High resolution catalog of the Luxian (Sichuan, China) MS6.0 earthquake sequence and analysis of the seismogenic structures

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

Earthquake Science Pub Date : 2025-02-01 DOI:10.1016/j.eqs.2024.09.004

Huili Guo , Dahu Li , Pingping Wu , Qiyan Yang , Ningbo Jiang , Mi Gao , Zhifeng Ding

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Abstract

The epicenter of the Luxian M_S6.0 earthquake on September 16, 2021, was located in the southern Sichuan Basin, which is a historically seismically quiescent area. In recent years, the frequency of earthquakes has increased with the large-scale exploitation of shale gas. No evident surface fractures or seismic faults were observed after the Luxian earthquake. Based on high-quality data recorded by a dense seismic array composed of 70 portable stations with an average spacing of 2–3 km, a high-resolution seismic catalog was constructed for 7 days before and 36 days after the M_S6.0 earthquake using LOC-FLOW, an effective workflow of phase picking, phase association, and earthquake location. Based on the new earthquake catalog, four earthquake clusters that occurred within the Yujiasi Syncline during this period were identified. Among them, the M_S6.0 main earthquake sequence had a NW-SE trend and inclined towards the SW, with a length of approximately 8 km and width of 5 km. The M_S6.0 earthquake sequence only appeared after the mainshock. The other three clusters were located in the northeast direction of the M_S6.0 earthquake sequence, all of which were NE-SW trending strips and had no evident direct correlation with the M_S6.0 mainshock. The focal depth was concentrated in the range of 2–7 km. Based on the seismic sequence profile and structural background, the M_S6.0 seismic structure may be a blind buried fault zone with a NW strike composed of multiple small conjugate faults with NE and SW dip. The fault was not exposed on the surface and was related to the detachment structure in the deep part of the Sichuan Basin.

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四川芦仙MS6.0级地震序列的高分辨率目录及发震构造分析

2021年9月16日发生的芦仙6.0级地震震中位于四川盆地南部，历史上属于地震静止区。近年来，随着页岩气的大规模开采，地震发生的频率有所增加。陆县地震后未发现明显的地表断裂或地震断层。基于70个平均间距为2 ~ 3 km的便携式台站密集地震台网记录的高质量数据，利用LOC-FLOW（相位采集、相位关联和地震定位的有效工作流程）构建了MS6.0地震前7天和后36天的高分辨率地震目录。根据新的地震目录，确定了这一时期发生在余家寺向斜内的4个地震群。其中，MS6.0主地震序列呈NW-SE走向，向西南方向倾斜，长约8 km，宽约5 km。MS6.0级地震序列只出现在主震之后。其余3个震群均位于MS6.0地震序列的东北方向，均为NE-SW向带状，与MS6.0主震没有明显的直接相关性。震源深度集中在2 ~ 7 km范围内。根据地震序列剖面和构造背景分析，MS6.0地震构造可能是一条北西向的盲隐断裂带，由多条北东向和西西向的小共轭断裂组成。该断裂表面不露，与四川盆地深部的滑脱构造有关。

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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.