Abstract:We propose a comprehensive prediction index method based on the measurement of ambient noise wave velocity to better apply the seismic data to earthquake situation tracking and short-term and imminent earthquake prediction. Using broadband continuous waveform data from January 2012 to November 2020 recorded at 5 stations in northwestern Yunnan, based on ambient noise cross-correlation and Fourier transform methods, we extract the direct Rayleigh wave travel time offset time series of day empirical Green’s function and reference empirical Green’s function of 10 station pairs. We set ±1.5 times the standard deviation as the anomaly threshold, take 6 earthquakes with M≥5.0 as samples, and use the R value scoring method to test earthquake capability of each station pair. Finally, based on the adaptive weighted comprehensive prediction method, we extract the short-term and imminent earthquake anomaly identification index(comprehensive index) suitable for northwestern Yunnan. The results show that when the comprehensive index is used for 90-day short-term and imminent prediction of 6 earthquakes with M≥5.0 occurring in northwestern Yunnan since 2012, a total of 8 abnormal indicators have occurred, of which 5 earthquakes are accurately predicted, 1 missed report, and 4 false reports. The predictive performance score R is 0.692, R0 is 0.475. The earthquake response rate of this comprehensive index is 62.50%, and the generalization rate is 83.33%.
YANG Jianwen,YE Beng,GAO Qiong et al. Study on the Relationship between Wave Velocity Anomalies and M≥5.0 Earthquakes in Northwestern Yunnan Using Ambient Noise[J]. jgg, 2022, 42(2): 165-171.