Study on Seismic Precursory Anomaly Signals Based on Critical Slowing Phenomena

Abstract

This paper applied the principle of critical slowing down to the processing of radon concentartions observation data, calculated the autocorrelation coefficient and variance which can characterize critical slowing down by taking Wenchuan Ms8.0 earthquake on May 12, 2008, Lushan Ms7.0 earthquake on April 20, 2013, Minxian-Zhangxian Ms6.6 earthquake on July 22, 2013, Jiuzhaigou Ms7.0 earthquake on August 8, 2017 as examples. The result indicated that the water radon concentration at several stations has obvious critical slowing phenomenon before server earthquakes. The formation mechanism of radon concentration anomalies in seismic underground fluids was discussed in the context of the focal mechanism solution of several earthquakes. It is considered that the phenomenon of critical slowing down before server earthquakes is related to the earthquakes occurrenced combined with the hydrodynamic mechanism of radon anomaly and the structure of the abnormal points.