近震全波形反演2017年九寨沟M7.0地震序列震源机制解

近震全波形反演2017年九寨沟M7.0地震序列震源机制解杨宜海;范军;花茜;高见;王朝亮;周鲁;赵韬
【期刊名称】《地球物理学报》
【年(卷),期】2017(060)010
【摘要】搜集了四川地震台网的波形资料,采用全波形反演2017年8月8日九寨沟M7.0地震序列震源机制解.反演结果显示,九寨沟主震矩震级为Mw6.36,震源深度为22 km,节面Ⅰ走向为150°,倾角为80°,滑动角为-20°;节面Ⅱ走向为244°,倾角为70°,滑动角为-169°.余震主要分布在14～22 km深度范围内,震源机制以走滑型为主,其中正断型地震2个,逆冲型地震2个,走滑型地震24个,混合型地震8个.断层面优势方向为SSE向,与塔藏断裂和虎牙断裂走向基本一致,但与塔藏断裂最南段存在明显差异.倾角变化集中在60°～80°,滑动角主要分布在0°附近,表明九寨沟地震序列主要受SSE走向、近似直立的左旋走滑断层控制.P轴优势方位为SEE向,仰角主要分布在30°以内,与区域应力场基本一致.震源区的机制类型和应力状态均存在空间分段差异.本文推测此次九寨沟M7.0地震序列可能发生在虎牙断裂向北延伸的隐伏断裂上,但不排除地震引起了塔藏断裂南段和虎牙断裂以北隐伏断裂同时破裂的可能.%In this paper,we apply the full waveform inversion to determine the focal mechanisms of the 2017 Jiuzhaigou M7.0 earthquake sequence using near-field waveforms from Sichuan Seismic Network.Focal mechanism solutions show that the Jiuzhaigou M7.0 mainshock's moment magnitude is 6.36 and the depth is about 22 km.The two nodal planes' parameters are..strike=150°,dip=80°,rake=-20°;and
strike=244°,dip=70°,and rake=-169°.The aftershock sequences are located
in the depth range of 14～22 km,and focal mechanisms of the Jiuzhaigou event sequence are dominated by strike-slip faulting,of which 2 are normal,2 are thrust,24 are strike-slip,and 8 are mixed faulting.Strikes of fault planes are mostly in SSE direction,consistent with the trend of the Tazang fault and Huya fault,but different from the strike of southernmost part of the Tazang fault.The dip angles are in the range of 60°～80°,and rake angles are largely close to 0°,indicating the Jiuzhaigou earthquake sequence is under the control of the SEE-striking,approximately vertical left-lateral strike-slip fault.The azimuths of P-axes are mostly in SEE direction,and the plunges of P-axes are mostly less than 30°,generally coincide with the regional tectonic stress field.Focal mechanisms and stresses vary between various segments in the space.We infer that the seismogenic fault of the Jiuzhaigou earthquake sequence is a blind fault extending northward from the Huya fault.However,we can not rule out the possibility that the rupture of the southern segment of the Tazang fault and the blind fault to the north of Huya fault may both contributed to the Jiuzhaigou earthquake.
【总页数】7页(P4098-4104)
【作者】杨宜海;范军;花茜;高见;王朝亮;周鲁;赵韬
【作者单位】陕西省地震局,西安710068;四川省地震局,成都610041;陕西省地震局,西安710068;重庆市地震局,重庆401147;成都理工大学地球物理学院,成都610059;成都理工大学地球物理学院,成都610059;陕西省地震局,西安710068
【正文语种】中文
【中图分类】P315
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