Foreshocks of the 2016 MS5.1 Yunlong earthquake in Western Yunnan, China, and implications for earthquake nucleation

IF 1.2 4区地球科学 Q3 Earth and Planetary Sciences

Earthquake Science Pub Date : 2025-06-25 DOI:10.1016/j.eqs.2025.03.003

Gaohua Zhu , Hongfeng Yang , Yingying Zhang

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Abstract

Monitoring the evolution of foreshocks can be a valuable way to analyze the nucleation process. Foreshocks accompanying moderate mainshocks have been recorded in the west of Yunnan Province, China. We obtain the earthquake catalog and source parameters of the 2016 Yunlong foreshocks, and discuss the implications for the nucleation processes of the earthquake in western Yunnan, China. By using the matched filter detection, we identify 343 foreshocks with a magnitude of −0.8−4.5, starting with a magnitude 1.0 foreshock approximately 3 months before the 2016 M_S5.1 Yunlong mainshock. The spatial distribution of foreshocks doesn’t show localization or directional migration towards the mainshock. Coulomb stress analysis suggests a positive stress perturbation at the mainshock nucleate area. These observations indicate a cascade-triggering mechanism of the 2016 Yunlong earthquakes. We further collect published catalogs of 2021 Yangbi and 2017 Yangbi foreshocks in the adjacent area, and analyze the temporal changes in b values. The temporal changes in b values reveal precursory drops before the mainshocks.

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2016年云南西部云龙MS5.1地震前震及其成核意义

监测前震的演化是分析成核过程的一种有价值的方法。中国云南西部地区曾记录到伴有中度主震的前震。获得了2016年云龙前震的地震目录和震源参数，并讨论了其对滇西地震成核过程的启示。通过匹配滤波检测，我们确定了343次震级为- 0.8 - 4.5的前震，从一次震级为1.0的前震开始，大约在2016年MS5.1云龙主震发生前3个月。前震的空间分布不表现出向主震的局域化或定向迁移。库仑应力分析表明主震核区存在正应力扰动。这些观测结果表明了2016年云龙地震的级联触发机制。进一步收集邻区已公布的2021年杨壁和2017年杨壁前震目录，分析b值的时间变化。b值的时间变化揭示了主震前的前兆下降。

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来源期刊

Earthquake Science GEOCHEMISTRY & GEOPHYSICS-

CiteScore

1.10

自引率

8.30%

发文量

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.