Study On Regional Earthquake Location With Grid Search Method

Earthquake location is one of the most basic and classical problems in seismology.It is of great significance to study the distribution of seismically active tectonic belts,focal mechanism,seismogenic structure,earthquake disaster warning and internal structure of the earth.In this paper,the grid search algorithm is mainly used to solve the problem of regional earthquake rapid location,and the subsequent(sPn)seismic phase travel time information is used to realize the optimization of two different earthquake location methods within and outside the network,especially the optimal location of the focal depth.The v-diagram method is introduced into the earthquake location within the network to restrict the search area,which is different from the traditional method and takes the station elevation and underground velocity inhomogeneity into account.The location algorithm is more practical and greatly reduces the computing time of the traditional grid search method.By estimating the azimuth and epicentre distance,the earthquake location outside the network can reduce the area of the target source,avoid the global search in a wide range,and improve the efficiency of earthquake location.In synthetic numerical simulation positioning,the positioning results of different seismic phase combinations are compared and analyzed,and the constraint effect of various combinations in different source focus depth is discussed.The accuracy of earthquake location under three-dimensional velocity model is also discussed.The validity and accuracy of the proposed method are verified by locating the actual seismic data in Shaanxi and Shanxi province.Finally,the computational efficiency of the proposed method in actual earthquake location is analyzed,and the results show that the grid search algorithm has a global solution,high efficiency and high location accuracy.