2012年以来新丰江水库区地震震源机制解及构造应力场时空变化特征

doi:10.12196/j.issn.1000-3274.2022.03.005

摘要/Abstract

摘要： 研究新丰江水库地震活动和震源机制及区域构造应力场分布, 对理解新丰江库区诱发地震的特点和成因机理有着重要的意义。基于2012—2018年新丰江库区M_L2.0及以上地震的142个地震波形数据, 分别采用FOCMEC方法和SATSI方法反演了中小地震震源机制解和区域应力场, 并对其时空变化特征进行了研究。结果表明: 新丰江库区地震破裂类型以正断型为主, 兼有部分倾滑分量, 其次为走滑型; P轴优势走向为NWW—SEE向, 倾角近于垂直, T轴优势走向为NNE—SSW向, 倾角近乎水平; 库区整体以NWW—SEE向的垂直挤压和NNE—SSW向的水平拉伸为主, 应力类型为正断型; 由东南部NW—SE向至西北部的NWW—SEE向, 最大主应力轴方向呈现逆时针旋转的趋势, 旋转角度约为18°, 应力类型也由正断型转变为走滑型; 2012年以来, 新丰江各区域的应力场较为稳定, 但在2015年和2018年可能发生过相对较大的变化, 这种变化是否存在, 依据现有结果仍不得而知, 需要在以后的研究中进一步验证。

关键词: 新丰江库区, 震源机制, 构造应力场, FOCMEC, SATSI

Abstract: The seismic activity and the distribution of focal mechanism and tectonic stress filed are of great significance for understanding the characteristics and genetic mechanism of induced earthquakes in the Xinfengjiang reservoir. Based on 142 seismic events (M_L≥2.0, 2012—2018), we calculated the focal mechanism solutions with FOCMEC method and invert the regional stress field with SATSI method. Then, we discussed the spatio-temporal variation of the tectonic stress field in Xinfengjiang reservoir. The results show that the earthquake rupture type in Xinfengjiang reservoir is mainly normal-faulting type with partial dip-slip components, and the second is strike-slip type. The advantageous directions of P-axis are NWW—SEE, and the plunge is close to vertical; the advantageous directions of T-axis are NNE—SSW, and the plunge is close to horizontal. The entire reservoir is mainly under action of the vertical extrusion of NWW—SEE and the horizontal stretching of NNE—SSW, and the stress is of normal-faulting type. From the NW—SE direction in the southeast to the NWW—SEE direction in the northwest, the maximum principal stress axis shows a counterclockwise rotation, with the rotation angle of about 18°, and the type of stress filed is changed from normal-faulting to strike-slip. Since 2012, the stress field of various regions in Xinfengjiang reservoir has been in a relatively stable state, but relatively large changes may occur in 2015 and 2018. Whether there is any variations of maximum principal stress axis in the studied region is unknown according to present calculation results, which need to be further verified.

Key words: Xinfengjiang reservoir, Focal mechanism, Tectonic stress field, FOCMEC, SATSI

中图分类号:

P315.7

姜喜姣, 林庆西, 龚萱, 杨选. 2012年以来新丰江水库区地震震源机制解及构造应力场时空变化特征[J]. 地震, 2022, 42(3): 64-80.

JIANG Xi-jiao, LIN Qing-xi, GONG Xuan, YANG Xuan. Earthquake Focal Mechanism Solutions and Spatio-temporal Variations of Tectonic Stress Field in Xinfengjiang Reservoir since 2012[J]. EARTHQUAKE, 2022, 42(3): 64-80.

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