Instrumental Intensity Assessment And Fault Rupture Length

This paper summarized and analyzed the estimation methods of the seismic intensity of the United States, Japan, China(including Mainland China and Taiwan region). Aiming at the situation of high record peak value, it usually appears high when the instrument intensity is estimated by the peak acceleration(PGA), peak velocity(PGV). In this paper, the effective peak acceleration(EPA) and effective peak velocity(EPV) are used to calculate the instrument intensity.In this paper, the instrument intensity distribution of the Chi-Chi earthquake in Taiwan in 1999 is calculated, which is consistent with the actual intensity distribution. The results of the two kinds of methods are compared and analyzed in this paper. The results showed that the intensity circle determined by EPV in high intensity area(VII ~ X area) is less than the range of intensity determined by PGV. Low intensity regions(IV ~ VI area) is roughly equal the corresponding area range determined by the PGV. The instrument intensity determined by EPA, EPV is equal to or less than the instrument intensity value determined by PGA, PGV. It shows that in some special circumstances this method can improve the tendency to a certain extent that the intensity is overrated. In this paper, the instrument intensity is calculated by some strong earthquake records of Wenchuan earthquake, which verify these results.In the absence of strong earthquake observation stations, the distribution of the intensity is assessed by the rupture length of the source. In this paper, we have collected and sorted out the parameters of the magnitude and rupture length of the 132 earthquake in China. The empirical formula between magnitude and rupture length is obtained by regression analysis, which can be used in the future. At the same time, the correlation of surface wave magnitude to the surface rupture length is higher than that of the moment magnitude. To determine the earthquake source rupture length, the moment magnitude has a higher correlation than the surface wave magnitude.