The Research Of Epicenter Locating Methods In Earthquake Early Warning System

Earthquake location is one of the most basic problems of earthquake early warning.So far,there are many kinds of methods of earthquake location^[3],in the early time,the geometric methods occur such as intersection method,the advantage of geometric method is simple and intuitive.Lately Geiger's method^[4]appears,and following the main event method^[4],the method based on genetic algorithm^[6],these methods won the great development with the improvement of computational ability brought by the develop-ment of computer technology,the advantage of these methods is that the result is more accurate,while their computationally time-consuming is more long.The requirement of reducing time in an Earthquake early warning system is very strict,because the shorter the time using for estimating earthquake parameters is,the longer time the earthquake early warning system could provide,the more damage can mitigate.The real-time locating method is necessary for earthquake early warning.There are some real-time methods of earthquake locating,such as method using a sub array of two station^[7],the method based on Voronoi diagram^[8],method based on seismic amplitude attenuation^[9].These methods have advantages and disadvantages,for example,method based on seismic amplitude attenuation is simple and feasible,but the result is bad,so far it is out of the use of earthquake early warning system.earthquake location method based on Voronoi diagram of computational geometry is a fast and accurate locating method,the algorithm is not affected by velocity structure model,only the arrival time orders of P wave to the stations,it needs less stations,and calculate fast.These characteristics suits the needs of earthquake early warning system,which requires locating earthquake to give warning information as soon as possible,epicenter location is therefore suitable for earthquake early warning system.But this method has some problems,especially the heavy reliance on the arrival time order,making this method almost not practical.This paper improves the practicability of this method,locating earthquake by using seismic records of KiK-net,it verify the effectiveness of the method.The main contents of this paper are as follows:Firstly I introduce the history and principle of earthquake early warning technology,the status of the earthquake early warning system and abroad.Then I make a brief introduction of ordinary earthquake location methods,introduce the current main real-time earthquake location methods,and their advantages and disadvantages.After the introduction of the principle of method of Voronoi,I points out the existing problems of this method.To solve these problems,I make improvements for the old method,and provide a new method.Finally the verification using actual examples in kik-net shows its effectiveness.