Earthquake location derived from P, PmP and S waves : feasibility and problems

Abstract

In this research, we explore variety of methods to locate earthquakes in Kyushu Japan and Southern California.

Locating earthquakes to identify a fault line, is one of the possible way to find a cause of an earthquake occurrence. Although an earthquake occurrence is inevitable and unpredictable in general, at least the scientist will know that sometime later, the similar earthquake will occur again somewhere within a fault line, and therefore need to plan and be prepared in advance to prevent similar casualties again.

To find each earthquake location, at least 4 seismic stations locations and their corresponding phase arrival times should be known. In practice, there are usually more than 4 seismic stations for each earthquake and each phase arrival time is manually picked with some error, and hence requires to find the best fit approximation of each earthquake location. In this research thesis, we use Geiger's Method, and Grid Search and Fast Marching Method to locate earthquake.

Overall, both Geiger's Method, and Grid Search and Fast Marching Method, are feasible for locating epicenter of earthquakes. However, for both methods, we need to be careful when locating earthquake depth. Because the earthquake depth estimate might be very uncertain and the error estimate must be checked.