宜宾地区三维速度结构及震区构造特征*

全文: PDF (1572 KB) HTML ( KB) 输出: BibTeX | EndNote (RIS) 背景资料

摘要本文选取2009 年1 月-2019 年1 月期间宜宾及其周边地区56 个固定台站记录到的6085 个地震的84756 条P 波和S 波的初至绝对到时数据，利用双差层析成像方法联合反演宜宾地区的震源参数及其0-30km 深度的三维体波速度结构。结果显示，重定位后的地震空间分布与速度结构之间表现出很好的对应关系，主要集中在高速异常区或高速区边缘。宜宾地区P 波和S 波的速度结构均表现出明显的横向不均匀特性，在近地表处的分布特征与地貌、地质构造密切相关，在15-25km深度受下地壳流影响，出现明显低速异常。筠连县-珙县震区和珙县-长宁县震区是宜宾地区最为集中的两个地震频发地区，地震分布和构造特征存在明显不同。通过结合宜宾地区三维体波速度结构，对筠连县-珙县震区和珙县-长宁县震区构造特征的分析表明，虽然宜宾地区的大多地震活动是由流体注入引起的，但其地震活动的空间位置受中上地壳速度结构和局部地质构造的控制。宜宾地区的三维精细速度结构为深入了解该地区的地壳介质、发震构造和地震活动特征提供了重要的参考信息。

	服务

	把本文推荐给朋友
	加入我的书架
	加入引用管理器
	E-mail Alert
	RSS
	作者相关文章

关键词：宜宾地区双差层析成像三维P 波、S 波速度结构构造特征

Abstract： In this study, on the basis of absolute fi rst-arrival times of 84756 P- and S-waves from 6085 earthquakes recorded at 56 fi xed stations in Yibin and surrounding areas in China from January 2009 to January 2019, focal parameters and three-dimensional (3D) body-wave high-resolution velocity structures at depths of 0–30 km were retrieved by double-difference tomography. Results show that there is a good correspondence between the spatial distribution of the relocated earthquakes and velocity structures, which were concentrated mainly in the high-velocity-anomaly region or edge of high-velocity region. Velocity structure of P- and S-waves in the Yibin area clearly shows lateral inhomogeneity. The distribution characteristics of the P- and S-waves near the surface are closely related to the geomorphology and geologic structure. The low-velocity anomaly appears at the depth of 15–25 km, which is affected by the lower crust current. The Junlian–Gongxian and Gongxian–Changning earthquake areas, which are the two most earthquake-prone areas in the Yibin region, clearly differ in earthquake distribution and tectonic characteristics. We analyzed the structural characteristics of the Junlian–Gongxian and Gongxian–Changning earthquake areas on the basis of the 3D bodywave velocity structures in the Yibin region. We found that although most seismicity in the Yibin area is caused by fl uid injection, the spatial position of seismicity is controlled by the velocity structures of the middle and upper crust and local geologic structure. Fine-scale 3D velocity structures in the Yibin area provide important local reference information for further understanding the crustal medium, seismogenic structure, and seismicity.

Key words： Yibin area double-difference tomography method 3D P-wave and S-wave velocity structure structural characteristics

收稿日期: 2019-05-24;

基金资助:

天津市地震局科研项目（编号: yb201901）、中国地震局震情跟踪课题（编号: 2019010127）和中国地震局“监测、预测、科研"三结合课题（编号:3JH-201901006）联合资助.

通讯作者: 马永（E-mail:marvin.228@163.com） E-mail: Email: marvin.228@163.com

作者简介: 马永，工程师，2019 年毕业于中国科学技术大学地球和空间科学学院地质工程专业，硕士研究生学历，现就职于天津市地震局监测预报中心，主要从事地震层析成像和地震监测研究。Email:marvin.228@163.com

引用本文:

. 宜宾地区三维速度结构及震区构造特征*[J]. 应用地球物理, 2019, 16(3): 269-277.

. Three-dimensional velocity structure and tectonic characteristics of earthquake area in Yibin*[J]. APPLIED GEOPHYSICS, 2019, 16(3): 269-277.