EPICENTER DISTANCE ESTIMATION METHOD WITH IMPROVED IMMEDIATE RESPONSIVENESS

PROBLEM TO BE SOLVED: To provide an epicenter distance estimation method with improved immediate responsiveness in which epicenter distance information can be estimated in earlier timing by watching time changes in values of A and B which are parameters of an earthquake waveform.SOLUTION: An epicenter distance estimation method with improved immediate responsiveness includes the steps of: canceling an offset from an observed earthquake wave; taking an absolute value of data; smoothing a waveform; fitting a function y=Bt×exp(-At) from a time of arrival of the earthquake wave to determine time changes in parameters of the expression; determining convergence of the parameters under such a condition that a differentiation value of the time change of the parameter is settled within a preset predetermined threshold value close to 0 continuously for a preset predetermined time; and determining an epicenter distance from the parameters on the basis of the determination.