张云鹏^1,,
王宝善^1,2,3,,,
林国庆⁴,
王伟涛¹,
杨微¹,
吴中海⁵
1. 中国地震局地球物理研究所, 北京 100081
2. 中国科学技术大学地球和空间科学学院, 合肥 230026
3. 中国科学技术大学安徽蒙城地球物理国家野外科学观测研究站, 合肥 230026
4. 美国迈阿密大学罗森斯蒂尔海洋与大气科学学院, 佛罗里达州迈阿密 33149
5. 新构造运动与地质灾害重点实验室, 中国地质科学院地质力学研究所, 北京 100081

基金项目: 国家重点研发计划（2016YFE0109300和2018YFC1503200），国家自然科学基金（41790462和41974069），中国地震局中国地震科学实验场项目（2018CSES0101），中国地震局地球物理研究所基本科研业务费专项（DQJB19B32）和云南省陈颙院士工作站（2014IC007）联合资助


详细信息

作者简介: 张云鹏, 女, 1991年生, 中国地震局地球物理研究所在读博士, 主要从事主动震源探测和体波层析成像研究.E-mail:zhangyp@cea-igp.ac.cn

通讯作者: 王宝善, 男, 1976年生, 中国科学技术大学地球和空间科学学院教授, 主要从事地球内部精细结构及其随时间变化的研究、新型地震观测和主动震源探测技术.E-mail:bwgeo@ustc.edu.cn

中图分类号: P315

收稿日期:2020-01-02
修回日期:2020-02-18
上线日期:2020-09-05

Upper crustal velocity structure of Binchuan, Yunnan revealed by dense array local seismic tomography

ZHANG YunPeng^1,,
WANG BaoShan^1,2,3,,,
LIN GuoQing⁴,
WANG WeiTao¹,
YANG Wei¹,
WU ZhongHai⁵
1. Institute of Geophysics, China Earthquake Administration, Beijing 100081, China
2. School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026, China
3. Mengcheng National Geophysical Observatory, University of Science and Technology of China, Hefei 230026, China
4. Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, FL 33149, USA
5. Key Laboratory of Neotectonic Movement & Geohazard, Institute of Geomechanics, Chinese Academy of Geological Sciences, Beijing 100081, China


More Information

Corresponding author: WANG BaoShan,E-mail:bwgeo@ustc.edu.cn

MSC: P315

--> Received Date: 02 January 2020
Revised Date: 18 February 2020
Available Online: 05 September 2020


摘要
摘要:滇西北宾川盆地是发育于红河断裂和程海断裂交汇处的晚新生代张扭断陷盆地，该区活动断裂发育且历史地震比较活跃.对宾川盆地及邻区进行高精度浅层和上地壳精细结构研究，有助于深入认识该区主要发震构造的深浅部特征.基于2017年在宾川盆地及其附近开展的为期2个月的密集台阵观测数据，我们对该区96个小震共拾取了117221条初至P波和5475条初至S波震相，并利用simul2000开展了地震重定位和体波层析成像研究.结果表明：（1）小震活动主要集中在宾川盆地东缘断裂的弧形转折部位，并在洱海南侧呈现沿北东向断裂的条带状分布现象，反映了区域上近南北向至北东向断裂是主要控震构造，其次是北西向断裂带.（2）0 km的速度分布与区域地形有很好的对应关系.山地呈现高速异常，宾川盆地呈现低速异常.从3 km至9 km，高低速分界与断层有很好的对应，并且越往深部，近南北向至北北东向的宾川盆地东缘断裂在上地壳构造的控制作用越明显.（3）上地壳层析成像结果同时揭示了宾川盆地东缘断裂的三维形态变化在空间上呈现出南北部倾角大、中部倾角缓的变化特征，可能与区域地块的旋转变形过程有关.（4）综合高精度浅层速度结构和地震重定位结果可知，区域上的近南北向至北北东向断裂正逐步取代北西向构造，成为主要的区域分界断裂和控震构造.新的研究结果为深入理解该区的主要控震构造及其深部结构特征提供了重要依据.
关键词: 云南宾川/
程海断裂/
气枪震源/
体波层析成像/
地震重定位

Abstract:The Binchuan basin, located in northwestern of Yunnan Province, is a large Late Cenozoic rift basin at the intersection of the Red River fault and Chenghai fault. The faults are well developed and the seismicity is very active in this area. Studying the fine structure of the upper crust and basin in Binchuan is important to understand the characteristics from deep to shallow of the main seismic structures in this area. Based on the dense array observation experiment around Binchuan basin for two months in 2017, we picked 117221 P-wave and 5475 S-wave first arrivals from 96 small local earthquakes, and performed earthquake relocation and body-wave tomography using the simul2000 program. The obtained results show that (1) the earthquakes in the Binchuan basin are concentrated at the turning area of the Binchuan basin eastern margin fault and show a banding distribution along the NE trending fault on the southern edge of the Erhai Lake, which indicate that NS-NE trending faults are the main seismic control structures and the NW trending faults are the secondary. (2) The velocity distribution at 0 km has a good correspondence with local topography, with high-velocity anomalies in the mountains and low-velocity anomalies in the Binchuan basin. From 3 km to 9 km, the high-low velocity boundaries correspond well to local faults. The controlling effect in the upper crustal structure of the Binchuan basin eastern margin fault (near NS-NNE trending) becomes more and more obvious with depth. (3) Our results also reveal that the dipping angle of Binchuan basin eastern margin fault is large in the northern and the southern portions, however, is gentle in the middle portion, reflecting the rotation characteristics of the regional tectonic block. (4) Relocation and tomographic results indicate that near NS and NNE trending faults are gradually replacing the NW trending faults as the main boundary faults and the main seismic control structures. Our new study results provide an important reference to better understand the main seismic-controlling structures and their deep structural features.
Key words:Binchuan/
Chenghai fault/
Airgun/
Body-wave tomography/
Earthquake relocation



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