利用双差层析成像方法研究辽宁海城-岫岩地区的精细速度结构

Using Double-Difference Tomography to Study the Fine Velocity Structure in Haicheng-Xiuyan Area of Liaoning

利用区域尺度的双差层析成像方法对2008-10~2020-04辽宁海城-岫岩地区地震事件进行震源位置和速度结构的联合反演。对剔除离散走时后的5028个地震事件进行重新定位,得到的震相走时均方根残差平均值由定位前的0.507 s降为0.279 s。重新定位后的结果显示:1)大部分地震发生于地下5~15 km,海城-岫岩地区地震活动多呈条带状分布于断裂带上,与海城河-大洋河断裂带走向吻合;2)反演得到的主要地震活动大部分分布在低速区及高速区与低速区交界地区,其中海城-岫岩震源区上地壳低速区的存在可能与所处断裂构造、深部流体等有关。

We use the regional-scale double-difference tomography method to perform a joint inversion of the source location and velocity structure of the seismic events recorded from October 2008 to April 2020 in the Haicheng-Xiuyan area of Liaoning province.After excluding the discrete travel time,a total of 5,028 seismic events are collected for positioning.We determine that the average value of the root mean square residual error of the seismic phase travel time decreases from 0.507 s before positioning to 0.279 s after positioning.The results of the relocation show:1)Most of the earthquakes occurred 5-15 km underground,and the seismic activity in the Haicheng-Xiuyan area was more concentrated in the geological structure and distributed on the fault zone in a strip form,which is similar to the Haichenghe-Dayanghe fault.2)The main seismic activities we obtain from the inversion are mainly distributed in the low-velocity area and the area at the junction of the high-speed body and the low-velocity body.This is related to the fault structure and deep fluid.