Journal of Seismology最新文献

{"title":"Characterization of seismic b-value around kopili fault and its neighboring region prior to 28th April 2021 earthquake","authors":"Vickey Sharma,&nbsp;Dipok Kumar Bora,&nbsp;Devajit Hazarika,&nbsp;Rajib Biswas","doi":"10.1007/s10950-024-10232-5","DOIUrl":"10.1007/s10950-024-10232-5","url":null,"abstract":"<div><p>In the present study, the spatio-temporal variation of the seismic b-value in the vicinity of the Kopili fault and its surrounding area has been analysed using the unified and homogenous earthquake catalog of historical and instrumental (1950–2021) earthquake events. The study region is subdivided into 16 equisized square grids of 1° × 1° dimension, and the b-value is computed for each grid using the maximum likelihood method. The spatial distribution of the b-value varies from 0.58 to 1.14. The Kolmogorov–Smirnov (K-S) test has been conducted to check the significance of the spatial-temporal and depth-wise distributions of the b-value. The epicentral location of April 28th, 2021, lies in the low-b-value square grid. Likewise, the temporal b-value curve shows a decreasing trend before the occurrence of the April 28th, 2021 earthquake. The mean return period of the April 28th, 2021earthquake and the most probable maximum annual magnitude earthquake are also computed for this region. Meanwhile, the spatial associations and anomalous patterns between the b-value and factors like seismic moment or energy release and focal depth are assessed, as they contribute to a more comprehensive understanding of the seismicity in this area. The antithetical relationship between the b-value and seismic moment or energy release is established. While variation in b-value with depth provides new insights, low b-values are linked to the top of the crust, which could mean that the crust is uniform and that a lot of stress is building up.</p></div>","PeriodicalId":16994,"journal":{"name":"Journal of Seismology","volume":"28 4","pages":"1001 - 1025"},"PeriodicalIF":1.6,"publicationDate":"2024-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141746105","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Revisiting Stepp’s method for the completeness of regional seismic catalogues","authors":"Narsiram Gurjar,&nbsp;Dhiman Basu","doi":"10.1007/s10950-024-10231-6","DOIUrl":"10.1007/s10950-024-10231-6","url":null,"abstract":"<div><p>An important step in seismic hazard analysis is investigating the completeness of available data. Out of the various methods proposed by several researchers, Stepp’s method is one of the most commonly used methods for completeness analysis. Some drawbacks are identified in this method, which results in erroneous estimation of the completeness period. This paper suggests another way of estimation based on the 2-point moving average of the mean annual rate of occurrence of events. The new procedure is able to overcome the problems identified in Stepp’s method and is validated using five catalogues from different regions. The analysis result includes the completeness period determination for different catalogues before and after correction, together with Magnitude-Frequency recurrence relation coefficients compared with Stepp’s method.</p></div>","PeriodicalId":16994,"journal":{"name":"Journal of Seismology","volume":"28 4","pages":"1055 - 1086"},"PeriodicalIF":1.6,"publicationDate":"2024-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141746106","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Comparison between rupture parameters of intermediate and deep earthquakes at the Peru–Brazil–Bolivia border and northern Chile","authors":"Carmen Pro,&nbsp;Hernando Tavera,&nbsp;Maurizio Mattesini,&nbsp;Lucía Escudero,&nbsp;Elisa Buforn,&nbsp;Agustín Udías,&nbsp;Estela Centeno","doi":"10.1007/s10950-024-10229-0","DOIUrl":"10.1007/s10950-024-10229-0","url":null,"abstract":"<div><p>We determined the main parameters of the source rupture process of intermediate- and deep-depth earthquakes occurring in the Peru–Brazil–Bolivia border region and northern Chile. The parameters of depth, fault-plane orientation, scalar seismic moment, slip distribution, and radiated seismic energy are obtained from seismograms. We selected 15 intermediate-depth earthquakes (100 km &lt; h &lt; 300 km) and 10 very deep earthquakes (h &gt; 500 km) with magnitudes M_W ≥ 6.0. For most events, the slip distribution over the rupture plane shows a single asperity, and the source time function presents a simple pulse. There are differences between intermediate-depth and deep earthquakes. The rupture areas, maximum slip and source time function (STF) duration are larger for intermediate-depth events than for deep events. Additionally, the STF’s show a sharper increase for deep earthquakes. The scaled radiated seismic energy shows larger values for deep depth events. The stress regime pattern derived from the obtained focal mechanism agrees with the geometry of the subduction of the Nazca plate. At intermediate depths, in the northern area up to 12°S, the stress pattern corresponds to a horizontal extension, while in the southern area, the tension axes dip at an angle of 30°. At deep depths, the stress regime corresponds to vertical compression in the north and dips of approximately 45° in the south.</p></div>","PeriodicalId":16994,"journal":{"name":"Journal of Seismology","volume":"28 4","pages":"973 - 999"},"PeriodicalIF":1.6,"publicationDate":"2024-07-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10950-024-10229-0.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141570109","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Spatiotemporal properties of the 2020 – 2021 Petrinja (Croatia) earthquake sequence","authors":"Eirini Sardeli,&nbsp;Georgios Michas,&nbsp;Kyriaki Pavlou,&nbsp;Davide Zaccagnino,&nbsp;Filippos Vallianatos","doi":"10.1007/s10950-024-10228-1","DOIUrl":"10.1007/s10950-024-10228-1","url":null,"abstract":"<div><p>The Petrinja earthquake sequence started on December 28, 2020, with a destructive <i>M</i>_<i>L</i> 6.2 mainshock occurring in the area, preceded by a <i>M</i>_<i>L</i> 5.08 foreshock, following a long period of relative seismic quiescence. Over the first six months of the Petrinja earthquake sequence, almost 14,000 events were recorded. In the present work, we separated seismic events based on their spatial concentration using a density-based clustering algorithm, DBSCAN. We identified four main clusters and analyzed their spatiotemporal properties using the notions of Non-Extensive Statistical Physics (NESP). This framework, which relies on Tsallis entropy (<i>S</i>_<i>q</i>), describes the scaling behavior of complex systems. In this frame, we investigated the inter-event time (<i>T</i>) and distance (<i>D</i>) distributions, providing the <i>q</i>_<i>T</i> and <i>q</i>_<i>D</i> entropic parameters, respectively. Additionally, we studied the frequency–magnitude distributions in terms of the fragment–asperity model, leading to the determination of the non-extensive parameter <i>q</i>_<i>M</i>. The results of the analysis suggest that the statistical properties of the Petrinja earthquake sequence can be effectively reproduced utilizing NESP. Furthermore, the coseismic static Coulomb stress changes were estimated, indicating that the clusters’ seismic events may have resulted from a complex fault system's (re)activation. In addition, the effective static stress drop was estimated for each spatial cluster. Lastly, the temporal patterns of the earthquake evolution are discussed using the superstatistics approach, indicating that the temporal progression of the Petrinja earthquake clusters is governed by a very low number of degrees of freedom, highlighting the spatiotemporal organization of each cluster.</p></div>","PeriodicalId":16994,"journal":{"name":"Journal of Seismology","volume":"28 4","pages":"899 - 920"},"PeriodicalIF":1.6,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141507400","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Reevaluating soil amplification using multi-spectral HVSR technique in La Chana Neighborhood, Granada, Spain","authors":"Carlos Jose Araque-Perez","doi":"10.1007/s10950-024-10227-2","DOIUrl":"10.1007/s10950-024-10227-2","url":null,"abstract":"<div><p>This work presents a thorough reevaluation of soil amplification in the La Chana neighborhood of Granada through a pioneering application of the horizontal-to-vertical spectral ratio technique on seismic noise data using various spectral approaches. The research recycles old seismic noise data recorded at 34 stations with 2 Hz instruments in the year 2010, supplemented with additional measurements recorded with broadband seismometers at nearby locations in the years 2013 and 2017. Initial traditional processing identifies a narrowband dominant frequency around 1.5 Hz, attributed to artificial or anthropogenic sources. To address this, the Maximum Entropy Algorithm was implemented to smooth the spectral response below 1 Hz, and filter out frequency peaks with very narrow spectral bands, while preserving the narrowband frequency around 1.5 Hz in some records. The Thomson Multitaper method further refined the spectral ratio, emphasizing the detection and suppression of narrow frequency bands that may be related to industrial activity. The results demonstrated the reappearance of the 1.5 Hz frequency, but this time without narrow bandwidths, indicating its possible correlation with the natural ground movement. Fundamental periods, ranging from 0.45 s to 0.88 s, suggest a diverse lithological composition, indicating the presence of layers of sands, clays, conglomerates, and carbonates over a basement that represents the main impedance contrast in the area. The multispectral approach surpasses conventional methods in precision and reliability, providing valuable insights for earthquake risk assessment, urban planning, and engineering decisions in seismically active regions.</p></div>","PeriodicalId":16994,"journal":{"name":"Journal of Seismology","volume":"28 4","pages":"921 - 949"},"PeriodicalIF":1.6,"publicationDate":"2024-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10950-024-10227-2.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141507401","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Directivity analysis and source parameter estimation: insights from the 2014 Arzew earthquake, Mw3.9, northwestern Algeria","authors":"Oualid Boulahia,&nbsp;Fethi Semmane","doi":"10.1007/s10950-024-10226-3","DOIUrl":"10.1007/s10950-024-10226-3","url":null,"abstract":"<div><p>The March 20, 2014, magnitude M_w3.9 earthquake near Arzew, Algeria, instigated a study to deepen comprehension of seismic activity and hazard in the region. Analyzing data from Algerian and Spanish seismic networks, we explored earthquake characteristics and rupture mechanisms. The earthquake's epicenter was located at 35.825° latitude and -0.366° longitude, with a depth of 7 km, exhibiting intensity IV-V in the Arzew-Oran area. Preceding this event, a magnitude M_D3.1 foreshock occurred on February 1, 2014, at the same location. The waveforms of the foreshock and mainshock exhibited striking similarities, validating the effectiveness of the Empirical Green's Function method employed for deconvolution. Through waveform inversion and P-wave polarities, we estimated the focal mechanism, revealing a near-pure strike-slip mechanism with nodal planes oriented ~E-W and ~N-S. The rupture process, characterized by multiple episodes, propagated predominantly from the south towards the N5°-15°E direction at a velocity around 2.7 km/s along an 870 m fault length in 0.32 seconds. The mainshock's fault plane was identified as the N-S plane, indicating the direction of rupture propagation. Source parameter estimation utilizing the EGF method revealed larger corner frequencies and stress drops compared to individual spectra estimation, attributed to the method’s improved correction for attenuation and site effects, without the need for simplified a priori models. Despite its low magnitude, the 2014 Arzew earthquake provided valuable insights into the region’s seismic behavior, contributing significantly to ground motion predictions. In particular, the study highlights the necessity of accounting for rupture directivity in seismic hazard assessments and mitigation strategies.</p></div>","PeriodicalId":16994,"journal":{"name":"Journal of Seismology","volume":"28 4","pages":"951 - 972"},"PeriodicalIF":1.6,"publicationDate":"2024-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141507402","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Earthquake detection capacity of the Dense Oceanfloor Network system for Earthquakes and Tsunamis (DONET)","authors":"K. Z. Nanjo,&nbsp;Y. Yamamoto,&nbsp;K. Ariyoshi,&nbsp;H. Horikawa,&nbsp;S. Yada,&nbsp;N. Takahashi","doi":"10.1007/s10950-024-10219-2","DOIUrl":"10.1007/s10950-024-10219-2","url":null,"abstract":"<div><p>We studied the earthquake detection capacity of DONET (Dense Oceanfloor Network system for Earthquakes and Tsunamis) operating in the Nankai Trough, a target region monitored for future megathrust earthquakes. The focus of this paper was to evaluate the impact on this capacity from the malfunction of parts of the network. For this purpose, the completeness magnitude, above which all earthquakes are considered to be detected by a seismic network, was used. Then, a catalog that includes events observed by DONET was used. We found spatiotemporal variability of completeness magnitude, ranging from values below 1 in one of the areas where stations are densely deployed to values above 2 at the periphery and outside of the DONET area. We conducted a simulation computation for cases of malfunction of densely distributed stations. The results showed that completeness estimates in the area near the malfunctioning stations were about 1 magnitude larger. This implies that malfunction repair and/or replacement with new stations would be desirable because they pronouncedly affect earthquake monitoring. We then demonstrated an example of how to use the information of completeness magnitude as prior knowledge to compute the <i>b</i> value of the Gutenberg-Richter distribution. The result indicates the <i>b</i> value as a proxy that can help to image stress heterogeneity when there is a magnitude-6 class slow slip event on the Nankai Trough plate boundary.</p></div>","PeriodicalId":16994,"journal":{"name":"Journal of Seismology","volume":"28 3","pages":"787 - 810"},"PeriodicalIF":1.6,"publicationDate":"2024-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10950-024-10219-2.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141552551","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Significance of VP/VS ratio in locating earthquakes of a long-duration swarm in the western coast of India","authors":"Himangshu Paul,&nbsp;T. C. Sunilkumar,&nbsp;Vineet K. Gahalaut,&nbsp;D. Srinagesh,&nbsp;M. Shekar","doi":"10.1007/s10950-024-10223-6","DOIUrl":"10.1007/s10950-024-10223-6","url":null,"abstract":"<div><p>The earthquake swarm in Palghar, western India, is a natural laboratory to understand long-duration seismogenesis. However, it requires an accurate estimation of the key parameters, such as earthquake locations and the velocity model of the region. Two separate studies performed by two organisations in India, the CSIR-National Geophysical Research Institute (NGRI) and the National Center for Seismology (NCS) reported significantly differing results from the first 8–12 months of earthquake monitoring in Palghar. CSIR-NGRI reported the depth of earthquakes in the range of 4–15 km, whereas NCS reported a much shallower depth down to 7 km only. We investigate the reason for this depth discrepancy by analysing datasets from the networks of both these organisations. We find that no available velocity models are able to reconcile the depth difference between the two datasets. Selection criteria generally adopted to determine a good velocity model, such as travel-time residuals and location errors, also failed to identify a suitable velocity model. Several synthetic tests helped us to identify that the network geometry and source-station separation are contributing factors to the observed depth difference. However, the main reason for the discrepancy was found to be inconsistent velocity models used for location at both networks. The main objective of our work is to estimate a velocity model which minimises the depth discrepancy between both datasets. In this regard, we synthetically generated hundreds of models with different V_P and V_P/V_S ratios, followed by a grid search of V_P and V_P/V_S ratios, which harmonises the location from the two datasets. The best model consists of a V_P lying between 5.55–5.85 km/s and a V_P/V_S ratio between 1.77–1.81. For this velocity model, there is a greater overlap of the hypocentral clouds from both networks, and about 80% of the earthquakes of the CSIR-NGRI network were located within depths ≤ 7 km. We find that location errors vary seasonally, which is also related to the V_P/V_S of the crust. Since earlier studies have also found a strong correspondence between rainfall and seismicity in this region, we infer that the high V_P/V_S ratio might have been caused by the rainfall saturation of cracks in the Palghar seismicity zone.</p></div>","PeriodicalId":16994,"journal":{"name":"Journal of Seismology","volume":"28 3","pages":"859 - 877"},"PeriodicalIF":1.6,"publicationDate":"2024-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141254304","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Investigation of the discrepancy in the earthquake magnitude values reported by different agencies in the Western Canada Sedimentary basin","authors":"Alireza Babaie Mahani,&nbsp;Honn Kao,&nbsp;Brindley Smith","doi":"10.1007/s10950-024-10225-4","DOIUrl":"10.1007/s10950-024-10225-4","url":null,"abstract":"<div><p>Earthquake magnitude plays a crucial role in assessing ground shaking severity and formulating mitigation strategies for both natural and induced earthquakes. This study specifically focuses on the Western Canada Sedimentary Basin (WCSB) and examines the estimation of local magnitude (<span>({M}_{L})</span>) by different agencies. The analysis includes the application of various distance calibration functions for the Richter’s methodology, incorporating both Richter's original function (Richter, Elementary Seismology, Freeman, San Francisco, Calif, 1958) and WCSB-specific calibration functions proposed by Yenier 2017 Bull Seismol Soc Am 107:1421-1431 and Babaie Mahani and Kao 2019 Seismol Res Lett 90:203-211, 2020 CSEG Recorder 45:12.</p><p>In the WCSB, fluid injection has caused significant increase in the rate of seismicity in several localities, prompting the regulatory agencies to request suspension of injection operations after the occurrence of red-light (i.e., <span>({M}_{L})</span> ≥ 4) events. Our investigation, based on a new dataset, sheds light on the significant effects due to distance calibration functions on the <span>({M}_{L})</span> estimation. Notably, we observe that using the original Richter’s calibration function designed for southern California results in more than three times the number of red-light events compared to employing more appropriate calibration functions. Our results point to the unnecessary economic consequences when exaggerated <span>({M}_{L})</span> values are used in the regulatory process and underscores the need for adopting proper calibration functions for seismic monitoring in the WCSB.</p></div>","PeriodicalId":16994,"journal":{"name":"Journal of Seismology","volume":"28 3","pages":"753 - 764"},"PeriodicalIF":1.6,"publicationDate":"2024-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141254669","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Cumulative Absolute Velocity (CAV) parameter estimation in earthquake emergency response based on a support vector machine","authors":"Heyi Liu,&nbsp;Wentao Sun,&nbsp;Shanyou Li,&nbsp;Xueying Zhou,&nbsp;Jindong Song","doi":"10.1007/s10950-024-10224-5","DOIUrl":"10.1007/s10950-024-10224-5","url":null,"abstract":"<div><p>Rapid and accurate estimation of emergency response parameters during earthquakes is important in earthquake early warning (EEW) systems. Because earthquake rupture is not instantaneous, to accurately, safely, and reliably determine parameters and thresholds for emergency response, the cumulative absolute velocity (CAV) is used as the target parameter, and 7 P-wave characteristic parameters of strong ground motion records occurring 3 s after P-wave arrival at K-NET and KiK-net stations in Japan are used as inputs to construct a machine learning (ML) CAV prediction model based on the support vector machine (SVM) algorithm. The results show that compared with a single-parameter prediction algorithm, the proposed ML model can significantly reduce the error standard deviation and effectively address the phenomena of small value overestimation and large value underestimation. A confusion matrix analysis demonstrates that the 6-parameter model P_a&amp;P_v&amp;P_d&amp;CAV&amp;I_a&amp;IV2 shows the best performance in improving the prediction accuracy and provides a threshold selection strategy for threshold-based EEW emergency response.</p></div>","PeriodicalId":16994,"journal":{"name":"Journal of Seismology","volume":"28 3","pages":"811 - 828"},"PeriodicalIF":1.6,"publicationDate":"2024-06-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141254071","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}