Study on the crustal stress field of the Tengchong volcanic area using composite focal mechanism method
Study on the crustal stress field of the Tengchong volcanic area using composite focal mechanism method
复制标题
DOI：
10.1007/s11770-021-0897-z
复制
发表时间：
2021-06
影响因子：
0.7
通讯作者：
S. Sheng;Y. Wan;Chang-Sheng Jiang;Xiao-shan Wang;Shan-shan Liang;G. Xiao;Xiao-hui Hu
中科院分区：
文献类型：
--
作者：
S. Sheng;Y. Wan;Chang-Sheng Jiang;Xiao-shan Wang;Shan-shan Liang;G. Xiao;Xiao-hui Hu
利用《中国台站地震观测公报》2011年1月至2019年4月腾冲火山区P波初动极性资料，采用复合震源机制方法计算了腾冲火山区地壳应力场。本次研究所用地震震级范围为0-4级，震级主要在1.0级左右。为了研究震源位置对应力场的影响，获得研究区可靠的应力场，采用双差算法对地震同相轴进行了重定位，获得了更加准确可靠的地震同相轴相对位置，地震条带更加清晰。在重定位结果的基础上，对断裂带沿着的应力场进行了研究，分析了地震同相轴位置对应力场的影响。结果表明，腾冲火山区地壳浅部现今应力体制为走滑断裂，主压应力轴方向为NE-SW向，主拉应力轴方向为SE-NW向，主压应力轴和主拉应力轴近水平，中间主应力轴倾角较大。这反映了腾冲火山区的火山活动和地震活动主要受印度-欧亚板块的碰撞挤压作用控制。这也反映了深部岩浆活动引起的现今张拉作用对地壳浅部应力场的影响很小。其次，沿沿着断裂带的应力场揭示了局部应力场的存在，如走滑断层末端区的逆冲应力体制，这与前人研究指出的共轭走滑断层交汇处的挤压区相一致。第三，无论采用公报中的原始位置还是重新定位的位置，应力场结果都是一致的，说明在资料充足的情况下，事件定位误差的影响可以忽略不计，反映了复合震源机制方法的稳定性。研究结果可为腾冲火山区地质构造运动、地震活动和火山活动研究提供参考。
We calculated the crustal stress field using the composite focal mechanism method based on the P-wave initial motion polarity data of the Tengchong volcanic area from January 2011 to April 2019 obtained from the Bulletin of Seismological Observations of Chinese stations. The magnitude range of earthquakes used in this study is 0–4, and their magnitudes are mainly approximately 1.0. To investigate the influence of the source location on the stress field and obtain reliable stress fields of the study area, we applied the double-difference algorithm to relocate the seismic events, obtaining more accurate and reliable relative positions of seismic events with a clearer seismic belt. On the basis of relocation results, the study on the stress field along the fault zone was conducted, and the influence of seismic event position on the stress field was analyzed. Results show that, first, the current stress regime in the shallow crust of the Tengchong volcanic area is strike-slip faulting, the orientation of the principal compressive stress axis is NE-SW, the orientation of the principal extension stress axis is SE-NW, the principal compressive and extension stress axes are nearly horizontal, and the dip angle of intermediate principal stress axis is relatively large. This reflects that the volcanic and seismic activities in the Tengchong volcanic area are mainly controlled by the collision and squeezing effect of the Indian-Eurasian plate. It also reflects that the current tensile action caused by deep magma activity has little influence on the shallow crustal stress field. Second, the stress field along fault zones reveals that there exist local stress fields, such as the thrust stress regime at the strike-slip fault terminal area, which is consistent with the compressional area at the intersection of conjugate strike-slip faults indicated by previous study. Third, the stress field results are consistent, regardless of using the original location in the bulletin or the relocated location, indicating that the influence of the event location error can be neglected when there are sufficient data and reflecting the stability of the composite focal mechanism method. The findings can serve as a reference for investigating geological structure movement, seismic activities, and volcanic activities in the Tengchong volcanic area.