2023 年图尔基耶双地震震源区剪切波分裂参数的变化

IF 1.2 4区 地球科学 Q3 Earth and Planetary Sciences
Xuelai Cao, Lijun Chang
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引用次数: 0

摘要

本研究在 2022 年 6 月 1 日至 2023 年 4 月 25 日期间测量了 2023 年图尔基耶 MW7.7 和 MW7.6 双联地震(分别为事件 1 和事件 2)震源区局部地震事件的剪切波分裂参数,并分析了其时空特征。结果显示出明显的时空差异。从空间上看,每个台站的主要快波极化方向与台站附近地震事件(MW≥3.5)的焦点机制解所表征的最大水平主压应力方向有很强的相关性。主要的快波极化方向和区域应力场也显示出与阿拉伯板块、非洲板块和安纳托利亚块体的相互移动密切相关。沿着事件 1 的地震断层 Nurdagi-Pazarcik 断层带,靠近发生主震的断层中部的台站的延迟时间明显大于位于断层两端和远离主震的台站。此外,位于 Nurdagi-Pazarcik 断层以东和 Sürgü 断层以北的站点也表现出较大的延迟时间。从各台站获得的剪切波分裂参数的空间分布来看,震源区上部地壳各向异性主要受区域应力场控制,与块体运动状态密切相关。在 MW7.7 地震的成震过程中,Nurdagi-Pazarcik 断层中部积累的应力大于断层两端。在 MW7.7 和 MW7.6 事件的影响下,地震双联发生过程中积累的应力可能在震后向余震密集区以外的一些地区迁移,外围台站附近的地壳应力及其调整范围明显增大。除两个有效事件较少的台站外,其他台站的剪切波分裂参数随时间的推移均有一致的变化。其中,各台站在双发地震后的延迟时间均呈减小趋势,反映出双发地震后成震区地壳应力调整明显加强。随着双发地震和大量余震的发生,双发地震成震过程中积累的应力逐渐释放,地壳应力的调整范围也随之逐渐减小。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
Variations of shear-wave splitting parameters in the source region of the 2023 Türkiye doublet earthquakes

In this study, the shear-wave splitting parameters of local seismic events from the source regions of the 2023 Türkiye MW7.7 and MW7.6 doublet earthquakes (event 1 and event 2, respectively) were measured from June 1, 2022, to April 25, 2023, and their spatiotemporal characteristics were analyzed. The results revealed clear spatial and temporal differences. Spatially, the dominant fast-wave polarization direction at each station shows a strong correlation with the direction of the maximum horizontal principal compressive stress, as characterized by focal mechanism solutions of seismic events (MW≥3.5) near the station. The dominant fast-wave polarization direction and the regional stress field also showed a strong correlation with the intermovement of the Arabian Plate, African Plate, and Anatolian Block. Along the Nurdagi-Pazarcik fault zone, the seismic fault of event 1, stations closer to the middle of the fault where the mainshock occurred exhibited notably greater delay times than stations located towards the ends of the fault and far from the mainshock. In addition, the stations located to the east of the Nurdagi-Pazarcik fault and to the north of the Sürgü fault also exhibited large delay times. The spatial distribution of shear-wave splitting parameters obtained from each station indicates that the upper-crust anisotropy in the source area is mainly controlled by the regional stress field, which is closely related to the state of the block motion. During the seismogenic process of the MW7.7 earthquake, more stress accumulated in the middle of the Nurdagi-Pazarcik fault than at either end of the fault. Under the influence of the MW7.7 and MW7.6 events, the stress that accumulated during the seismogenic process of the earthquake doublet may have migrated towards some areas outside the aftershock intensive area after the earthquakes, and the crustal stress and its adjustment range near the outer stations increased significantly. With the exception of two stations with few effective events, all stations showed a consistent change in shear-wave splitting parameters over time. In particular, each station showed a decreasing trend in delay times after the doublet earthquakes, reflecting the obvious intensification of crustal stress adjustment in the seismogenic zone after the doublet earthquakes. With the occurrence of the earthquake doublet and a large number of aftershocks, the stress accumulated during the seismogenic process of the doublet earthquakes is gradually released, and then the adjustment range of crustal stress is also gradually reduced.

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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.
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