Seismological Research Letters最新文献_第4页

Improved Earthquake Clustering Using a Density-Adaptive DBSCAN Algorithm: An Example from Iran 使用密度自适应 DBSCAN 算法改进地震聚类：伊朗实例

IF 3.3 3区地球科学

Seismological Research Letters Pub Date : 2023-12-06 DOI: 10.1785/0220220305

Sina Sabermahani, Andrew W. Frederiksen

{"title":"Improved Earthquake Clustering Using a Density-Adaptive DBSCAN Algorithm: An Example from Iran","authors":"Sina Sabermahani, Andrew W. Frederiksen","doi":"10.1785/0220220305","DOIUrl":"https://doi.org/10.1785/0220220305","url":null,"abstract":"\u0000 DBSCAN is a widely used unsupervised machine learning algorithm for clustering and spatial data analysis. However, the accuracy of the algorithm is highly dependent on the selection of its hyperparameters, minimum samples (Smin), the minimum number of points required to form a cluster, and ϵ, the maximum distance between points. In this study, we propose a modification to the DBSCAN algorithm by introducing an event density map replacing Smin and ε. Through this method, we decrease the number of hyperparameters from two to one, N which represents the number of cells in the event density map, simplifying, and speeding up optimization. As a result, the optimization of the algorithm will be improved as the sole factor to consider is the size of each cell. In addition, the utilization of dynamic Smin will provide more effective clustering because it is better suited to regions that have a variable earthquake density. We used the Iranian earthquake catalog for testing the algorithm, and we compared the outcomes to the Mirzaei et al. (1998) model as a standard for evaluation. Because this algorithm allows for density contrasts between clusters, it can be a good indicator when studying the zonation of a new area. The findings were more consistent than those of other methods and may offer additional insight into the seismotectonic of Iran. Other than earthquake studies, this algorithm can be applied in multiple fields of science and engineering for clustering datasets with variable-density clusters.","PeriodicalId":21687,"journal":{"name":"Seismological Research Letters","volume":"12 6","pages":""},"PeriodicalIF":3.3,"publicationDate":"2023-12-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138595697","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}

引用次数: 0

Erratum to An Evaluation of the Timing Accuracy of Global and Regional Seismic Stations and Networks 对全球和区域地震台和网络定时精度的评估》的勘误

IF 3.3 3区地球科学

Seismological Research Letters Pub Date : 2023-12-06 DOI: 10.1785/0220230360

Yi Yang, Xiaodong Song, A. Ringler

引用次数: 0

GEOSCOPE Network: 40 Yr of Global Broadband Seismic Data GEOSCOPE 网络：40 年全球宽带地震数据

IF 3.3 3区地球科学

Seismological Research Letters Pub Date : 2023-12-04 DOI: 10.1785/0220230176

Nicolas Leroy, Martin Vallée, D. Zigone, Barbara Romanowicz, É. Stutzmann, Alessia Maggi, C. Pardo, J. Montagner, M. Bès de Berc, C. Broucke, S. Bonaimé, Geneviève Roult, J. Thore, Armelle Bernard, Michel Le Cocq, O. Sirol, Luis Rivera, J. Lévêque, Michel Cara, Frédérick Pesqueira

{"title":"GEOSCOPE Network: 40 Yr of Global Broadband Seismic Data","authors":"Nicolas Leroy, Martin Vallée, D. Zigone, Barbara Romanowicz, É. Stutzmann, Alessia Maggi, C. Pardo, J. Montagner, M. Bès de Berc, C. Broucke, S. Bonaimé, Geneviève Roult, J. Thore, Armelle Bernard, Michel Le Cocq, O. Sirol, Luis Rivera, J. Lévêque, Michel Cara, Frédérick Pesqueira","doi":"10.1785/0220230176","DOIUrl":"https://doi.org/10.1785/0220230176","url":null,"abstract":"\u0000 The GEOSCOPE observatory (Institut de physique du globe de Paris [IPGP] and École et Observatoire des Sciences de la Terre de Strasbourg, 1982) provides more than four decades of high-quality continuous broadband data to the scientific community. Started in 1982 with only two stations, the network has grown over the years thanks to numerous international partnerships. At present, 34 stations operate in 18 countries across all continents and on islands throughout the oceans, filling important gaps in global Earth coverage. Most of the first installed stations are still running today, allowing for long-term observations, and new sites are being prospected to further improve global coverage. Over the years, GEOSCOPE has contributed to defining today’s global seismology standards (data format, data quality level, instrumentation requirements), being the French contribution to the international effort for global seismic observations. The stations are instrumented with the best quality seismometers (from the very first STS-1 in the early 80s to the last STS-6A and Trillium T360 today) and digitizers (Q330HR and Centaur) to record with high fidelity the ground motions generated by all types of seismic sources. Real-time data are sent to the tsunami warning centers and both validated and real-time data are available at the IPGP, Epos-France and Earthscope data centers. The quality of GEOSCOPE data and metadata is ensured by daily and yearly validation that enables issue detection and mitigation. GEOSCOPE, in collaboration with the other global networks, has played and continues to play a crucial role in the study of Earth’s structure and global dynamics and the characterization of all types of seismic sources.","PeriodicalId":21687,"journal":{"name":"Seismological Research Letters","volume":"61 18","pages":""},"PeriodicalIF":3.3,"publicationDate":"2023-12-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138605099","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}

引用次数: 0

Seismotectonics of the Querétaro Region (Central Mexico) and the 1934 MI 4.8 Earthquake North of Celaya 克雷塔罗地区（墨西哥中部）的地震构造和 1934 年塞拉亚北部 MI 4.8 地震

IF 3.3 3区地球科学

Seismological Research Letters Pub Date : 2023-12-04 DOI: 10.1785/0220230256

Max Suter, Lucero Morelos-Rodríguez

{"title":"Seismotectonics of the Querétaro Region (Central Mexico) and the 1934 MI 4.8 Earthquake North of Celaya","authors":"Max Suter, Lucero Morelos-Rodríguez","doi":"10.1785/0220230256","DOIUrl":"https://doi.org/10.1785/0220230256","url":null,"abstract":"\u0000 The Querétaro region (central Mexico) is located in the trans-Mexican volcanic belt, an active volcanic arc related to the subduction of oceanic plates along the Pacific margin of Mexico. It is characterized by north–south-striking normal faults of the southern Basin and Range Province, up to 40 km long and with morphologically pronounced scarps, such as the San Miguel de Allende fault and the faults forming the Querétaro graben. These faults are located directly north of a major regional-scale system of east–west striking, seismically active intra-arc normal faults that are oriented parallel to the axis of the volcanic arc. Where the two orthogonal normal fault systems interfere, the outcrop-scale observations show that the east–west intra-arc fault system overprints the Basin and Range Province structures. Here we document a 1934 earthquake in a region previously not known for seismic activity. Our study is mostly based on an unpublished contemporary dossier preserved at Archivo Histórico del Instituto de Geología de la Universidad Nacional Autónoma de México, a recently inventoried archive that also preserves several unpublished macroseismic and instrumental studies of major Mexican subduction zone earthquakes between 1911 and 1954. A mainshock–aftershock sequence that initiated 14 July 1934 is documented by instrumental recordings at the Tacubaya observatory and by macroseismic observations at ten population centers, ranging in intensity between five and seven on the modified Mercalli scale. Based on the size of the damage area, the intensity magnitude of the mainshock is estimated at 4.8 ± 0.5. Based on the intensity distribution, the epicenter was located in the Laja River valley north-northeast of the town of Celaya, in the south-southwestern extrapolated continuation of the San Miguel de Allende normal fault scarp, which suggests that this fault extends to the epicentral region of the 1934 earthquake and is characterized by recurrent Quaternary tectonic activity.","PeriodicalId":21687,"journal":{"name":"Seismological Research Letters","volume":"39 12","pages":""},"PeriodicalIF":3.3,"publicationDate":"2023-12-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138602537","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}

引用次数: 0

Nearly Simultaneous Pairs and Triplets of Historical Destructive Earthquakes with Distant Epicenters in the Italian Apennines 意大利亚平宁山脉几乎同时发生的几对和三对震源较远的历史性破坏性地震

IF 3.3 3区地球科学

Seismological Research Letters Pub Date : 2023-12-04 DOI: 10.1785/0220230135

Paolo Galli

引用次数: 0

BPMF: A Backprojection and Matched-Filtering Workflow for Automated Earthquake Detection and Location BPMF：用于地震自动探测和定位的反向投影和匹配过滤工作流程

IF 3.3 3区地球科学

Seismological Research Letters Pub Date : 2023-12-04 DOI: 10.1785/0220230230

É. Beaucé, W. Frank, L. Seydoux, Piero Poli, Nathan Groebner, R. D. van der Hilst, Michel Campillo

{"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}

引用次数: 0

Estimation of Site Effects and Equivalent Source Parameters of Wenchuan Earthquake Based on Generalized Chaotic Particle Inversion Technique 基于广义混沌粒子反演技术的汶川地震场地效应和等效震源参数估计

IF 3.3 3区地球科学

Seismological Research Letters Pub Date : 2023-11-30 DOI: 10.1785/0220230028

Ke-Lin Chen, Xue-Liang Chen, Jingyan Lan, Li-Jun Qiu, Yi-Ling Zhu

{"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}

引用次数: 0

Estimation of Uncertainty in the Average Rate of Earthquakes Exceeding a Magnitude Threshold 超过震级阈值的地震平均发生率的不确定性估算

IF 3.3 3区地球科学

Seismological Research Letters Pub Date : 2023-11-30 DOI: 10.1785/0220230242

Sepideh J. Rastin, D. Rhoades, Chris Rollins, Matthew C. Gerstenberger

{"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}

引用次数: 0

Global Seismic Networks Operated by the U.S. Geological Survey 美国地质调查局运营的全球地震网络

IF 3.3 3区地球科学

Seismological Research Letters Pub Date : 2023-11-29 DOI: 10.1785/0220230178

D. Wilson, C. R. Hutt, L. Gee, A. Ringler, R. Anthony

{"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}

引用次数: 0

Coseismic Deformation of the 2023 Türkiye Earthquake Doublet from Sentinel-1 InSAR and Implications for Earthquake Hazard 哨兵-1 InSAR 提供的 2023 年图尔基耶双地震的地震形变及其对地震灾害的影响

IF 3.3 3区地球科学

Seismological Research Letters Pub Date : 2023-11-29 DOI: 10.1785/0220230282

Xiaopeng Tong, Yongzhe Wang, Shi Chen

{"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}

引用次数: 0