Application Of Scaling-rule Theory In Crustal Rock Fracture To Studying Characteristics Of Seismological Precursors Associated With Earthquakes Occurred In Gansu Province Recent Years

In 1980, on the Bases of fractal theory,Allegre, a France scientist, studied the scaling-rule theory of crusral rock using the technique of renormalization group and pointed out that it can be applied to earthquake prediction. According to Allegre's theory, the two seismological precursors have been studied: Q -Value of coda and the spatial correlation length of earthquakes, which reflect physical characters of crustal rock in different scale. The systemic exposition of studying history, calculating principle and method have been made. The two models to calculate coda Q - values (Aki and Sato model) have been analyzed contrastively. The Aki model and single-link cluster method are used to calculate the coda Q -values and the seismic spatial correlation length respectively. As examples of earthquake the precursor characteristics of two seismological parameters (coda Q -value and seismic spatial correlation length ) before two great-moderate earthquakes and a earthquake swarm (Shandan-Minle earthquake, M =6.1, Oct. 25, 2003; Minxian earthquake, M =5.5, Nov. 13, 2003 and Linze swarm, June, 2004) have been studied and their changing courses with time have been obtained. The results show an increasing trend of seismic spatial correlation length and coda Qc before the two earthquakes and a power exponent relation is used to fit the increasing variation form of these two parameters. The result for Linze swarm does not show the same increasing variation form as the two earthquakes. The studies have provided a basis for creating a method and finding indexes to predict the earthquake occurrence time by using the monitored seismic spatial correlation length and coda Qc.