric M. Thompson, C. Bruce Worden, David J. Wald","doi":"10.1785/0220220324","DOIUrl":"https://doi.org/10.1785/0220220324","url":null,"abstract":"Archival earthquake studies often focus on event and source characteristics for use in earthquake catalogs, seismotectonic understanding, and ground-motion studies—many of these targeting better constraints for probabilistic seismic-hazard analyses. The ShakeMap Atlas, in contrast, focuses on spatial distribution of shaking for the historical events, providing the best constraints at all locations that experienced significant shaking for each event, facilitating analyses of human experience, damage, and induced hazards (ground failure). The aim of the Atlas is to gain a general understanding and depiction of the shaking distribution for a suite of canonical earthquakes, and, coupled with loss data for each event, to provide a basis for earthquake loss model calibration, among other uses. Although the initial motivation for developing the ShakeMap Atlas was calibrating the U.S. Geological Survey (USGS) Prompt Assessment of Global Earthquakes for Response system, over time, the Atlas has proved to be a useful tool for its users, and, as such, its scope has been vastly expanded in this newest version. The fourth version of the USGS ShakeMap Atlas is an openly available compilation of over 14,000 ShakeMaps of significant global earthquakes between 1900 and 2020. This revision includes: (1) the latest version of the ShakeMap software that provides refined uncertainty estimations and improved methods to combine macroseismic observations with updated ground-motion models; (2) an updated earthquake source catalog; (3) a refined strategy to select suites of prediction and conversion equations based on a new seismotectonic regionalization scheme; and (4) expanded macroseismic intensity and ground-motion datasets. We also tabulate reported economic losses and fatalities for Atlas events where such data are openly available. These changes make the new ShakeMap Atlas a self-consistent, calibrated catalog invaluable for investigating near-source ground motions, as well as seismic hazard, scenario, risk, and loss-model development and testing.","PeriodicalId":21687,"journal":{"name":"Seismological Research Letters","volume":"86 1-2","pages":""},"PeriodicalIF":3.3,"publicationDate":"2023-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139266358","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
L. Wotherspoon, Anna E. Kaiser, A. Stolte, E. Manea
This article presents the development of the site characterization database for the 2022 New Zealand National Seismic Hazard Model update. This database summarizes the site characterization parameters at past and present GeoNet seismic monitoring network instrument locations, including strong-motion, short-period, and broadband seismometer stations. Site characterization parameters required to assess and improve empirical ground-motion models and those used in codified seismic design frameworks internationally have been included in the database. Measurement uncertainty was assigned, and the quality of the data used to assign each parameter was classified. The site period (T0) was the most well constrained of all the site parameters, with almost half of the database classified based on high-quality measurements, with these dominated by microtremor-based horizontal-to-vertical spectral ratio. Although there was an improvement in the quality of the parameters representing the time-averaged shear-wave velocity in the uppermost 30 m of the profile (VS30), little site-specific data were available, with almost no information for rock sites. Most of these classifications were based on national maps or geologic interpretation. Depth-based parameters (Z1.0 and Z2.5) had the lowest quality overall, with very few direct measurements available to constrain these values. Despite these limitations, the quality of parameters assigned to instrument locations has improved and greatly expanded previous databases through the assignment of parameter values to the entire GeoNet seismic network.
{"title":"Development of the Site Characterization Database for the 2022 New Zealand National Seismic Hazard Model","authors":"L. Wotherspoon, Anna E. Kaiser, A. Stolte, E. Manea","doi":"10.1785/0220230219","DOIUrl":"https://doi.org/10.1785/0220230219","url":null,"abstract":"This article presents the development of the site characterization database for the 2022 New Zealand National Seismic Hazard Model update. This database summarizes the site characterization parameters at past and present GeoNet seismic monitoring network instrument locations, including strong-motion, short-period, and broadband seismometer stations. Site characterization parameters required to assess and improve empirical ground-motion models and those used in codified seismic design frameworks internationally have been included in the database. Measurement uncertainty was assigned, and the quality of the data used to assign each parameter was classified. The site period (T0) was the most well constrained of all the site parameters, with almost half of the database classified based on high-quality measurements, with these dominated by microtremor-based horizontal-to-vertical spectral ratio. Although there was an improvement in the quality of the parameters representing the time-averaged shear-wave velocity in the uppermost 30 m of the profile (VS30), little site-specific data were available, with almost no information for rock sites. Most of these classifications were based on national maps or geologic interpretation. Depth-based parameters (Z1.0 and Z2.5) had the lowest quality overall, with very few direct measurements available to constrain these values. Despite these limitations, the quality of parameters assigned to instrument locations has improved and greatly expanded previous databases through the assignment of parameter values to the entire GeoNet seismic network.","PeriodicalId":21687,"journal":{"name":"Seismological Research Letters","volume":"30 5","pages":""},"PeriodicalIF":3.3,"publicationDate":"2023-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139273863","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The earthquake that occurred near the city of Ston, Croatia, on 13 April 1850 is, together with the one from 1996, the strongest known event in the northwest part of the Dubrovnik epicentral area. This is the region with the highest seismic hazard in Croatia with a rich history of damaging earthquakes. Although listed in the relevant catalogs, this earthquake has never been addressed by a dedicated study. Herewith, we present analyses of a wealth of newly found material related to the damage and postearthquake actions of the authorities of the Province of Dalmatia, then a part of the Austrian Empire. We were able to estimate intensity at five localities, with a further six where the data were sufficient only to constrain the minimum intensity value. By far, most of the data refer to Ston and Dubrovnik. Intensity data points were inverted for the source parameters by two different methods, each of which yielded similar results. The focus is macroseismically located about 7 km east-southeast from Ston, at a depth of 9 km. Estimated epicentral intensity of 8.2 on the European macroseismic scale is equivalent to macroseismic local magnitude MmL=6.0 or the moment magnitude Mmw=5.9. The location of focus and the epicentral intensity are practically identical to those of the Ston–Slano earthquake of 1996. This is why we propose that these two earthquakes share the same composite seismogenic source consisting of a set of imbricated mostly reverse faults related to the basal thrust of the Dalmatian tectonic unit. The reliable location and quantification of the 1850 earthquake should contribute to a better understanding of the active dynamics of the set of large seismogenic faults in the Dubrovnik epicentral area.
{"title":"The Earthquake of 13 April 1850 near Ston, Croatia: Macroseismic Analyses","authors":"D. Herak, M. Herak, Iva Vrkić","doi":"10.1785/0220230299","DOIUrl":"https://doi.org/10.1785/0220230299","url":null,"abstract":"The earthquake that occurred near the city of Ston, Croatia, on 13 April 1850 is, together with the one from 1996, the strongest known event in the northwest part of the Dubrovnik epicentral area. This is the region with the highest seismic hazard in Croatia with a rich history of damaging earthquakes. Although listed in the relevant catalogs, this earthquake has never been addressed by a dedicated study. Herewith, we present analyses of a wealth of newly found material related to the damage and postearthquake actions of the authorities of the Province of Dalmatia, then a part of the Austrian Empire. We were able to estimate intensity at five localities, with a further six where the data were sufficient only to constrain the minimum intensity value. By far, most of the data refer to Ston and Dubrovnik. Intensity data points were inverted for the source parameters by two different methods, each of which yielded similar results. The focus is macroseismically located about 7 km east-southeast from Ston, at a depth of 9 km. Estimated epicentral intensity of 8.2 on the European macroseismic scale is equivalent to macroseismic local magnitude MmL=6.0 or the moment magnitude Mmw=5.9. The location of focus and the epicentral intensity are practically identical to those of the Ston–Slano earthquake of 1996. This is why we propose that these two earthquakes share the same composite seismogenic source consisting of a set of imbricated mostly reverse faults related to the basal thrust of the Dalmatian tectonic unit. The reliable location and quantification of the 1850 earthquake should contribute to a better understanding of the active dynamics of the set of large seismogenic faults in the Dubrovnik epicentral area.","PeriodicalId":21687,"journal":{"name":"Seismological Research Letters","volume":"2 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2023-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139273001","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Eduardo R. Diez Zaldivar, D. Sandron, Manuel Cutie Mustelier
Calibration of the local magnitude scale to match local tectonics is a key element in the development of research leading to seismic risk assessment and quantification of seismicity in active regions. In this study, we developed a local magnitude scale for the southeastern region of Cuba—the part of the island exposed to the greatest seismic hazard due to its proximity to the Oriente fault system. From the 2011–2021 Cuban catalog, 7750 earthquakes with ML>2 were selected, distributed in the region 19°–22° N, 73°–79° W, and recorded by at least four seismic stations (of the Cuban CW network) within 500 km of the hypocentre. The resulting input data set includes 33,916 amplitude measurements of the horizontal components. We set up the whole linear regression analysis procedure in the Matlab environment to obtain the formula for the local magnitude in the International Association of Seismology and Physics of the Earth’s Interior form. In a three-step procedure, we (1) removed the outliers; (2) searched for the parameters n, K, and Si that minimize the unbiased sample standard deviation of the residuals; and (3) set the anchor point for the parameter C. Thus, the new formula for the local magnitude ML is defined as follows: ML=log10(A)+1.000log10(R)+0.003R−1.963, in which A is the peak amplitude in nanometers simulated with a Wood–Anderson sensor, and R is the hypocentral distance in kilometers. We also calculated the station correction factors S for each station included in the analysis.
校准当地震级表，使其与当地构造相匹配，是开展地震风险评估和活跃地区地震量化研究的关键因素。在这项研究中，我们为古巴东南部地区制定了地方震级表--该地区因靠近 Oriente 断层系统而面临最大的地震风险。从 2011-2021 年古巴地震目录中选取了 7750 次震级大于 2 级的地震，这些地震分布在北纬 19°-22°、西经 73°-79°地区，并由距震中 500 公里范围内至少四个地震台（古巴 CW 网络）记录。由此得到的输入数据集包括 33,916 个水平分量的振幅测量值。我们在 Matlab 环境中设置了整个线性回归分析程序，以获得国际地震学和地球内部物理学协会表格中的当地震级公式。在三步程序中，我们：（1）剔除异常值；（2）寻找使残差的无偏样本标准偏差最小的参数 n、K 和 Si；（3）设置参数 C 的锚点：ML=log10(A)+1.000log10(R)+0.003R-1.963，其中 A 是用伍德-安德森传感器模拟的以纳米为单位的峰值振幅，R 是以公里为单位的次中心距离。我们还计算了分析中每个台站的台站校正因子 S。
{"title":"Calibration of the Local Magnitude Scale (ML) for Eastern Cuba","authors":"Eduardo R. Diez Zaldivar, D. Sandron, Manuel Cutie Mustelier","doi":"10.1785/0220230286","DOIUrl":"https://doi.org/10.1785/0220230286","url":null,"abstract":"Calibration of the local magnitude scale to match local tectonics is a key element in the development of research leading to seismic risk assessment and quantification of seismicity in active regions. In this study, we developed a local magnitude scale for the southeastern region of Cuba—the part of the island exposed to the greatest seismic hazard due to its proximity to the Oriente fault system. From the 2011–2021 Cuban catalog, 7750 earthquakes with ML>2 were selected, distributed in the region 19°–22° N, 73°–79° W, and recorded by at least four seismic stations (of the Cuban CW network) within 500 km of the hypocentre. The resulting input data set includes 33,916 amplitude measurements of the horizontal components. We set up the whole linear regression analysis procedure in the Matlab environment to obtain the formula for the local magnitude in the International Association of Seismology and Physics of the Earth’s Interior form. In a three-step procedure, we (1) removed the outliers; (2) searched for the parameters n, K, and Si that minimize the unbiased sample standard deviation of the residuals; and (3) set the anchor point for the parameter C. Thus, the new formula for the local magnitude ML is defined as follows: ML=log10(A)+1.000log10(R)+0.003R−1.963, in which A is the peak amplitude in nanometers simulated with a Wood–Anderson sensor, and R is the hypocentral distance in kilometers. We also calculated the station correction factors S for each station included in the analysis.","PeriodicalId":21687,"journal":{"name":"Seismological Research Letters","volume":"0 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2023-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139273459","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Kévin Juhel, Zacharie Duputel, Luis Rivera, Martin Vallée
Abstract In the minutes following a large earthquake, robust characterization of the seismic rupture can be obtained from full wavefield records at local distances or from early signals recorded by regional broadband seismometers. We focus here on the latter configuration, and evaluate the individual and joint performances of the early low-frequency elastic phases (W phase) and the recently discovered prompt elastogravity signals (PEGS). The 2011 Mw 9.1 Tohoku–Oki earthquake is a natural target for this evaluation, because the high quality of global and regional networks enabled to gather the best PEGS data set so far. We first confirm that the well-established W-phase method, using records from global seismological networks, is able to provide a reliable centroid moment tensor solution 22 min after the earthquake origin time. Using regional stations, an accurate W-phase solution can be obtained more rapidly, down to 10 min after origin time. On the other hand, a PEGS-based source inversion can provide even earlier, starting 3 min after origin time, a lower bound of the seismic moment (Mw 8.6) and constraints on the focal mechanism type. However, relying solely on PEGS introduces uncertainties caused by the hindering seismic noise and trade-offs between source parameters that limit the accuracy of source determination. We show that incorporating even a few early W phase signals to the PEGS data set reduces these uncertainties. Using more complete W phase and PEGS data sets available 5 min after origin time enables to converge towards a result close to the Global Centroid Moment Tensor solution.
{"title":"Early Source Characterization of Large Earthquakes Using <i>W</i> Phase and Prompt Elastogravity Signals","authors":"Kévin Juhel, Zacharie Duputel, Luis Rivera, Martin Vallée","doi":"10.1785/0220230195","DOIUrl":"https://doi.org/10.1785/0220230195","url":null,"abstract":"Abstract In the minutes following a large earthquake, robust characterization of the seismic rupture can be obtained from full wavefield records at local distances or from early signals recorded by regional broadband seismometers. We focus here on the latter configuration, and evaluate the individual and joint performances of the early low-frequency elastic phases (W phase) and the recently discovered prompt elastogravity signals (PEGS). The 2011 Mw 9.1 Tohoku–Oki earthquake is a natural target for this evaluation, because the high quality of global and regional networks enabled to gather the best PEGS data set so far. We first confirm that the well-established W-phase method, using records from global seismological networks, is able to provide a reliable centroid moment tensor solution 22 min after the earthquake origin time. Using regional stations, an accurate W-phase solution can be obtained more rapidly, down to 10 min after origin time. On the other hand, a PEGS-based source inversion can provide even earlier, starting 3 min after origin time, a lower bound of the seismic moment (Mw 8.6) and constraints on the focal mechanism type. However, relying solely on PEGS introduces uncertainties caused by the hindering seismic noise and trade-offs between source parameters that limit the accuracy of source determination. We show that incorporating even a few early W phase signals to the PEGS data set reduces these uncertainties. Using more complete W phase and PEGS data sets available 5 min after origin time enables to converge towards a result close to the Global Centroid Moment Tensor solution.","PeriodicalId":21687,"journal":{"name":"Seismological Research Letters","volume":"1 5","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134991692","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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