It is time to submit nominations for the 2025 William B. Joyner Memorial Lecturer. Established by SSA in cooperation with the Earthquake Engineering Research Institute (EERI), these lectures honor Bill Joyner’s distinguished career at the U.S. Geological Survey and his abiding commitment to the exchange of information at the interface of earthquake science and earthquake engineering.Joyner Lecturers are chosen on the basis of their work at this interface, whether it involves contributions from earthquake science to earthquake engineering, or from earthquake engineering to earthquake science. Nominations can be made by any member of EERI or SSA, and the lecturer...
现在是提交 2025 年 William B. Joyner 纪念讲师提名的时候了。这些讲座由 SSA 与地震工程研究所 (EERI) 合作设立，旨在纪念 Bill Joyner 在美国地质调查局的杰出职业生涯，以及他对地震科学和地震工程界面信息交流的持久承诺。任何 EERI 或 SSA 成员均可提名，讲师...
{"title":"Nominations for the Next Joyner Lecturer Due 30 June","authors":"","doi":"10.1785/0220240178","DOIUrl":"https://doi.org/10.1785/0220240178","url":null,"abstract":"It is time to submit nominations for the 2025 William B. Joyner Memorial Lecturer. Established by SSA in cooperation with the Earthquake Engineering Research Institute (EERI), these lectures honor Bill Joyner’s distinguished career at the U.S. Geological Survey and his abiding commitment to the exchange of information at the interface of earthquake science and earthquake engineering.Joyner Lecturers are chosen on the basis of their work at this interface, whether it involves contributions from earthquake science to earthquake engineering, or from earthquake engineering to earthquake science. Nominations can be made by any member of EERI or SSA, and the lecturer...","PeriodicalId":21687,"journal":{"name":"Seismological Research Letters","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141513919","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}
Seismic signals, whether caused by earthquakes, other natural phenomena, or artificial noise sources, have specific characteristics in the time and frequency domains that contain crucial information reflecting their source. The analysis of seismic time series is an essential part of every seismology‐oriented study program. Enabling students to work with data collected from their own campus, including signals from both anthropogenic and natural seismic sources, can provide vivid, practical examples to make abstract concepts communicated in classes more concrete and relevant. Data from research‐grade broadband seismometers enable us to record time series of vibrations at a broad range of frequencies; however, these sensors are costly and are often deployed in remote places. Participation in the Raspberry Shake citizen science network enables seismology educators to record seismic signals on our own campuses and use these recordings in our classrooms and for public outreach. Yale University installed a Raspberry Shake three‐component, low‐cost seismometer in the Earth and Planetary Sciences department building in Summer 2022, enabling the detection of local, regional, and teleseismic earthquakes, microseismic noise, and anthropogenic noise sources from building construction, an explosive event in a steam tunnel, and general building use. Here, we discuss and illustrate the use of data from our Raspberry Shake in outreach and education activities at Yale. In particular, we highlight a series of ObsPy‐based exercises that will be used in courses taught in our department, including our upper‐level Introduction to Seismology course and our undergraduate classes on Natural Disasters and Forensic Geoscience.
{"title":"Follow the Trace: Becoming a Seismo‐Detective with a Campus‐Based Raspberry Shake Seismometer","authors":"Eric Löberich, Maureen D. Long","doi":"10.1785/0220230365","DOIUrl":"https://doi.org/10.1785/0220230365","url":null,"abstract":"Seismic signals, whether caused by earthquakes, other natural phenomena, or artificial noise sources, have specific characteristics in the time and frequency domains that contain crucial information reflecting their source. The analysis of seismic time series is an essential part of every seismology‐oriented study program. Enabling students to work with data collected from their own campus, including signals from both anthropogenic and natural seismic sources, can provide vivid, practical examples to make abstract concepts communicated in classes more concrete and relevant. Data from research‐grade broadband seismometers enable us to record time series of vibrations at a broad range of frequencies; however, these sensors are costly and are often deployed in remote places. Participation in the Raspberry Shake citizen science network enables seismology educators to record seismic signals on our own campuses and use these recordings in our classrooms and for public outreach. Yale University installed a Raspberry Shake three‐component, low‐cost seismometer in the Earth and Planetary Sciences department building in Summer 2022, enabling the detection of local, regional, and teleseismic earthquakes, microseismic noise, and anthropogenic noise sources from building construction, an explosive event in a steam tunnel, and general building use. Here, we discuss and illustrate the use of data from our Raspberry Shake in outreach and education activities at Yale. In particular, we highlight a series of ObsPy‐based exercises that will be used in courses taught in our department, including our upper‐level Introduction to Seismology course and our undergraduate classes on Natural Disasters and Forensic Geoscience.","PeriodicalId":21687,"journal":{"name":"Seismological Research Letters","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141513918","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}
We investigate the resolvability of a microseismic event location given a recording array composed of vertical distributed acoustic sensing (DAS) boreholes. We use a modified source‐scanning algorithm that takes into account both P and S waves. We transform the brightness maps it produces into probability density functions (PDFs), over which we carry out a resolution and uncertainty analysis. We apply this approach to microseismic events recorded by two vertical DAS boreholes as part of the Frontier Observatory for Research in Geothermal Energy (FORGE) project. We show that for the specific acquisition geometry in FORGE, the horizontal location of the events cannot be determined, but their depth can, similar to results obtained with a single borehole. Using synthetic examples, we show that the recording array’s geometry is the limiting factor in the determination of the horizontal location. We investigate various possible recording geometries composed of idealized DAS‐like vertical boreholes with varying locations and depths. We find that, besides the number of recordingd boreholes, their depth is the main factor influencing the location estimation uncertainty. The number and position of the boreholes mainly influence the spatial distribution of the PDF, whereas the boreholes’ depth mainly influences its size. Despite the simplicity of our analysis, it highlights the influence of the monitoring array design for microseismic events’ locating using vertical DAS arrays.
我们研究了由垂直分布式声学传感（DAS）钻孔组成的记录阵列对微地震事件位置的可分辨性。我们使用了一种改进的震源扫描算法，该算法同时考虑了 P 波和 S 波。我们将其生成的亮度图转换为概率密度函数 (PDF)，并对其进行分辨率和不确定性分析。我们将这种方法应用于地热能研究前沿观测站（FORGE）项目中由两个垂直 DAS 井眼记录的微地震事件。我们发现，对于 FORGE 项目中的特定采集几何形状，地震事件的水平位置无法确定，但其深度可以确定，这与单个钻孔获得的结果类似。通过合成实例，我们表明记录阵列的几何形状是确定水平位置的限制因素。我们研究了由不同位置和深度的理想化 DAS 型垂直钻孔组成的各种可能的记录几何结构。我们发现，除了记录钻孔的数量外，其深度也是影响位置估计不确定性的主要因素。钻孔的数量和位置主要影响 PDF 的空间分布，而钻孔深度则主要影响 PDF 的大小。尽管我们的分析很简单，但它强调了监测阵列设计对使用垂直 DAS 阵列进行微震事件定位的影响。
{"title":"Microseismic Event Location with Dual Vertical DAS Arrays: Insights from the FORGE 2022 Stimulation","authors":"Eyal Shimony, Ariel Lellouch","doi":"10.1785/0220230128","DOIUrl":"https://doi.org/10.1785/0220230128","url":null,"abstract":"We investigate the resolvability of a microseismic event location given a recording array composed of vertical distributed acoustic sensing (DAS) boreholes. We use a modified source‐scanning algorithm that takes into account both P and S waves. We transform the brightness maps it produces into probability density functions (PDFs), over which we carry out a resolution and uncertainty analysis. We apply this approach to microseismic events recorded by two vertical DAS boreholes as part of the Frontier Observatory for Research in Geothermal Energy (FORGE) project. We show that for the specific acquisition geometry in FORGE, the horizontal location of the events cannot be determined, but their depth can, similar to results obtained with a single borehole. Using synthetic examples, we show that the recording array’s geometry is the limiting factor in the determination of the horizontal location. We investigate various possible recording geometries composed of idealized DAS‐like vertical boreholes with varying locations and depths. We find that, besides the number of recordingd boreholes, their depth is the main factor influencing the location estimation uncertainty. The number and position of the boreholes mainly influence the spatial distribution of the PDF, whereas the boreholes’ depth mainly influences its size. Despite the simplicity of our analysis, it highlights the influence of the monitoring array design for microseismic events’ locating using vertical DAS arrays.","PeriodicalId":21687,"journal":{"name":"Seismological Research Letters","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141513987","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}
Jyun‐Yan Huang, Norman A. Abrahamson, Chih‐Hsuan Sung, Shu‐Hsien Chao
New global source‐scaling relations for the aspect ratio and rupture area for crustal earthquakes that include the width‐limited effect and a possible free‐surface effect are derived using a global dataset of finite‐fault rupture models. In contrast to the commonly used scaling relations between moment magnitude (M), fault length (L), width (W), and area, we built self‐consistent scaling relations by relating M to the aspect ratio (L/W) and to the fault area to model the change in the aspect ratio once the rupture width reaches the down‐dip width limit of the fault. The width‐limited effect of large‐magnitude earthquakes depends on the fault dip and a regional term for the seismogenic thickness. The magnitude scaling of the aspect ratio includes a break in the magnitude scaling that is dip angle dependent. This dip angle‐dependent magnitude scaling in the magnitude–area relation is modeled by a trilinear relation incorporating a dip‐related transition range. The effect of the free surface was observed using a normalized depth term and parameterizing the source by the depth of the top of the fault rupture; it is more apparent in the area scaling relation. The scaling differences are related to the fault geometry, not to the rake angle, as commonly assumed. Finally, the corresponding L and W scaling relations obtained by converting the area and aspect ratio models to L and W models not only show good agreement with the previous regional scaling laws on average but also provide better fault‐specific application due to the inclusion of a fault‐specific dip angle and seismogenic thickness.
利用有限断层破裂模型的全球数据集，得出了包括宽度限制效应和可能的自由表面效应在内的地壳地震长宽比和破裂面积的新的全球震源缩放关系。与常用的力矩震级（M）、断层长度（L）、宽度（W）和面积之间的比例关系不同，我们通过将 M 与高宽比（L/W）和断层面积联系起来，建立了自洽的比例关系，以模拟一旦破裂宽度达到断层下倾宽度极限时高宽比的变化。大震级地震的宽度限制效应取决于断层倾角和区域性成震厚度。纵横比的震级缩放包括与倾角有关的震级缩放断裂。震级-面积关系中这种与倾角相关的震级缩放关系是通过一个包含与倾角相关的过渡范围的三线关系来模拟的。使用归一化深度项和以断层破裂顶部深度为参数的震源，可以观察到自由表面的影响；这在面积缩放关系中更为明显。缩放差异与断层的几何形状有关，而不是像通常假设的那样与倾斜角有关。最后，通过将面积和长宽比模型转换为 L 和 W 模型而得到的相应 L 和 W 缩放关系不仅在平均水平上与之前的区域缩放规律显示出良好的一致性，而且由于包含了特定断层的倾角和震源厚度，还提供了更好的特定断层应用。
{"title":"New Empirical Source‐Scaling Laws for Crustal Earthquakes Incorporating Fault Dip and Seismogenic‐Thickness Effects","authors":"Jyun‐Yan Huang, Norman A. Abrahamson, Chih‐Hsuan Sung, Shu‐Hsien Chao","doi":"10.1785/0220240034","DOIUrl":"https://doi.org/10.1785/0220240034","url":null,"abstract":"New global source‐scaling relations for the aspect ratio and rupture area for crustal earthquakes that include the width‐limited effect and a possible free‐surface effect are derived using a global dataset of finite‐fault rupture models. In contrast to the commonly used scaling relations between moment magnitude (M), fault length (L), width (W), and area, we built self‐consistent scaling relations by relating M to the aspect ratio (L/W) and to the fault area to model the change in the aspect ratio once the rupture width reaches the down‐dip width limit of the fault. The width‐limited effect of large‐magnitude earthquakes depends on the fault dip and a regional term for the seismogenic thickness. The magnitude scaling of the aspect ratio includes a break in the magnitude scaling that is dip angle dependent. This dip angle‐dependent magnitude scaling in the magnitude–area relation is modeled by a trilinear relation incorporating a dip‐related transition range. The effect of the free surface was observed using a normalized depth term and parameterizing the source by the depth of the top of the fault rupture; it is more apparent in the area scaling relation. The scaling differences are related to the fault geometry, not to the rake angle, as commonly assumed. Finally, the corresponding L and W scaling relations obtained by converting the area and aspect ratio models to L and W models not only show good agreement with the previous regional scaling laws on average but also provide better fault‐specific application due to the inclusion of a fault‐specific dip angle and seismogenic thickness.","PeriodicalId":21687,"journal":{"name":"Seismological Research Letters","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141513988","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}
Ettore Biondi, Jorge C. Castellanos, Robert W. Clayton
The identification of preexisting near‐surface faults represents a piece of crucial information needed to correctly assess the seismic hazard of any area. The mapping of these structures is particularly challenging in densely populated and heavily urbanized areas. We use ambient seismic noise recorded by a dense array in Seal Beach, California, to image shallow fault lines via a reflected surface‐wave analysis. Our results highlight the presence of previously unknown shallow faults that correlate remarkably well with shallow seismicity and active survey images.
{"title":"Imaging Urban Hidden Faults with Ambient Noise Recorded by Dense Seismic Arrays","authors":"Ettore Biondi, Jorge C. Castellanos, Robert W. Clayton","doi":"10.1785/0220230408","DOIUrl":"https://doi.org/10.1785/0220230408","url":null,"abstract":"The identification of preexisting near‐surface faults represents a piece of crucial information needed to correctly assess the seismic hazard of any area. The mapping of these structures is particularly challenging in densely populated and heavily urbanized areas. We use ambient seismic noise recorded by a dense array in Seal Beach, California, to image shallow fault lines via a reflected surface‐wave analysis. Our results highlight the presence of previously unknown shallow faults that correlate remarkably well with shallow seismicity and active survey images.","PeriodicalId":21687,"journal":{"name":"Seismological Research Letters","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141513986","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}
R. Murdie, Huaiyu Yuan, John P. O’Donnell, Simon P. Johnson, Reza Ebrahimi, M. Rashidifard
In late 2022, the Geological Survey of Western Australia commenced the deployment of a new 10 yr seismic imaging array, Western Australia (WA) array. With the geological history of WA stretching from the Archean to the present, WA array is a natural platform for the study of lithospheric structures pre- and post-establishment of the modern plate tectonics. Despite being a stable craton, certain parts of WA have high seismic activity. This large-scale initiative will map areas of seismic risk for industrial infrastructure and future land use planning and investigate its relationship with the crustal and lithospheric mantle structures using a variety of methods. An economic objective is to identify prospective regions for mineral and energy exploration, especially in areas that have previously been underexplored or for new commodities such as hydrogen. The WA array imaging program will cover the whole State, more than 2.5 million square kilometers, using a grid station spacing of 40 km. The data acquisition is predicted to take 10 yr during which time 1600 stations will be deployed. It is anticipated that this will become one of the largest passive seismic investigations yet instigated. Here, we present and discuss the array design, current deployment status, initial modeling results, expected model updates, and potential implications for the program.
{"title":"WA Array: A High-Resolution Passive-Source Seismic Survey to Image the West Australian Lithosphere","authors":"R. Murdie, Huaiyu Yuan, John P. O’Donnell, Simon P. Johnson, Reza Ebrahimi, M. Rashidifard","doi":"10.1785/0220230415","DOIUrl":"https://doi.org/10.1785/0220230415","url":null,"abstract":"\u0000 In late 2022, the Geological Survey of Western Australia commenced the deployment of a new 10 yr seismic imaging array, Western Australia (WA) array. With the geological history of WA stretching from the Archean to the present, WA array is a natural platform for the study of lithospheric structures pre- and post-establishment of the modern plate tectonics. Despite being a stable craton, certain parts of WA have high seismic activity. This large-scale initiative will map areas of seismic risk for industrial infrastructure and future land use planning and investigate its relationship with the crustal and lithospheric mantle structures using a variety of methods. An economic objective is to identify prospective regions for mineral and energy exploration, especially in areas that have previously been underexplored or for new commodities such as hydrogen. The WA array imaging program will cover the whole State, more than 2.5 million square kilometers, using a grid station spacing of 40 km. The data acquisition is predicted to take 10 yr during which time 1600 stations will be deployed. It is anticipated that this will become one of the largest passive seismic investigations yet instigated. Here, we present and discuss the array design, current deployment status, initial modeling results, expected model updates, and potential implications for the program.","PeriodicalId":21687,"journal":{"name":"Seismological Research Letters","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2024-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141344662","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}
James D. Goltz, David J. Wald, Sara K. McBride, E.Harish Reddy, V. Quitoriano, J. Saunders
A magnitude 5.1 earthquake in California rarely generates more than momentary notice—a headline in local newspapers and a mention with footage on the evening news—then fades into obscurity for most people. But this earthquake, which occurred near the city of Ojai, is important for seismologists, social scientists, emergency managers, policymakers, and others who are engaged in implementing and improving earthquake early warning (EEW) technology and in assessing its value in public warnings. In this earthquake, ShakeAlert, the EEW system for the West Coast of the United States operated by the U.S. Geological Survey (USGS), was publicly activated and, for the first time, a substantial number of those who received alerts provided feedback on various aspects of the alerts they received. To capture data related to public attitudes and assessments regarding this and future alerts, a supplemental questionnaire was developed and associated with the “Did You Feel It?” (DYFI) earthquake reporting system, also operated by the USGS. The DYFI system received over 14,000 felt reports; 2490 of these were by people who received or expected to receive an alert before the onset of earthquake motion at their locations. This article analyzes the aggregate results of these EEW user reports, touching on the respondent’s situation upon receiving the alert, characteristics of the alert received, and, perhaps, most importantly, how the alert recipient responded if received before feeling earthquake motion. The new DYFI EEW supplemental questionnaire also inquired about respondent views of alert usefulness and preferences in future alerts. Our report provides a first glimpse of a range of behaviors, attitudes, and assessments by users of the recently implemented EEW system for the U.S. West Coast.
{"title":"The Ojai California Earthquake of 20 August 2023: Earthquake Early Warning Performance and Alert Recipient Response in the Mw 5.1 Event","authors":"James D. Goltz, David J. Wald, Sara K. McBride, E.Harish Reddy, V. Quitoriano, J. Saunders","doi":"10.1785/0220240023","DOIUrl":"https://doi.org/10.1785/0220240023","url":null,"abstract":"\u0000 A magnitude 5.1 earthquake in California rarely generates more than momentary notice—a headline in local newspapers and a mention with footage on the evening news—then fades into obscurity for most people. But this earthquake, which occurred near the city of Ojai, is important for seismologists, social scientists, emergency managers, policymakers, and others who are engaged in implementing and improving earthquake early warning (EEW) technology and in assessing its value in public warnings. In this earthquake, ShakeAlert, the EEW system for the West Coast of the United States operated by the U.S. Geological Survey (USGS), was publicly activated and, for the first time, a substantial number of those who received alerts provided feedback on various aspects of the alerts they received. To capture data related to public attitudes and assessments regarding this and future alerts, a supplemental questionnaire was developed and associated with the “Did You Feel It?” (DYFI) earthquake reporting system, also operated by the USGS. The DYFI system received over 14,000 felt reports; 2490 of these were by people who received or expected to receive an alert before the onset of earthquake motion at their locations. This article analyzes the aggregate results of these EEW user reports, touching on the respondent’s situation upon receiving the alert, characteristics of the alert received, and, perhaps, most importantly, how the alert recipient responded if received before feeling earthquake motion. The new DYFI EEW supplemental questionnaire also inquired about respondent views of alert usefulness and preferences in future alerts. Our report provides a first glimpse of a range of behaviors, attitudes, and assessments by users of the recently implemented EEW system for the U.S. West Coast.","PeriodicalId":21687,"journal":{"name":"Seismological Research Letters","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2024-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141340789","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}
J. A. Casas, G. Badi, T. D. Mikesell, Sebastián García, D. Draganov
Knowledge about the temporal evolution of a volcano is fundamental for an accurate understanding of the occurring physical dynamic processes and an appropriate assessment of the most probable near-future volcanic scenarios. Using seismic data recorded in the area of one of the most hazardous volcanoes along the Argentina–Chile, international border—Copahue volcano, we obtain information for an improved interpretation of the processes that occurred before, during, and after eruptive events. We use a single-station methodology to assess variations in the mechanical properties and internal structure of the Copahue volcano. Thus, we obtain information about structural alterations, friction and fractures, and variations in rigidity in the volcanic system. Our results show that the time variations of the evaluated seismic parameters correlate to the volcanic phenomena observed on the surface, that is, incandescence and ash emissions. Accounting for the physical processes, to which the analyzed seismic parameters are sensitive, and previous models developed for the area, we propose a physical model explaining the eruptive events that occurred at Copahue in the period 2018–2023. This model can potentially be used for the assessment of future scenarios, which is of fundamental importance for the institutions in charge of the real-time monitoring of Copahue volcano to improve the quality of their evidence-based decisions.
{"title":"Single-Station Multiparametric Seismic Monitoring of Copahue Volcano, Argentina–Chile (2018–2023)","authors":"J. A. Casas, G. Badi, T. D. Mikesell, Sebastián García, D. Draganov","doi":"10.1785/0220240074","DOIUrl":"https://doi.org/10.1785/0220240074","url":null,"abstract":"\u0000 Knowledge about the temporal evolution of a volcano is fundamental for an accurate understanding of the occurring physical dynamic processes and an appropriate assessment of the most probable near-future volcanic scenarios. Using seismic data recorded in the area of one of the most hazardous volcanoes along the Argentina–Chile, international border—Copahue volcano, we obtain information for an improved interpretation of the processes that occurred before, during, and after eruptive events. We use a single-station methodology to assess variations in the mechanical properties and internal structure of the Copahue volcano. Thus, we obtain information about structural alterations, friction and fractures, and variations in rigidity in the volcanic system. Our results show that the time variations of the evaluated seismic parameters correlate to the volcanic phenomena observed on the surface, that is, incandescence and ash emissions. Accounting for the physical processes, to which the analyzed seismic parameters are sensitive, and previous models developed for the area, we propose a physical model explaining the eruptive events that occurred at Copahue in the period 2018–2023. This model can potentially be used for the assessment of future scenarios, which is of fundamental importance for the institutions in charge of the real-time monitoring of Copahue volcano to improve the quality of their evidence-based decisions.","PeriodicalId":21687,"journal":{"name":"Seismological Research Letters","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2024-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141339989","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}
M. Köpfli, M. Denolle, W. Thelen, Peter Makus, Stephen D. Malone
An increase in seismic activity precedes most volcanic eruptions. Whereas event-based forecasting approaches have been successful, some eruptions remain unanticipated, resulting in casualties and damage. Our study leverages the recent advancements in ambient field seismology. We explore features extracted from continuous ambient fields using traditional methods, for example, peak ground velocity, peak ground acceleration, root mean square, root median square, real-time seismic amplitude measurement, and novel methods (displacement seismic amplitude ratio and spectral width). In addition, we explore unsupervised learning of higher order wavelet features using scattering networks. We find that combining all the methods was necessary to disentangle the effects of seismic sources from structural changes at Mount St. Helens. Although the ambient wavefield-based approach does not yield additional or more significant precursory signals than event-based methods at Mount St. Helens, our study demonstrates that the ambient wavefield provides supplementary information, mainly about structural changes and complements traditional methods. The ambient seismic wavefield offers additional insights into long-lasting processes. We find enhanced wave attenuation correlating with geochemical measurements. We interpret this as ongoing structural changes, such as dome growth or the evolution of the volcanic conduit system. On annual and decadal timescales, we interpret seasonal seismic attenuation in the shallow subsurface as groundwater fluctuations, corroborated by observations at the nearby Spirit Lake level. This multimethod approach at Mount St. Helens sheds light on a volcanic system’s underlying dynamics and structure.
{"title":"Examining 22 Years of Ambient Seismic Wavefield at Mount St. Helens","authors":"M. Köpfli, M. Denolle, W. Thelen, Peter Makus, Stephen D. Malone","doi":"10.1785/0220240079","DOIUrl":"https://doi.org/10.1785/0220240079","url":null,"abstract":"\u0000 An increase in seismic activity precedes most volcanic eruptions. Whereas event-based forecasting approaches have been successful, some eruptions remain unanticipated, resulting in casualties and damage. Our study leverages the recent advancements in ambient field seismology. We explore features extracted from continuous ambient fields using traditional methods, for example, peak ground velocity, peak ground acceleration, root mean square, root median square, real-time seismic amplitude measurement, and novel methods (displacement seismic amplitude ratio and spectral width). In addition, we explore unsupervised learning of higher order wavelet features using scattering networks. We find that combining all the methods was necessary to disentangle the effects of seismic sources from structural changes at Mount St. Helens. Although the ambient wavefield-based approach does not yield additional or more significant precursory signals than event-based methods at Mount St. Helens, our study demonstrates that the ambient wavefield provides supplementary information, mainly about structural changes and complements traditional methods. The ambient seismic wavefield offers additional insights into long-lasting processes. We find enhanced wave attenuation correlating with geochemical measurements. We interpret this as ongoing structural changes, such as dome growth or the evolution of the volcanic conduit system. On annual and decadal timescales, we interpret seasonal seismic attenuation in the shallow subsurface as groundwater fluctuations, corroborated by observations at the nearby Spirit Lake level. This multimethod approach at Mount St. Helens sheds light on a volcanic system’s underlying dynamics and structure.","PeriodicalId":21687,"journal":{"name":"Seismological Research Letters","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2024-06-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141352031","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}
As the largest instrumentally recorded earthquake in the fold-and-thrust belt of the northwestern Zagros mountain so far, the fault structure of the 2017 Mw 7.3 Sarpol-e Zahab earthquake and its contribution to regional crustal shortening remain controversial. Here, we utilize the integration of Interferometric Synthetic Aperture Radar observations and 2D finite element models incorporating various fault geometries such as planar faults, ramp-flat faults, and the combined models of ramp-flat and splay faults to explore frictional afterslip process due to coseismic stress changes following the mainshock. Our findings suggest that a ramp-flat frictional afterslip model, characterized by the maximum afterslip of ∼1.0 m and frictional variations (Δμ) of ∼0.001 and ∼0.0002 for the up-dip and down-dip portions, respectively, better explains the long-wavelength postseismic deformation than planar fault models. However, an integration model of a ramp-flat and a splay fault further improves the model fit, although the splay fault’s frictional slip is limited to <0.2 m, which is much smaller than that on the ramp-flat part (∼0.9 m). Considering the relocated aftershocks and structural cross-sections, the combined model could be best attributed to fault slip on the blind Mountain Front fault. Our findings thus suggest the complexity of the fault interactions between the basement and sedimentary cover in the Zagros, and that this largest basement-involved event in the region contributes to both thick- and thin-skinned shortening via seismic and aseismic behaviors, respectively.
{"title":"Ramp-Flat and Splay Faulting Illuminated by Frictional Afterslip Following the 2017 Mw 7.3 Sarpol-e Zahab Earthquake","authors":"Zelong Guo, M. Baes, M. Motagh","doi":"10.1785/0220230425","DOIUrl":"https://doi.org/10.1785/0220230425","url":null,"abstract":"\u0000 As the largest instrumentally recorded earthquake in the fold-and-thrust belt of the northwestern Zagros mountain so far, the fault structure of the 2017 Mw 7.3 Sarpol-e Zahab earthquake and its contribution to regional crustal shortening remain controversial. Here, we utilize the integration of Interferometric Synthetic Aperture Radar observations and 2D finite element models incorporating various fault geometries such as planar faults, ramp-flat faults, and the combined models of ramp-flat and splay faults to explore frictional afterslip process due to coseismic stress changes following the mainshock. Our findings suggest that a ramp-flat frictional afterslip model, characterized by the maximum afterslip of ∼1.0 m and frictional variations (Δμ) of ∼0.001 and ∼0.0002 for the up-dip and down-dip portions, respectively, better explains the long-wavelength postseismic deformation than planar fault models. However, an integration model of a ramp-flat and a splay fault further improves the model fit, although the splay fault’s frictional slip is limited to <0.2 m, which is much smaller than that on the ramp-flat part (∼0.9 m). Considering the relocated aftershocks and structural cross-sections, the combined model could be best attributed to fault slip on the blind Mountain Front fault. Our findings thus suggest the complexity of the fault interactions between the basement and sedimentary cover in the Zagros, and that this largest basement-involved event in the region contributes to both thick- and thin-skinned shortening via seismic and aseismic behaviors, respectively.","PeriodicalId":21687,"journal":{"name":"Seismological Research Letters","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2024-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141365502","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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