四川康定地区小震群震源机制一致性变化特征

The Characteristics of Focal Mechanisms Consistency of Small Earthquake Swarm in Sichuan Kangding Area

利用体波谱振幅相关的方法,对2014年11月22日康定M6.3主震发生后至2015年1月31日期间ML≥1.6级余震序列的震源机制一致性进行研究。在震群不同方位共选取8个地震观测台站,以鲜水河断裂为界将地震台站分为西南侧与东北侧台站,利用不同台站组合计算平均相关系数。依地震发生时间顺序,将每5次地震事件分为一组,按照步长为1滑动求取平均相关系数。结果显示,由断裂东北侧台站计算出来的总体值最低,其次是由断裂西南侧台站计算结果,由8个台站计算所得的平均相关系数最高;由断裂带西南侧台站与由8个台站计算结果的变化特征类似,表现为随着时间推移跳跃、达到低点、升高后趋于稳定;而由断裂东北侧台站计算的结果表现为小副跳跃后达到低值并趋于稳定,这可能是由于深部构造及应力场的影响所致。

The method of spectral amplitude correlation is used to research the focal mechanism consistency of aftershocks sequences with ML≥1. 6 during 22 November 2014 when main shock Kangding M6. 3 occured to 30 April2015. A total of 8 stations are selected at different locations of the earthquake swarm and divided into southwest and northeast side stations with Xianshuihe Faults as the boundary. Average correlation coefficient is calculated by using the combination of different stations. According to the time order,the average correlation coefficient is calculated for every 5 events and the step length is 1. It is showed that the results from northeast stations is the lowest,followed by the results calculated by the southwest side stations and the average correlation coefficient calculated by the 8 stations of the highest. The variation of results with southwest stations and 8 sations is similar,which with the passage of time,jumping at low,increased and then tended to be stable. The trend based on northeast stations showed jumping a little to achieve low value and then tends to be stable. This may be due to the influence of deep structure and stress field.