É. Beaucé, W. Frank, L. Seydoux, Piero Poli, Nathan Groebner, R. D. van der Hilst, Michel Campillo
We introduce BPMF (backprojection and matched filtering)—a complete and fully automated workflow designed for earthquake detection and location, and distributed in a Python package. This workflow enables the creation of comprehensive earthquake catalogs with low magnitudes of completeness using no or little prior knowledge of the study region. BPMF uses the seismic wavefield backprojection method to construct an initial earthquake catalog that is then densified with matched filtering. BPMF integrates recent machine learning tools to complement physics-based techniques, and improve the detection and location of earthquakes. In particular, BPMF offers a flexible framework in which machine learning detectors and backprojection can be harmoniously combined, effectively transforming single-station detectors into multistation detectors. The modularity of BPMF grants users the ability to control the contribution of machine learning tools within the workflow. The computation-intensive tasks (backprojection and matched filtering) are executed with C and CUDA-C routines wrapped in Python code. This leveraging of low-level, fast programming languages and graphic processing unit acceleration enables BPMF to efficiently handle large datasets. Here, we first summarize the methodology and describe the application programming interface. We then illustrate BPMF’s capabilities to characterize microseismicity with a 10 yr long application in the Ridgecrest, California area. Finally, we discuss the workflow’s runtime scaling with numerical resources and its versatility across various tectonic environments and different problems.
{"title":"BPMF: A Backprojection and Matched-Filtering Workflow for Automated Earthquake Detection and Location","authors":"É. Beaucé, W. Frank, L. Seydoux, Piero Poli, Nathan Groebner, R. D. van der Hilst, Michel Campillo","doi":"10.1785/0220230230","DOIUrl":"https://doi.org/10.1785/0220230230","url":null,"abstract":"\u0000 We introduce BPMF (backprojection and matched filtering)—a complete and fully automated workflow designed for earthquake detection and location, and distributed in a Python package. This workflow enables the creation of comprehensive earthquake catalogs with low magnitudes of completeness using no or little prior knowledge of the study region. BPMF uses the seismic wavefield backprojection method to construct an initial earthquake catalog that is then densified with matched filtering. BPMF integrates recent machine learning tools to complement physics-based techniques, and improve the detection and location of earthquakes. In particular, BPMF offers a flexible framework in which machine learning detectors and backprojection can be harmoniously combined, effectively transforming single-station detectors into multistation detectors. The modularity of BPMF grants users the ability to control the contribution of machine learning tools within the workflow. The computation-intensive tasks (backprojection and matched filtering) are executed with C and CUDA-C routines wrapped in Python code. This leveraging of low-level, fast programming languages and graphic processing unit acceleration enables BPMF to efficiently handle large datasets. Here, we first summarize the methodology and describe the application programming interface. We then illustrate BPMF’s capabilities to characterize microseismicity with a 10 yr long application in the Ridgecrest, California area. Finally, we discuss the workflow’s runtime scaling with numerical resources and its versatility across various tectonic environments and different problems.","PeriodicalId":21687,"journal":{"name":"Seismological Research Letters","volume":"40 14","pages":""},"PeriodicalIF":3.3,"publicationDate":"2023-12-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138602673","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}
Based on the advantages of the chaos particle swarm optimization algorithm and the generalized inversion technology, this article estimates the source parameters and site effects of the Wenchuan earthquake. We used 440 sets of strong-motion records obtained from 43 aftershocks, and the area covered by the records was divided into subregions A and B. Initial separation of source, path, and site from the seismic spectra of subregions A and B using generalized inversion technique and then the source-site optimization model is established using chaotic particle swarm technology. From path-corrected records, we obtained absolute site effects for 33 stations and equivalent source parameters for 43 earthquakes. We made the following conclusions: (1) The moment magnitude Mw was lower than the local magnitude MLdetermined by China Earthquake Network Center. The self-similarity of the Wenchuan earthquake was confirmed. The stress drop averaged 2.31 MPa, and it was independent of the magnitude size and focal depth. (2) In the frequency 1–10 Hz, the quality factor values in subregions A and B are 110.9f0.6 and 116.1f1.2. The decay rate of the crustal medium in the western region of the west Sichuan plateau is significant compared to the eastern part. (3) Bedrock stations 51MXT and L2007 have site effects within a certain frequency. The effect of slope topography on site predominant frequency is not apparent, and the site effects increase with the increase in elevation. The shape of the site amplification curve is more similar in the middle- and low-frequency bands, and different attenuation phenomena will appear in the high-frequency band.
{"title":"Estimation of Site Effects and Equivalent Source Parameters of Wenchuan Earthquake Based on Generalized Chaotic Particle Inversion Technique","authors":"Ke-Lin Chen, Xue-Liang Chen, Jingyan Lan, Li-Jun Qiu, Yi-Ling Zhu","doi":"10.1785/0220230028","DOIUrl":"https://doi.org/10.1785/0220230028","url":null,"abstract":"Based on the advantages of the chaos particle swarm optimization algorithm and the generalized inversion technology, this article estimates the source parameters and site effects of the Wenchuan earthquake. We used 440 sets of strong-motion records obtained from 43 aftershocks, and the area covered by the records was divided into subregions A and B. Initial separation of source, path, and site from the seismic spectra of subregions A and B using generalized inversion technique and then the source-site optimization model is established using chaotic particle swarm technology. From path-corrected records, we obtained absolute site effects for 33 stations and equivalent source parameters for 43 earthquakes. We made the following conclusions: (1) The moment magnitude Mw was lower than the local magnitude MLdetermined by China Earthquake Network Center. The self-similarity of the Wenchuan earthquake was confirmed. The stress drop averaged 2.31 MPa, and it was independent of the magnitude size and focal depth. (2) In the frequency 1–10 Hz, the quality factor values in subregions A and B are 110.9f0.6 and 116.1f1.2. The decay rate of the crustal medium in the western region of the west Sichuan plateau is significant compared to the eastern part. (3) Bedrock stations 51MXT and L2007 have site effects within a certain frequency. The effect of slope topography on site predominant frequency is not apparent, and the site effects increase with the increase in elevation. The shape of the site amplification curve is more similar in the middle- and low-frequency bands, and different attenuation phenomena will appear in the high-frequency band.","PeriodicalId":21687,"journal":{"name":"Seismological Research Letters","volume":"4 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2023-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139202592","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}
Sepideh J. Rastin, D. Rhoades, Chris Rollins, Matthew C. Gerstenberger
We propose a method to estimate the uncertainty of the average rate of earthquakes exceeding a magnitude threshold in a future period of given length based on observed variability of the earthquake process in an existing catalog. We estimate the ratio R of the variability to that of a stationary Poisson process. R is estimated from subsets of the catalog over a wide range of timescales. The method combines the epistemic uncertainty in estimating the rate from the catalog and the aleatory variability of the rate in future time periods. If R is stable over many timescales, there is a solid basis for estimating the uncertainty of earthquake rate estimates. In the 2022 revision of the New Zealand National Seismic Hazard Model (NZ NSHM), estimation of the total shallow earthquake rate over the next 100 yr and its uncertainty is an important element. Using a 70 yr New Zealand catalog with hypocentral depths ≤40 km and standardized magnitudes M ≥ 4.95, we find stable estimates of R for timescales from 3 days to 2.4 yr. This gives a standard error of 0.95 on the estimated annual rate of M ≥ 4.95, in the next 100 yr. R becomes unstable and has poor precision for longer subperiods. We investigate potential causes using synthetic catalogs with known inhomogeneities. Analysis of International Seismological Centre-Global Earthquake Model (ISC-GEM) catalog, to investigate the effect of higher magnitude thresholds, shows that R is lower for M ≥ 6.95 than for M ≥ 5.45. The ISC-GEM catalog restricted to New Zealand gives comparable stable estimates of R to the NZ NSHM 2022 catalog for M ≥ 5.45 and lower estimates than the NZ NSHM 2022 catalog for M ≥ 4.95. We also verify that magnitude standardization of the New Zealand GeoNet catalog has reduced the uncertainty of rate estimates by decreasing R throughout the entire range of timescales.
我们提出了一种方法，可以根据现有目录中观测到的地震过程的变异性，估算在未来给定长度的时期内超过震级阈值的地震平均发生率的不确定性。我们估算的是变异性与静止泊松过程的比率 R。R 是在广泛的时间尺度范围内根据目录子集估算出来的。该方法结合了从目录中估算比率的认识不确定性和未来时间段内比率的已知变异性。如果 R 在许多时间尺度上是稳定的，那么估算地震发生率估计值的不确定性就有了坚实的基础。在 2022 年对新西兰国家地震危险性模型（NZ NSHM）的修订中，估算未来 100 年的总浅层地震率及其不确定性是一项重要内容。使用新西兰 70 年的地震目录，低中心深度≤40 千米，标准化震级 M ≥4.95，我们发现在 3 天到 2.4 年的时间尺度内，R 的估计值比较稳定。对于更长的子周期，R 值变得不稳定，精度也很低。我们利用已知不均匀性的合成目录研究了潜在的原因。对国际地震中心-全球地震模型（ISC-GEM）震级目录的分析表明，M ≥ 6.95 时的 R 值低于 M ≥ 5.45 时的 R 值。局限于新西兰的ISC-GEM星表对M≥5.45的R的稳定估计值与NZ NSHM 2022星表相当，而对M≥4.95的R的估计值低于NZ NSHM 2022星表。我们还验证了新西兰 GeoNet 星表的震级标准化通过在整个时间尺度范围内降低 R 来减少速率估计值的不确定性。
{"title":"Estimation of Uncertainty in the Average Rate of Earthquakes Exceeding a Magnitude Threshold","authors":"Sepideh J. Rastin, D. Rhoades, Chris Rollins, Matthew C. Gerstenberger","doi":"10.1785/0220230242","DOIUrl":"https://doi.org/10.1785/0220230242","url":null,"abstract":"We propose a method to estimate the uncertainty of the average rate of earthquakes exceeding a magnitude threshold in a future period of given length based on observed variability of the earthquake process in an existing catalog. We estimate the ratio R of the variability to that of a stationary Poisson process. R is estimated from subsets of the catalog over a wide range of timescales. The method combines the epistemic uncertainty in estimating the rate from the catalog and the aleatory variability of the rate in future time periods. If R is stable over many timescales, there is a solid basis for estimating the uncertainty of earthquake rate estimates. In the 2022 revision of the New Zealand National Seismic Hazard Model (NZ NSHM), estimation of the total shallow earthquake rate over the next 100 yr and its uncertainty is an important element. Using a 70 yr New Zealand catalog with hypocentral depths ≤40 km and standardized magnitudes M ≥ 4.95, we find stable estimates of R for timescales from 3 days to 2.4 yr. This gives a standard error of 0.95 on the estimated annual rate of M ≥ 4.95, in the next 100 yr. R becomes unstable and has poor precision for longer subperiods. We investigate potential causes using synthetic catalogs with known inhomogeneities. Analysis of International Seismological Centre-Global Earthquake Model (ISC-GEM) catalog, to investigate the effect of higher magnitude thresholds, shows that R is lower for M ≥ 6.95 than for M ≥ 5.45. The ISC-GEM catalog restricted to New Zealand gives comparable stable estimates of R to the NZ NSHM 2022 catalog for M ≥ 5.45 and lower estimates than the NZ NSHM 2022 catalog for M ≥ 4.95. We also verify that magnitude standardization of the New Zealand GeoNet catalog has reduced the uncertainty of rate estimates by decreasing R throughout the entire range of timescales.","PeriodicalId":21687,"journal":{"name":"Seismological Research Letters","volume":"59 3 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2023-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139198090","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}
D. Wilson, C. R. Hutt, L. Gee, A. Ringler, R. Anthony
The U.S. Geological Survey (USGS) Global Seismographic Network (GSN) Program operates two thirds of the GSN, a network of state-of-the-art, digital seismological and geophysical sensors with digital telecommunications. This network serves as a multiuse scientific facility and a valuable resource for research, education, and monitoring. The other one third of the GSN is funded by the National Science Foundation (NSF), and the operations of this component are overseen by EarthScope. This collaboration between the USGS, EarthScope, and NSF has allowed for the development and operations of the GSN to be a truly multiuse network that provides near real-time open access data, facilitating fundamental discoveries by the Earth science community, supporting the earthquake hazards mission of the USGS, benefitting tsunami monitoring by the National Oceanic and Atmospheric Administration, and contributing to nuclear test monitoring and treaty verification. In this article, we describe the installation and evolution of the seismic networks operated by the USGS that ultimately led to the USGS portion of the GSN (100 stations under network codes IU, IC, and CU) as they are today and envision technological advances and opportunities to further improve the utility of the network in the future. This article focuses on the USGS-operated component of the GSN; a companion article on the GSN stations funded by the NSF and operated by the Cecil and Ida Green Institute of Geophysics and Planetary Physics, Scripps Institution of Oceanography, University of California at San Diego by Davis et al. (2023) appears in this volume.
美国地质调查局（USGS）的全球地震网络（GSN）计划运营着三分之二的全球地震网络，这是一个由最先进的数字地震和地球物理传感器以及数字通信组成的网络。该网络是一个多用途科学设施，也是研究、教育和监测的宝贵资源。全球地震台网的另外三分之一由美国国家科学基金会（NSF）资助，该部分的运行由地球观测站（EarthScope）负责监督。美国地质调查局、EarthScope 和美国国家科学基金会之间的合作使全球海洋观测网的开发和运行成为一个真正的多用途网络，提供近乎实时的开放数据，促进地球科学界的基础发现，支持美国地质调查局的地震灾害任务，有利于美国国家海洋和大气管理局的海啸监测，并有助于核试验监测和条约验证。在本文中，我们将介绍由美国地质调查局运营的地震台网的安装和演变过程，最终形成了今天的全球地震台网美国地质调查局部分（100 个台站，台网代码分别为 IU、IC 和 CU），并展望了未来进一步提高台网效用的技术进步和机遇。本文重点介绍全球海洋观测网中由美国地质调查局运营的部分；本卷还将刊载 Davis 等人（2023 年）撰写的关于由美国国家科学基金会资助、由加州大学圣地亚哥分校斯克里普斯海洋学研究所塞西尔和艾达-格林地球物理与行星物理研究所运营的全球海洋观测网台站的文章。
{"title":"Global Seismic Networks Operated by the U.S. Geological Survey","authors":"D. Wilson, C. R. Hutt, L. Gee, A. Ringler, R. Anthony","doi":"10.1785/0220230178","DOIUrl":"https://doi.org/10.1785/0220230178","url":null,"abstract":"The U.S. Geological Survey (USGS) Global Seismographic Network (GSN) Program operates two thirds of the GSN, a network of state-of-the-art, digital seismological and geophysical sensors with digital telecommunications. This network serves as a multiuse scientific facility and a valuable resource for research, education, and monitoring. The other one third of the GSN is funded by the National Science Foundation (NSF), and the operations of this component are overseen by EarthScope. This collaboration between the USGS, EarthScope, and NSF has allowed for the development and operations of the GSN to be a truly multiuse network that provides near real-time open access data, facilitating fundamental discoveries by the Earth science community, supporting the earthquake hazards mission of the USGS, benefitting tsunami monitoring by the National Oceanic and Atmospheric Administration, and contributing to nuclear test monitoring and treaty verification. In this article, we describe the installation and evolution of the seismic networks operated by the USGS that ultimately led to the USGS portion of the GSN (100 stations under network codes IU, IC, and CU) as they are today and envision technological advances and opportunities to further improve the utility of the network in the future. This article focuses on the USGS-operated component of the GSN; a companion article on the GSN stations funded by the NSF and operated by the Cecil and Ida Green Institute of Geophysics and Planetary Physics, Scripps Institution of Oceanography, University of California at San Diego by Davis et al. (2023) appears in this volume.","PeriodicalId":21687,"journal":{"name":"Seismological Research Letters","volume":"325 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2023-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139211206","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 6 February 2023 Türkiye earthquake doublet occurred on the east Anatolian fault system, which marks the tectonic boundary between the Arabia plate and the Anatolian microplate. This earthquake doublet consists of the Mw 7.8 Pazarcik earthquake along the east Anatolian fault and the Mw 7.6 Çardak earthquake along the Savrun–Çardak fault. Sentinel-1 Interferometric Synthetic Aperture Radar (InSAR) satellite successfully imaged the surface deformation caused by this earthquake doublet. The pixel offset from cross correlation of two Synthetic Aperture Radar images complements the interferograms in mapping the surface ruptures and the near-field deformation. We inverted for a coseismic slip model in elastic half-space using the InSAR phase and the range offset data. The variance reduction of the inversion reaches ∼90%. The coseismic slip model shows that the 2023 Türkiye earthquake doublet are left-lateral strike-slip events. The peak slip is located near Nurhak in southern Türkiye along the Savrun–Çardak fault. From measuring discontinuities in the pixel offset images we found that the surface rupture length of the Pazarcik earthquake is ∼300 km and the surface rupture length of the Çardak earthquake is ∼100 km. To first order, the faults are dipping vertically. “Slip gaps” are identified by our modeling, and they might be the source regions of future large earthquakes.
{"title":"Coseismic Deformation of the 2023 Türkiye Earthquake Doublet from Sentinel-1 InSAR and Implications for Earthquake Hazard","authors":"Xiaopeng Tong, Yongzhe Wang, Shi Chen","doi":"10.1785/0220230282","DOIUrl":"https://doi.org/10.1785/0220230282","url":null,"abstract":"The 6 February 2023 Türkiye earthquake doublet occurred on the east Anatolian fault system, which marks the tectonic boundary between the Arabia plate and the Anatolian microplate. This earthquake doublet consists of the Mw 7.8 Pazarcik earthquake along the east Anatolian fault and the Mw 7.6 Çardak earthquake along the Savrun–Çardak fault. Sentinel-1 Interferometric Synthetic Aperture Radar (InSAR) satellite successfully imaged the surface deformation caused by this earthquake doublet. The pixel offset from cross correlation of two Synthetic Aperture Radar images complements the interferograms in mapping the surface ruptures and the near-field deformation. We inverted for a coseismic slip model in elastic half-space using the InSAR phase and the range offset data. The variance reduction of the inversion reaches ∼90%. The coseismic slip model shows that the 2023 Türkiye earthquake doublet are left-lateral strike-slip events. The peak slip is located near Nurhak in southern Türkiye along the Savrun–Çardak fault. From measuring discontinuities in the pixel offset images we found that the surface rupture length of the Pazarcik earthquake is ∼300 km and the surface rupture length of the Çardak earthquake is ∼100 km. To first order, the faults are dipping vertically. “Slip gaps” are identified by our modeling, and they might be the source regions of future large earthquakes.","PeriodicalId":21687,"journal":{"name":"Seismological Research Letters","volume":"48 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2023-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139214762","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}
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}
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