Gorkha earthquake (MW7.8) and aftershock sequence: A fractal approach

IF 1.2 4区 地球科学 Q3 Earth and Planetary Sciences
Ram Krishna Tiwari , Harihar Paudyal
{"title":"Gorkha earthquake (MW7.8) and aftershock sequence: A fractal approach","authors":"Ram Krishna Tiwari ,&nbsp;Harihar Paudyal","doi":"10.1016/j.eqs.2022.06.001","DOIUrl":null,"url":null,"abstract":"<div><p>On April 25, 2015, Nepal was struck by the <em>M</em><sub>W</sub>7.8 Gorkha earthquake followed by an intense aftershock sequence. It was one of the most destructive earthquakes in the Himalayan arc, causing more than 8900 fatalities. In this study, we analyzed the dataset (429 events, magnitude of completeness (<em>M</em><sub>c</sub>) ≥ 4.2 local magnitude) of the first 45 days after the Gorkha earthquake to estimate the seismicity parameters <em>b</em>-value, <em>D</em>-value, and <em>p</em>-value. We used the maximum likelihood method to estimate the <em>b</em>-value and Omori-Utsu parameters, whereas the correlation integral method was applied to estimate the fractal dimension (<em>D</em>-value). The analysis was carried out using running and sliding window techniques. The lowest <em>b</em>-value (0.57 ± 0.04) and the highest <em>D</em>-value (1.65 ± 0.02) were computed at the time of the Gorkha earthquake, after which the <em>b</em>-value significantly increased to a maximum of 1.57. It again dropped to 0.93 at the time of the major aftershock on May 12, 2015. The <em>D</em>-value showed an initial quick drop and then decreased in a wavy pattern until the end of the study period, indicating the clustering and scattering of earthquakes in a fault region. The <em>b</em>-value contour map identified the eastern part of the study area as a high stress region (<em>b</em> = ∼0.8), implying that the stress shifted to that region. The <em>D</em>-value contour map reveals that the seismogenic structure shifted from linear to planar in the region. The rate of aftershock decay (<em>p</em> = 0.86 ± 0.04) for a short period reflects that the level of stress decreased rapidly. This study helps to understand the level of stress and seismicity pattern of a region, which could be useful for aftershock studies.</p></div>","PeriodicalId":46333,"journal":{"name":"Earthquake Science","volume":"35 3","pages":"Pages 193-204"},"PeriodicalIF":1.2000,"publicationDate":"2022-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S1674451922000416/pdfft?md5=4dd390e64439d402ed5015c95618b61c&pid=1-s2.0-S1674451922000416-main.pdf","citationCount":"1","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Earthquake Science","FirstCategoryId":"89","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S1674451922000416","RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"Earth and Planetary Sciences","Score":null,"Total":0}
引用次数: 1

Abstract

On April 25, 2015, Nepal was struck by the MW7.8 Gorkha earthquake followed by an intense aftershock sequence. It was one of the most destructive earthquakes in the Himalayan arc, causing more than 8900 fatalities. In this study, we analyzed the dataset (429 events, magnitude of completeness (Mc) ≥ 4.2 local magnitude) of the first 45 days after the Gorkha earthquake to estimate the seismicity parameters b-value, D-value, and p-value. We used the maximum likelihood method to estimate the b-value and Omori-Utsu parameters, whereas the correlation integral method was applied to estimate the fractal dimension (D-value). The analysis was carried out using running and sliding window techniques. The lowest b-value (0.57 ± 0.04) and the highest D-value (1.65 ± 0.02) were computed at the time of the Gorkha earthquake, after which the b-value significantly increased to a maximum of 1.57. It again dropped to 0.93 at the time of the major aftershock on May 12, 2015. The D-value showed an initial quick drop and then decreased in a wavy pattern until the end of the study period, indicating the clustering and scattering of earthquakes in a fault region. The b-value contour map identified the eastern part of the study area as a high stress region (b = ∼0.8), implying that the stress shifted to that region. The D-value contour map reveals that the seismogenic structure shifted from linear to planar in the region. The rate of aftershock decay (p = 0.86 ± 0.04) for a short period reflects that the level of stress decreased rapidly. This study helps to understand the level of stress and seismicity pattern of a region, which could be useful for aftershock studies.

廓尔喀地震(MW7.8)与余震序列:分形方法
2015年4月25日,尼泊尔发生了7.8级廓尔喀地震,随后发生了强烈的余震。这是喜马拉雅弧形地带最具破坏性的地震之一,造成8900多人死亡。本文分析了廓尔喀地震发生后45天的429个事件数据集(完整震级(Mc)≥4.2局地震级),估算了地震活动性参数b值、d值和p值。我们使用极大似然法估计b值和Omori-Utsu参数,而使用相关积分法估计分形维数(d值)。分析采用运行和滑动窗口技术。廓尔喀地震发生时b值最低(0.57±0.04),d值最高(1.65±0.02),地震发生后b值显著增加,最大值为1.57。2015年5月12日发生大余震时,该指数再次降至0.93。d值先是快速下降,然后呈波浪状下降,直到研究结束,这表明地震在断裂带具有聚集性和分散性。b值等值线图将研究区东部确定为高应力区(b = ~ 0.8),表明应力向该区域转移。d值等高线图显示,该区孕震构造由直线向平面转变。短时间内的余震衰减率(p = 0.86±0.04)反映应力水平迅速下降。这项研究有助于了解一个地区的应力水平和地震活动模式,这可能对余震研究有用。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
求助全文
约1分钟内获得全文 求助全文
来源期刊
Earthquake Science
Earthquake Science GEOCHEMISTRY & GEOPHYSICS-
CiteScore
1.10
自引率
8.30%
发文量
42
审稿时长
3 months
期刊介绍: Earthquake Science (EQS) aims to publish high-quality, original, peer-reviewed articles on earthquake-related research subjects. It is an English international journal sponsored by the Seismological Society of China and the Institute of Geophysics, China Earthquake Administration. The topics include, but not limited to, the following ● Seismic sources of all kinds. ● Earth structure at all scales. ● Seismotectonics. ● New methods and theoretical seismology. ● Strong ground motion. ● Seismic phenomena of all kinds. ● Seismic hazards, earthquake forecasting and prediction. ● Seismic instrumentation. ● Significant recent or past seismic events. ● Documentation of recent seismic events or important observations. ● Descriptions of field deployments, new methods, and available software tools. The types of manuscripts include the following. There is no length requirement, except for the Short Notes. 【Articles】 Original contributions that have not been published elsewhere. 【Short Notes】 Short papers of recent events or topics that warrant rapid peer reviews and publications. Limited to 4 publication pages. 【Rapid Communications】 Significant contributions that warrant rapid peer reviews and publications. 【Review Articles】Review articles are by invitation only. Please contact the editorial office and editors for possible proposals. 【Toolboxes】 Descriptions of novel numerical methods and associated computer codes. 【Data Products】 Documentation of datasets of various kinds that are interested to the community and available for open access (field data, processed data, synthetic data, or models). 【Opinions】Views on important topics and future directions in earthquake science. 【Comments and Replies】Commentaries on a recently published EQS paper is welcome. The authors of the paper commented will be invited to reply. Both the Comment and the Reply are subject to peer review.
×
引用
GB/T 7714-2015
复制
MLA
复制
APA
复制
导出至
BibTeX EndNote RefMan NoteFirst NoteExpress
×
提示
您的信息不完整,为了账户安全,请先补充。
现在去补充
×
提示
您因"违规操作"
具体请查看互助需知
我知道了
×
提示
确定
请完成安全验证×
copy
已复制链接
快去分享给好友吧!
我知道了
右上角分享
点击右上角分享
0
联系我们:info@booksci.cn Book学术提供免费学术资源搜索服务,方便国内外学者检索中英文文献。致力于提供最便捷和优质的服务体验。 Copyright © 2023 布克学术 All rights reserved.
京ICP备2023020795号-1
ghs 京公网安备 11010802042870号
Book学术文献互助
Book学术文献互助群
群 号:481959085
Book学术官方微信