2018年7月10日河南固始ML 4.0地震震源参数与发震构造分析

2018年7月10日河南固始发生M_L 4.0地震，为区域4级地震平静长达18年背景下的一次显著事件。为分析此次地震震源破裂性质和发震构造特征，采用Snoke方法计算震源机制解，结果显示，震源错动类型以正断为主兼具走滑，其中节面Ⅰ：走向127.0°，倾角75.0°，滑动角-78.0°；节面Ⅱ：走向268.0°，倾角19.0°，滑动角-128.0°，且节面Ⅰ性质与淮滨断裂破裂特征和切错方式符合；采用震源谱拟合计算得到此次地震应力降为2.756 MPa，固始及邻区M_L 2.5-4.0地震应力降普遍小于3 MPa，且与震级存在一定正相关关系。

Analysis on focal parameters and seismogenic structures of Gushi ML 4.0 earthquake in Henan Province on July 10, 2018

On July 10, 2018, Gushi M_L 4.0 earthquake occurred under the background of long-term peace for 4 magnitude of earthquake. We calculated the focal mechanism solution by Snoke method. The result shows that the source rupture type is given priority to with normal fault. The focal mechanism solution is similar to the fracture feature and cutting mod of Huaibin fault which is the nearest one to the epicenter. Using the method of source spectrum fitting, we gained the stress drop (2.756 MPa) and we find that the stress drop of M_L 2.5-4.0 earthquakes in Gushi country and adjacent regions are generally less than 3 MPa. The linear fitting result shows that there are positive correlation relationship between stress drop and magnitude.