不同一维速度模型的地震定位效果比较——以小江断裂带为例

Comparison of Earthquake Location Effect of Different 1D Velocity Model:Application to Xiaojiang Fault Zone

利用小江断裂带流动地震台阵的观测数据,使用三维速度模型对59个地震参考事件进行绝对定位。使用Hyposat和Hypoinverse两种地震定位方法以及三种一维速度模型进行了地震定位试验。试验结果表明:对于速度结构横向变化较小的区域,当一维速度模型基本合理时,两种定位方法都能得到比较准确的震中位置。与震中位置相比,震源深度对速度模型的依赖更大。基于一维速度模型的地震定位,应优先选择人工地震测深的速度模型。对于地震资料丰富的区域,使用"最小一维速度模型"方法确定的速度模型也可以提高地震定位的精度。

By using data recorded by dense temporary earthquake stations installed in the Xiaojiang fault zone,59 earthquake reference events were absolutely located by 3D velocity model. This paper used Hyposat and Hypoinverse earthquake location methods and three kinds of 1D velocity model to do earthquake location tests.Results reveal that： when the 1D velocity model is reasonable in the regions with smaller lateral variations of velocity structure, the two methods can obtain the exact epicenter. Compared with the epicenter, the depth of thesource is more dependent on the velocity model. The application of currently earthquake location methods based on 1D velocity model, we should try to choose the result of active source detection. By the Kissling method to obtain the ＂minimum 1D velocity model＂ in the region with rich seismic data, it can improve the accuracy of earthquake location.