Previous testing has shown that infrasound sensors deployed in the field can exhibit notable deviations from their nominal, lab-based calibrations. These variations may be due to changes in environmental conditions, long-term sensor drift, or other unresolved features. In early 2018, we installed two identical infrasound elements with five infrasound sensors at each element (Chaparral M50A, Chaparral M64LN, CEA/Martec MB2005, CEA/Seismowave MB3a, and Hyperion IFS-5113A). These sensors were accepted or under consideration for use in the International Monitoring System network of the Comprehensive Nuclear-Test-Ban Treaty. Each element had all sensors connected to a single digitizer and port to the atmosphere. We also recorded instrument enclosure air temperature and humidity and external air temperature. Using the MB2005 as the reference, we examine the relative sensor response (both magnitude and phase) as a function of time and frequency and compare it with quarterly laboratory calibrations and environmental conditions. We find that the magnitude response for all sensors exhibits some variability in both the lab and field, with the amplitude variations often >5%. The field-based variations are more severe and occur on both long-term (months) and short-term (hours) timescales. Short-term variability correlates with changes in environmental conditions and is considerable (up to 25%) for the Chaparral M50A and noticeable (∼5%) for the French Alternative Energies and Atomic Energy Commission (CEA) MB3a. Long-term magnitude variability for the Chaparral M50A was up to 50% and does not clearly correlate with environmental conditions. The other sensors show some long-term magnitude offsets, but they have relatively stable responses in the conditions we examined. The MB3a also displays some frequency-dependent magnitude variability and shows a minor dependence on temperature. Phase estimates are stable and near zero for all sensors tested. These results strongly suggest sensor response and variability due to environmental conditions should be considered in future infrasound data interpretation and sensor selection and development.
{"title":"Long-Term Infrasound Sensor Calibration and Characterization","authors":"David Fee, B. Merchant","doi":"10.1785/0220230347","DOIUrl":"https://doi.org/10.1785/0220230347","url":null,"abstract":"\u0000 Previous testing has shown that infrasound sensors deployed in the field can exhibit notable deviations from their nominal, lab-based calibrations. These variations may be due to changes in environmental conditions, long-term sensor drift, or other unresolved features. In early 2018, we installed two identical infrasound elements with five infrasound sensors at each element (Chaparral M50A, Chaparral M64LN, CEA/Martec MB2005, CEA/Seismowave MB3a, and Hyperion IFS-5113A). These sensors were accepted or under consideration for use in the International Monitoring System network of the Comprehensive Nuclear-Test-Ban Treaty. Each element had all sensors connected to a single digitizer and port to the atmosphere. We also recorded instrument enclosure air temperature and humidity and external air temperature. Using the MB2005 as the reference, we examine the relative sensor response (both magnitude and phase) as a function of time and frequency and compare it with quarterly laboratory calibrations and environmental conditions. We find that the magnitude response for all sensors exhibits some variability in both the lab and field, with the amplitude variations often >5%. The field-based variations are more severe and occur on both long-term (months) and short-term (hours) timescales. Short-term variability correlates with changes in environmental conditions and is considerable (up to 25%) for the Chaparral M50A and noticeable (∼5%) for the French Alternative Energies and Atomic Energy Commission (CEA) MB3a. Long-term magnitude variability for the Chaparral M50A was up to 50% and does not clearly correlate with environmental conditions. The other sensors show some long-term magnitude offsets, but they have relatively stable responses in the conditions we examined. The MB3a also displays some frequency-dependent magnitude variability and shows a minor dependence on temperature. Phase estimates are stable and near zero for all sensors tested. These results strongly suggest sensor response and variability due to environmental conditions should be considered in future infrasound data interpretation and sensor selection and development.","PeriodicalId":21687,"journal":{"name":"Seismological Research Letters","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2024-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139859220","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 dispersive nature of surface waves can be used for shear-wave velocity inversion at different scales. We show that four large earthquakes from the 2023 Türkiye earthquake sequence generate visible surface waves recorded by a dense strong-motion network deployed along the Dead Sea Transform (DST) in Israel. Thanks to favorable geometrical conditions and source radiation patterns, we observe both Rayleigh and Love waves that travel predominantly parallel to the network. We can reliably compute the dispersion of three Love-wave modes and two Rayleigh-wave modes. Using these dispersion curves, we invert for a 1D S-wave velocity model of the entire DST, outperforming an existing model. Statistical and kernel sensitivity analysis show high certainty down to a depth of 30 km thanks to the multimode joint inversion in the frequency band of 0.03–0.3 Hz. Using a multiwindow approach, we invert for an along-strike laterally varying velocity model of the DST. Although it is limited to the fundamental Love-wave mode, using the 1D model as a constraint allows us to recover a shallow (10 km) velocity structure in agreement with previous studies of the area. Despite the simplicity of our used approach, it can be used as a basis for more advanced studies.
面波的色散特性可用于不同尺度的剪切波速度反演。我们展示了 2023 年图尔基耶地震序列中的四次大地震产生的可见面波，该面波由沿以色列死海转换（DST）部署的密集强震网络记录。得益于有利的几何条件和震源辐射模式，我们观测到了主要平行于网络传播的瑞利波和爱波。我们可以可靠地计算出三种爱波模式和两种瑞利波模式的频散曲线。利用这些频散曲线，我们反演了整个 DST 的一维 S 波速度模型，结果优于现有模型。统计和核敏感性分析表明，由于在 0.03-0.3 Hz 频率带进行了多模联合反演，深度达 30 km 的确定性很高。利用多窗口方法，我们反演了 DST 的沿线横向变化速度模型。虽然仅限于基本的爱波模式，但以一维模型为约束，我们可以恢复出一个浅层（10 公里）的速度结构，这与该地区以前的研究结果是一致的。尽管我们使用的方法很简单，但它可以作为更高级研究的基础。
{"title":"Shear-Wave Velocity Model for the Dead Sea Transform from Multimode Inversion of Surface Waves Excited by the February 2023 Southeast Türkiye Earthquake Sequence","authors":"A. Lellouch, A. Inbal, A. Ziv","doi":"10.1785/0220230303","DOIUrl":"https://doi.org/10.1785/0220230303","url":null,"abstract":"\u0000 The dispersive nature of surface waves can be used for shear-wave velocity inversion at different scales. We show that four large earthquakes from the 2023 Türkiye earthquake sequence generate visible surface waves recorded by a dense strong-motion network deployed along the Dead Sea Transform (DST) in Israel. Thanks to favorable geometrical conditions and source radiation patterns, we observe both Rayleigh and Love waves that travel predominantly parallel to the network. We can reliably compute the dispersion of three Love-wave modes and two Rayleigh-wave modes. Using these dispersion curves, we invert for a 1D S-wave velocity model of the entire DST, outperforming an existing model. Statistical and kernel sensitivity analysis show high certainty down to a depth of 30 km thanks to the multimode joint inversion in the frequency band of 0.03–0.3 Hz. Using a multiwindow approach, we invert for an along-strike laterally varying velocity model of the DST. Although it is limited to the fundamental Love-wave mode, using the 1D model as a constraint allows us to recover a shallow (10 km) velocity structure in agreement with previous studies of the area. Despite the simplicity of our used approach, it can be used as a basis for more advanced studies.","PeriodicalId":21687,"journal":{"name":"Seismological Research Letters","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2024-02-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139810140","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}
Niranjan Joshi, Roland Roberts, Ari Tryggvason, Björn Lund
We investigate changes in the global reported fatalities from earthquake disasters in the global Emergency Events Database (EM-DAT). Drawing parallels with the Gutenberg–Richter frequency–magnitude analysis, in terms of disaster frequency versus the number of casualties, we see a significant overlap of the curves and improving levels of completeness over six 20-year periods. This implies a decrease in underreporting with time. We find that the apparent strong upward trend in the number of (reported) earthquake disasters in EM-DAT is caused by a gradually improved reporting primarily of events killing fewer than 10 people. Our findings imply that the true (reported and unreported) number of earthquake disasters, according to the EM-DAT definition, has been surprisingly constant over, at least, the last 100 yr. We also show that the average annual number of people killed in earthquake disasters is relatively unaffected by spurious trends in reporting and has remained remarkably constant despite population increase. This implies an impressive reduced mortality risk roughly proportional to population increase since 1900. However, there is no indication in the data that the risk of future mega-disasters is negligible, and further major reductions in vulnerability should be actively pursued.
{"title":"Earthquake Disaster Fatality Data: Temporally Stable Power Law Behavior and Effects of Underreporting","authors":"Niranjan Joshi, Roland Roberts, Ari Tryggvason, Björn Lund","doi":"10.1785/0220230342","DOIUrl":"https://doi.org/10.1785/0220230342","url":null,"abstract":"\u0000 We investigate changes in the global reported fatalities from earthquake disasters in the global Emergency Events Database (EM-DAT). Drawing parallels with the Gutenberg–Richter frequency–magnitude analysis, in terms of disaster frequency versus the number of casualties, we see a significant overlap of the curves and improving levels of completeness over six 20-year periods. This implies a decrease in underreporting with time. We find that the apparent strong upward trend in the number of (reported) earthquake disasters in EM-DAT is caused by a gradually improved reporting primarily of events killing fewer than 10 people. Our findings imply that the true (reported and unreported) number of earthquake disasters, according to the EM-DAT definition, has been surprisingly constant over, at least, the last 100 yr. We also show that the average annual number of people killed in earthquake disasters is relatively unaffected by spurious trends in reporting and has remained remarkably constant despite population increase. This implies an impressive reduced mortality risk roughly proportional to population increase since 1900. However, there is no indication in the data that the risk of future mega-disasters is negligible, and further major reductions in vulnerability should be actively pursued.","PeriodicalId":21687,"journal":{"name":"Seismological Research Letters","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2024-02-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139811149","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}
Jiangnan Lin, Wenbin Jiang, Yong Zhou, Bin Liu, Minghui Zhao, Zhuo Xiao, Lingmin Cao, Min Xu
Urban seismology has recently emerged as a vibrant scientific field, driven by the growing interest in seismic signals generated by major public events, sports gatherings, and transportation services. However, deploying dense traditional seismometers in economically active, densely populated urban areas with heavy traffic poses significant challenges. In this study, we conducted a field experiment utilizing distributed acoustic sensing (DAS) technology during a fireworks display in Guangzhou on 5 February 2023. About 572 m of optical fiber was turned into 286 seismic sensors and deployed on LingShan Island to monitor various vibration signals generated during the fireworks show. Our analysis revealed substantial correlations between crowd motions during different phases of the event and ambient noise features recorded by DAS. Moreover, the cross-correlation functions of the ambient noise with its dispersion characteristics pointed to near-field pedestrian activity as the primary noise source. Real-time heat maps of human crowd motions were reconstructed from DAS recording, offering significant insights into the variations of activity intensity across different locations. Discerning fireworks events on the DAS array is more effective than on a scattered seismometer array, because it is easier to ensure that the same event is picked for all the sites in the DAS dense linear configuration. The DAS data inspection allowed us to pick up a total of 549 firecracker explosions in comparison to the seismometer data that only allowed us to detect 116 firecracker events. The heights of fireworks were located by the grid-search method and predominantly distributed at 75–300 m, closely aligning with actual fireworks explosion locations. Our findings underscore that the DAS technology can monitor crowd motion and detect vibration signals in the air, bridging the gap between fundamental earth science research and human social activities.
最近，随着人们对重大公共活动、体育集会和交通服务产生的地震信号的兴趣日益浓厚，城市地震学已成为一个充满活力的科学领域。然而，在经济活跃、人口稠密、交通繁忙的城市地区部署密集的传统地震仪是一项重大挑战。在本研究中，我们利用分布式声学传感（DAS）技术在 2023 年 2 月 5 日广州烟花汇演期间进行了现场实验。约 572 米长的光纤被改造成 286 个地震传感器，部署在灵山岛上，用于监测烟花表演期间产生的各种振动信号。我们的分析表明，活动不同阶段的人群运动与 DAS 记录的环境噪声特征之间存在很大的相关性。此外，环境噪声与其扩散特征的交叉相关函数表明，近场行人活动是主要的噪声源。通过 DAS 记录重建了人群运动的实时热图，为了解不同地点的活动强度变化提供了重要依据。在 DAS 阵列上分辨烟花事件比在散布式地震仪阵列上分辨烟花事件更有效，因为在 DAS 密集线性配置中，更容易确保在所有地点选取相同的事件。通过 DAS 数据检查，我们总共发现了 549 次爆竹爆炸事件，而地震仪数据只能发现 116 次爆竹事件。烟花的高度是通过网格搜索法确定的，主要分布在 75-300 米处，与实际烟花爆炸位置非常吻合。我们的研究结果表明，DAS 技术可以监测人群运动并探测空气中的振动信号，在地球科学基础研究与人类社会活动之间架起了一座桥梁。
{"title":"Distributed Acoustic Sensing for Crowd Motion and Firecracker Explosions in the Fireworks Show","authors":"Jiangnan Lin, Wenbin Jiang, Yong Zhou, Bin Liu, Minghui Zhao, Zhuo Xiao, Lingmin Cao, Min Xu","doi":"10.1785/0220230346","DOIUrl":"https://doi.org/10.1785/0220230346","url":null,"abstract":"\u0000 Urban seismology has recently emerged as a vibrant scientific field, driven by the growing interest in seismic signals generated by major public events, sports gatherings, and transportation services. However, deploying dense traditional seismometers in economically active, densely populated urban areas with heavy traffic poses significant challenges. In this study, we conducted a field experiment utilizing distributed acoustic sensing (DAS) technology during a fireworks display in Guangzhou on 5 February 2023. About 572 m of optical fiber was turned into 286 seismic sensors and deployed on LingShan Island to monitor various vibration signals generated during the fireworks show. Our analysis revealed substantial correlations between crowd motions during different phases of the event and ambient noise features recorded by DAS. Moreover, the cross-correlation functions of the ambient noise with its dispersion characteristics pointed to near-field pedestrian activity as the primary noise source. Real-time heat maps of human crowd motions were reconstructed from DAS recording, offering significant insights into the variations of activity intensity across different locations. Discerning fireworks events on the DAS array is more effective than on a scattered seismometer array, because it is easier to ensure that the same event is picked for all the sites in the DAS dense linear configuration. The DAS data inspection allowed us to pick up a total of 549 firecracker explosions in comparison to the seismometer data that only allowed us to detect 116 firecracker events. The heights of fireworks were located by the grid-search method and predominantly distributed at 75–300 m, closely aligning with actual fireworks explosion locations. Our findings underscore that the DAS technology can monitor crowd motion and detect vibration signals in the air, bridging the gap between fundamental earth science research and human social activities.","PeriodicalId":21687,"journal":{"name":"Seismological Research Letters","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2024-02-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139870131","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}
Geodetic strain rate characterizes present-day crustal deformation and therefore may be used as a spatial predictor for earthquakes. However, the reported correlation between strain rates and seismicity varies significantly in different places. Here, we systematically study the correlation between strain rate, seismicity, and seismic moment in six regions representing typical plate boundary zones, diffuse plate boundary regions, and continental interiors. We quantify the strain rate–seismicity correlation using a method similar to the Molchan error diagram and area skill scores. We find that the correlation between strain rate and seismicity varies with different tectonic settings that can be characterized by the mean strain rates. Strong correlations are found in typical plate boundary zones where strain rates are high and concentrated at major fault zones, whereas poor or no correlations are found in stable continental interiors with low strain rates. The correlation between strain rate and seismicity is also time dependent: It is stronger in seismically active periods but weaker during periods of relative quiescence. These temporal variations can be useful for hazard assessment.
{"title":"Correlation between Strain Rate and Seismicity in Different Tectonic Settings","authors":"Yuxuan Chen, Mian Liu","doi":"10.1785/0220230306","DOIUrl":"https://doi.org/10.1785/0220230306","url":null,"abstract":"\u0000 Geodetic strain rate characterizes present-day crustal deformation and therefore may be used as a spatial predictor for earthquakes. However, the reported correlation between strain rates and seismicity varies significantly in different places. Here, we systematically study the correlation between strain rate, seismicity, and seismic moment in six regions representing typical plate boundary zones, diffuse plate boundary regions, and continental interiors. We quantify the strain rate–seismicity correlation using a method similar to the Molchan error diagram and area skill scores. We find that the correlation between strain rate and seismicity varies with different tectonic settings that can be characterized by the mean strain rates. Strong correlations are found in typical plate boundary zones where strain rates are high and concentrated at major fault zones, whereas poor or no correlations are found in stable continental interiors with low strain rates. The correlation between strain rate and seismicity is also time dependent: It is stronger in seismically active periods but weaker during periods of relative quiescence. These temporal variations can be useful for hazard assessment.","PeriodicalId":21687,"journal":{"name":"Seismological Research Letters","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2024-02-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139868983","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}
Voon Hui Lai, Kathleen M. Hodgkinson, R. Porritt, R. Mellors
With increasing geophysical applications using distributed acoustic sensing (DAS) technology, there is a need to implement a metadata standard specifically for DAS to facilitate the integration of DAS measurements across experiments and increase reusability. We propose a metadata standard intended primarily for the DAS research community, which fully describes the five key components of a DAS experiment: (1) interrogator; (2) data acquisition; (3) channels; (4) cable; and (5) fiber. The proposed metadata schema, which is the overall structure of the metadata, is hierarchical based, with a parent “overview” metadata block describing the experiment, and two main child branches describing the instrument (i.e., interrogator, photonics setup, and acquisition parameters) and the sensor locations (i.e., cable installation and fiber properties). The metadata schema is designed to be independent of the time-series data so that corrections and updates can be applied to the metadata without having to manipulate large volumes of time-series data. Unique identifiers are used as pointers that map different components within the metadata schema; they also provide a natural basis for the naming convention (i.e., source identifier) of the time-series data in which the time series can be described using identifiers defined by the metadata standard. We advocate for the metadata to be stored in a separate structure from the data itself. The metadata standard is successfully applied to four common scenarios: horizontal direct buried cable, dark fiber, borehole cable, and active survey, and two hypothetical scenarios: multiple interrogators to a single cable, and a single interrogator to multiple cables. Finally, we use GitHub to implement version control for the metadata standard, to enable community collaboration and facilitate sustainable development of the metadata standard, as the DAS technology and application continue to evolve.
随着使用分布式声学传感（DAS）技术的地球物理应用越来越多，有必要专门针对 DAS 实施元数据标准，以促进 DAS 测量在不同实验中的整合并提高可重用性。我们提出的元数据标准主要面向 DAS 研究界，全面描述了 DAS 实验的五个关键组成部分：(1) 询问器；(2) 数据采集；(3) 信道；(4) 电缆；(5) 光纤。拟议的元数据模式是元数据的整体结构，采用分层结构，其父 "概述 "元数据块描述实验，两个主要子分支分别描述仪器（即询问器、光子学设置和采集参数）和传感器位置（即电缆安装和光纤属性）。元数据模式的设计独立于时间序列数据，因此可以对元数据进行修正和更新，而无需处理大量的时间序列数据。独一无二的标识符可作为指针，映射元数据模式中的不同组件；它们还为时间序列数据的命名约定（即源标识符）提供了一个自然基础，其中的时间序列可使用元数据标准定义的标识符进行描述。我们主张将元数据与数据本身分开存储。元数据标准被成功应用于四种常见场景：水平直埋光缆、暗光纤、井眼光缆和主动勘测，以及两种假设场景：多个询问器连接单根光缆和单个询问器连接多根光缆。最后，随着 DAS 技术和应用的不断发展，我们使用 GitHub 对元数据标准实施版本控制，以实现社区协作，促进元数据标准的可持续发展。
{"title":"Toward a Metadata Standard for Distributed Acoustic Sensing (DAS) Data Collection","authors":"Voon Hui Lai, Kathleen M. Hodgkinson, R. Porritt, R. Mellors","doi":"10.1785/0220230325","DOIUrl":"https://doi.org/10.1785/0220230325","url":null,"abstract":"\u0000 With increasing geophysical applications using distributed acoustic sensing (DAS) technology, there is a need to implement a metadata standard specifically for DAS to facilitate the integration of DAS measurements across experiments and increase reusability. We propose a metadata standard intended primarily for the DAS research community, which fully describes the five key components of a DAS experiment: (1) interrogator; (2) data acquisition; (3) channels; (4) cable; and (5) fiber. The proposed metadata schema, which is the overall structure of the metadata, is hierarchical based, with a parent “overview” metadata block describing the experiment, and two main child branches describing the instrument (i.e., interrogator, photonics setup, and acquisition parameters) and the sensor locations (i.e., cable installation and fiber properties). The metadata schema is designed to be independent of the time-series data so that corrections and updates can be applied to the metadata without having to manipulate large volumes of time-series data. Unique identifiers are used as pointers that map different components within the metadata schema; they also provide a natural basis for the naming convention (i.e., source identifier) of the time-series data in which the time series can be described using identifiers defined by the metadata standard. We advocate for the metadata to be stored in a separate structure from the data itself. The metadata standard is successfully applied to four common scenarios: horizontal direct buried cable, dark fiber, borehole cable, and active survey, and two hypothetical scenarios: multiple interrogators to a single cable, and a single interrogator to multiple cables. Finally, we use GitHub to implement version control for the metadata standard, to enable community collaboration and facilitate sustainable development of the metadata standard, as the DAS technology and application continue to evolve.","PeriodicalId":21687,"journal":{"name":"Seismological Research Letters","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2024-02-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139869117","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}
Niranjan Joshi, Roland Roberts, Ari Tryggvason, Björn Lund
We investigate changes in the global reported fatalities from earthquake disasters in the global Emergency Events Database (EM-DAT). Drawing parallels with the Gutenberg–Richter frequency–magnitude analysis, in terms of disaster frequency versus the number of casualties, we see a significant overlap of the curves and improving levels of completeness over six 20-year periods. This implies a decrease in underreporting with time. We find that the apparent strong upward trend in the number of (reported) earthquake disasters in EM-DAT is caused by a gradually improved reporting primarily of events killing fewer than 10 people. Our findings imply that the true (reported and unreported) number of earthquake disasters, according to the EM-DAT definition, has been surprisingly constant over, at least, the last 100 yr. We also show that the average annual number of people killed in earthquake disasters is relatively unaffected by spurious trends in reporting and has remained remarkably constant despite population increase. This implies an impressive reduced mortality risk roughly proportional to population increase since 1900. However, there is no indication in the data that the risk of future mega-disasters is negligible, and further major reductions in vulnerability should be actively pursued.
{"title":"Earthquake Disaster Fatality Data: Temporally Stable Power Law Behavior and Effects of Underreporting","authors":"Niranjan Joshi, Roland Roberts, Ari Tryggvason, Björn Lund","doi":"10.1785/0220230342","DOIUrl":"https://doi.org/10.1785/0220230342","url":null,"abstract":"\u0000 We investigate changes in the global reported fatalities from earthquake disasters in the global Emergency Events Database (EM-DAT). Drawing parallels with the Gutenberg–Richter frequency–magnitude analysis, in terms of disaster frequency versus the number of casualties, we see a significant overlap of the curves and improving levels of completeness over six 20-year periods. This implies a decrease in underreporting with time. We find that the apparent strong upward trend in the number of (reported) earthquake disasters in EM-DAT is caused by a gradually improved reporting primarily of events killing fewer than 10 people. Our findings imply that the true (reported and unreported) number of earthquake disasters, according to the EM-DAT definition, has been surprisingly constant over, at least, the last 100 yr. We also show that the average annual number of people killed in earthquake disasters is relatively unaffected by spurious trends in reporting and has remained remarkably constant despite population increase. This implies an impressive reduced mortality risk roughly proportional to population increase since 1900. However, there is no indication in the data that the risk of future mega-disasters is negligible, and further major reductions in vulnerability should be actively pursued.","PeriodicalId":21687,"journal":{"name":"Seismological Research Letters","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2024-02-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139870852","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}
Jiangnan Lin, Wenbin Jiang, Yong Zhou, Bin Liu, Minghui Zhao, Zhuo Xiao, Lingmin Cao, Min Xu
Urban seismology has recently emerged as a vibrant scientific field, driven by the growing interest in seismic signals generated by major public events, sports gatherings, and transportation services. However, deploying dense traditional seismometers in economically active, densely populated urban areas with heavy traffic poses significant challenges. In this study, we conducted a field experiment utilizing distributed acoustic sensing (DAS) technology during a fireworks display in Guangzhou on 5 February 2023. About 572 m of optical fiber was turned into 286 seismic sensors and deployed on LingShan Island to monitor various vibration signals generated during the fireworks show. Our analysis revealed substantial correlations between crowd motions during different phases of the event and ambient noise features recorded by DAS. Moreover, the cross-correlation functions of the ambient noise with its dispersion characteristics pointed to near-field pedestrian activity as the primary noise source. Real-time heat maps of human crowd motions were reconstructed from DAS recording, offering significant insights into the variations of activity intensity across different locations. Discerning fireworks events on the DAS array is more effective than on a scattered seismometer array, because it is easier to ensure that the same event is picked for all the sites in the DAS dense linear configuration. The DAS data inspection allowed us to pick up a total of 549 firecracker explosions in comparison to the seismometer data that only allowed us to detect 116 firecracker events. The heights of fireworks were located by the grid-search method and predominantly distributed at 75–300 m, closely aligning with actual fireworks explosion locations. Our findings underscore that the DAS technology can monitor crowd motion and detect vibration signals in the air, bridging the gap between fundamental earth science research and human social activities.
最近，随着人们对重大公共活动、体育集会和交通服务产生的地震信号的兴趣日益浓厚，城市地震学已成为一个充满活力的科学领域。然而，在经济活跃、人口稠密、交通繁忙的城市地区部署密集的传统地震仪是一项重大挑战。在本研究中，我们利用分布式声学传感（DAS）技术在 2023 年 2 月 5 日广州烟花汇演期间进行了现场实验。约 572 米长的光纤被改造成 286 个地震传感器，部署在灵山岛上，用于监测烟花表演期间产生的各种振动信号。我们的分析表明，活动不同阶段的人群运动与 DAS 记录的环境噪声特征之间存在很大的相关性。此外，环境噪声与其扩散特征的交叉相关函数表明，近场行人活动是主要的噪声源。通过 DAS 记录重建了人群运动的实时热图，为了解不同地点的活动强度变化提供了重要依据。在 DAS 阵列上分辨烟花事件比在散布式地震仪阵列上分辨烟花事件更有效，因为在 DAS 密集线性配置中，更容易确保在所有地点选取相同的事件。通过 DAS 数据检查，我们总共发现了 549 次爆竹爆炸事件，而地震仪数据只能发现 116 次爆竹事件。烟花的高度是通过网格搜索法确定的，主要分布在 75-300 米处，与实际烟花爆炸位置非常吻合。我们的研究结果表明，DAS 技术可以监测人群运动并探测空气中的振动信号，在地球科学基础研究与人类社会活动之间架起了一座桥梁。
{"title":"Distributed Acoustic Sensing for Crowd Motion and Firecracker Explosions in the Fireworks Show","authors":"Jiangnan Lin, Wenbin Jiang, Yong Zhou, Bin Liu, Minghui Zhao, Zhuo Xiao, Lingmin Cao, Min Xu","doi":"10.1785/0220230346","DOIUrl":"https://doi.org/10.1785/0220230346","url":null,"abstract":"\u0000 Urban seismology has recently emerged as a vibrant scientific field, driven by the growing interest in seismic signals generated by major public events, sports gatherings, and transportation services. However, deploying dense traditional seismometers in economically active, densely populated urban areas with heavy traffic poses significant challenges. In this study, we conducted a field experiment utilizing distributed acoustic sensing (DAS) technology during a fireworks display in Guangzhou on 5 February 2023. About 572 m of optical fiber was turned into 286 seismic sensors and deployed on LingShan Island to monitor various vibration signals generated during the fireworks show. Our analysis revealed substantial correlations between crowd motions during different phases of the event and ambient noise features recorded by DAS. Moreover, the cross-correlation functions of the ambient noise with its dispersion characteristics pointed to near-field pedestrian activity as the primary noise source. Real-time heat maps of human crowd motions were reconstructed from DAS recording, offering significant insights into the variations of activity intensity across different locations. Discerning fireworks events on the DAS array is more effective than on a scattered seismometer array, because it is easier to ensure that the same event is picked for all the sites in the DAS dense linear configuration. The DAS data inspection allowed us to pick up a total of 549 firecracker explosions in comparison to the seismometer data that only allowed us to detect 116 firecracker events. The heights of fireworks were located by the grid-search method and predominantly distributed at 75–300 m, closely aligning with actual fireworks explosion locations. Our findings underscore that the DAS technology can monitor crowd motion and detect vibration signals in the air, bridging the gap between fundamental earth science research and human social activities.","PeriodicalId":21687,"journal":{"name":"Seismological Research Letters","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2024-02-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139810323","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 dispersive nature of surface waves can be used for shear-wave velocity inversion at different scales. We show that four large earthquakes from the 2023 Türkiye earthquake sequence generate visible surface waves recorded by a dense strong-motion network deployed along the Dead Sea Transform (DST) in Israel. Thanks to favorable geometrical conditions and source radiation patterns, we observe both Rayleigh and Love waves that travel predominantly parallel to the network. We can reliably compute the dispersion of three Love-wave modes and two Rayleigh-wave modes. Using these dispersion curves, we invert for a 1D S-wave velocity model of the entire DST, outperforming an existing model. Statistical and kernel sensitivity analysis show high certainty down to a depth of 30 km thanks to the multimode joint inversion in the frequency band of 0.03–0.3 Hz. Using a multiwindow approach, we invert for an along-strike laterally varying velocity model of the DST. Although it is limited to the fundamental Love-wave mode, using the 1D model as a constraint allows us to recover a shallow (10 km) velocity structure in agreement with previous studies of the area. Despite the simplicity of our used approach, it can be used as a basis for more advanced studies.
面波的色散特性可用于不同尺度的剪切波速度反演。我们展示了 2023 年图尔基耶地震序列中的四次大地震产生的可见面波，该面波由沿以色列死海转换（DST）部署的密集强震网络记录。得益于有利的几何条件和震源辐射模式，我们观测到了主要平行于网络传播的瑞利波和爱波。我们可以可靠地计算出三种爱波模式和两种瑞利波模式的频散曲线。利用这些频散曲线，我们反演了整个 DST 的一维 S 波速度模型，结果优于现有模型。统计和核敏感性分析表明，由于在 0.03-0.3 Hz 频率带进行了多模联合反演，深度达 30 km 的确定性很高。利用多窗口方法，我们反演了 DST 的沿线横向变化速度模型。虽然仅限于基本的爱波模式，但以一维模型为约束，我们可以恢复出一个浅层（10 公里）的速度结构，这与该地区以前的研究结果是一致的。尽管我们使用的方法很简单，但它可以作为更高级研究的基础。
{"title":"Shear-Wave Velocity Model for the Dead Sea Transform from Multimode Inversion of Surface Waves Excited by the February 2023 Southeast Türkiye Earthquake Sequence","authors":"A. Lellouch, A. Inbal, A. Ziv","doi":"10.1785/0220230303","DOIUrl":"https://doi.org/10.1785/0220230303","url":null,"abstract":"\u0000 The dispersive nature of surface waves can be used for shear-wave velocity inversion at different scales. We show that four large earthquakes from the 2023 Türkiye earthquake sequence generate visible surface waves recorded by a dense strong-motion network deployed along the Dead Sea Transform (DST) in Israel. Thanks to favorable geometrical conditions and source radiation patterns, we observe both Rayleigh and Love waves that travel predominantly parallel to the network. We can reliably compute the dispersion of three Love-wave modes and two Rayleigh-wave modes. Using these dispersion curves, we invert for a 1D S-wave velocity model of the entire DST, outperforming an existing model. Statistical and kernel sensitivity analysis show high certainty down to a depth of 30 km thanks to the multimode joint inversion in the frequency band of 0.03–0.3 Hz. Using a multiwindow approach, we invert for an along-strike laterally varying velocity model of the DST. Although it is limited to the fundamental Love-wave mode, using the 1D model as a constraint allows us to recover a shallow (10 km) velocity structure in agreement with previous studies of the area. Despite the simplicity of our used approach, it can be used as a basis for more advanced studies.","PeriodicalId":21687,"journal":{"name":"Seismological Research Letters","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2024-02-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139869869","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}
Voon Hui Lai, Kathleen M. Hodgkinson, R. Porritt, R. Mellors
With increasing geophysical applications using distributed acoustic sensing (DAS) technology, there is a need to implement a metadata standard specifically for DAS to facilitate the integration of DAS measurements across experiments and increase reusability. We propose a metadata standard intended primarily for the DAS research community, which fully describes the five key components of a DAS experiment: (1) interrogator; (2) data acquisition; (3) channels; (4) cable; and (5) fiber. The proposed metadata schema, which is the overall structure of the metadata, is hierarchical based, with a parent “overview” metadata block describing the experiment, and two main child branches describing the instrument (i.e., interrogator, photonics setup, and acquisition parameters) and the sensor locations (i.e., cable installation and fiber properties). The metadata schema is designed to be independent of the time-series data so that corrections and updates can be applied to the metadata without having to manipulate large volumes of time-series data. Unique identifiers are used as pointers that map different components within the metadata schema; they also provide a natural basis for the naming convention (i.e., source identifier) of the time-series data in which the time series can be described using identifiers defined by the metadata standard. We advocate for the metadata to be stored in a separate structure from the data itself. The metadata standard is successfully applied to four common scenarios: horizontal direct buried cable, dark fiber, borehole cable, and active survey, and two hypothetical scenarios: multiple interrogators to a single cable, and a single interrogator to multiple cables. Finally, we use GitHub to implement version control for the metadata standard, to enable community collaboration and facilitate sustainable development of the metadata standard, as the DAS technology and application continue to evolve.
随着使用分布式声学传感（DAS）技术的地球物理应用越来越多，有必要专门针对 DAS 实施元数据标准，以促进 DAS 测量在不同实验中的整合并提高可重用性。我们提出的元数据标准主要面向 DAS 研究界，全面描述了 DAS 实验的五个关键组成部分：(1) 询问器；(2) 数据采集；(3) 信道；(4) 电缆；(5) 光纤。拟议的元数据模式是元数据的整体结构，采用分层结构，其父 "概述 "元数据块描述实验，两个主要子分支分别描述仪器（即询问器、光子学设置和采集参数）和传感器位置（即电缆安装和光纤属性）。元数据模式的设计独立于时间序列数据，因此可以对元数据进行修正和更新，而无需处理大量的时间序列数据。独一无二的标识符可作为指针，映射元数据模式中的不同组件；它们还为时间序列数据的命名约定（即源标识符）提供了一个自然基础，其中的时间序列可使用元数据标准定义的标识符进行描述。我们主张将元数据与数据本身分开存储。元数据标准已成功应用于四种常见场景：水平直埋光缆、暗光纤、井眼光缆和主动勘测，以及两种假设场景：多个询问器连接单根光缆和单个询问器连接多根光缆。最后，随着 DAS 技术和应用的不断发展，我们使用 GitHub 对元数据标准实施版本控制，以实现社区协作，促进元数据标准的可持续发展。
{"title":"Toward a Metadata Standard for Distributed Acoustic Sensing (DAS) Data Collection","authors":"Voon Hui Lai, Kathleen M. Hodgkinson, R. Porritt, R. Mellors","doi":"10.1785/0220230325","DOIUrl":"https://doi.org/10.1785/0220230325","url":null,"abstract":"\u0000 With increasing geophysical applications using distributed acoustic sensing (DAS) technology, there is a need to implement a metadata standard specifically for DAS to facilitate the integration of DAS measurements across experiments and increase reusability. We propose a metadata standard intended primarily for the DAS research community, which fully describes the five key components of a DAS experiment: (1) interrogator; (2) data acquisition; (3) channels; (4) cable; and (5) fiber. The proposed metadata schema, which is the overall structure of the metadata, is hierarchical based, with a parent “overview” metadata block describing the experiment, and two main child branches describing the instrument (i.e., interrogator, photonics setup, and acquisition parameters) and the sensor locations (i.e., cable installation and fiber properties). The metadata schema is designed to be independent of the time-series data so that corrections and updates can be applied to the metadata without having to manipulate large volumes of time-series data. Unique identifiers are used as pointers that map different components within the metadata schema; they also provide a natural basis for the naming convention (i.e., source identifier) of the time-series data in which the time series can be described using identifiers defined by the metadata standard. We advocate for the metadata to be stored in a separate structure from the data itself. The metadata standard is successfully applied to four common scenarios: horizontal direct buried cable, dark fiber, borehole cable, and active survey, and two hypothetical scenarios: multiple interrogators to a single cable, and a single interrogator to multiple cables. Finally, we use GitHub to implement version control for the metadata standard, to enable community collaboration and facilitate sustainable development of the metadata standard, as the DAS technology and application continue to evolve.","PeriodicalId":21687,"journal":{"name":"Seismological Research Letters","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2024-02-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139809059","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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