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2017年5月16日四川石渠Ms4.4级地震震源机制及发震构造分析
杨彦明, 王树波, 苏日亚
内蒙古自治区地震局
摘要:
本文利用四川、青海、西藏和甘肃区域数字地震台网波形数据,采用gCAP反演方法,获得2017年5月16日四川石渠Ms4.4级地震的震源机制解。最佳双力偶解为节面Ⅰ走向214°,倾角80°,滑动角167°;节面Ⅱ走向306°,倾角77°,滑动角10°;最佳质心深度为7.3±0.6 km,矩震级为Mw4.52。为测试震源机制解的稳定性和可靠性,对地壳速度结构、定位误差、数据质量和地震参数差异的影响等4个方面进行分析,研究认为,这些因素对反演结果影响较小。根据震源区地质构造特征、余震序列的空间分布特征、区域构造应力场特征,结合主震震源机制解,初步判断此次地震断层面为节面Ⅱ,发震断层为长沙贡玛断裂,此次石渠地震为以左旋走滑为主的地震事件。
关键词:  四川石渠  震源机制  发震构造  青藏高原  鲜水河断裂带
DOI:
分类号:
基金项目:内蒙古自治区地震局局长基金重点项目(2020TM04);内蒙古自治区地震局局长基金项目(2019JC27)
Focal Mechanism and Seismogenic Structure of the Shiqu Ms4.4 Earthquake, 16 May 2017 in Sichuan Province
yang yanming, Wang Shubo, Su riya
Earthquake Agency of Inner Mongolia Autonomous Region
Abstract:
The focal mechanism solution of the 16 May 2017 Shiqu Ms4.4 Earthquake in Sichuan Province was studied by the gCAP method using the observed waveform from the Sichuan, Qinghai, Tibet and Gansu Regional Seismic Networks. The strike/dip/slip of the first nodal plane are 214°/80°/167° and those of the second nodal plane are 306°/77°/10°, the optimal centroid depth is 7.3±0.6 km and the moment magnitude is Mw 4.52. We also investigated the result""s robustness against the error of crustal velocity structure, location, data quality and difference of seismic parameters, then found the resolved focal mechanism is stable. According to the characteristic of geologic structure in seismic source area , space distribution of aftershock sequence and characteristics of regional tectonic stress field, and combining focal mechanism of main shock, we conclude that the Shiqu earthquake shows left-lateral strike-slip mechanism and the second nodal plane is inferred to the seismogenic fault that agrees with the geometry of Changshagongma fault.
Key words:  Shiqu in Sichuan Province  focal mechanism  seismogenic structure  Tibet Plateau  Xianshuihe fault zone