Method for estimating distance parameter of observed earthquake, distance parameter estimation program, and computer-readable recording medium recording distance parameter estimation program

摘要

PROBLEM TO BE SOLVED: To provide a method for estimating a distance parameter of an observed earthquake, having high estimation accuracy of the distance parameter.SOLUTION: Preliminary tremors of past earthquake represented by vertical motion waveforms are extracted, a first frequency range of a relatively low frequency and a second frequency range of a relatively high frequency are set, and a spectrum intensity ratio in the two frequency range is calculated. The spectrum intensity ratio calculation is executed to vertical motion waveforms of plural earthquakes, and a correlation coefficient between a distance parameter corresponding to a vertical motion waveform of each earthquake and each spectrum intensity ratio is derived. Each of this step is repeated while changing the first frequency range and the second frequency range, and a first frequency range and a second frequency range in which a correlation coefficient becomes a maximum are determined to be a low frequency range and a high frequency range. Spectrum intensity of preliminary tremors of an observed earthquake within the low frequency range and the high frequency range are calculated so as to estimate a distance parameter of the observed earthquake by a primary expression of the spectrum ratio.SELECTED DRAWING: Figure 3