Study On The Dynamic Change Of The Poisson's Ratio Of Surrounding Stations Before And After The Jinggu M6.6 Earthquake In 2014

On October 7,2014,the M6.6 earthquake occurred in Jinggu,Dai and Yi Autonomous County,Pu'er City,Yunnan Province.The epicenter was located in Yongping Town,Jinggu County(23.4 °N,100.5 °E),with a focal depth of 5.0 km.In this paper,the method of obtaining the Poisson's ratio of the crustal medium by using the time-lapse information of the teleseismic P-wave receiver function Ps converted wave and multiple converted waves PpPs seismic phase,combining with moving average analysis method,obtained the depth of Moho and the average Poisson's ratio distribution in Yunnan and surrounding areas,analyzed the variation characteristics of the crustal medium Poisson's ratio of 10 fixed seismic stations within 200 km of the epicenter of Jinggu M6.6 earthquake,and got the following recognition:1.As a whole,the depth of the Moho surface in the Yunnan area presents the characteristics of "deep in the north and shallow in the south",showing a tongue shape along the SSE direction.Most earthquakes with magnitude 6 or higher in the study area occurred in areas with high Poisson's ratio or high gradient zone,and Jinggu earthquake occurred in areas with high Poisson's ratio.2.Before the Jinggu M6.6 earthquake,the two stations with the epicentral distance<65km,that is,the two stations closest to the epicenter,showed obvious and consistent low-value anomalies in the Poisson's ratio of the crustal medium.The low-value anomalies lasted for a long time and changed shape and the characteristics are in "V" or double "V" shape,while the remaining stations show random changes.3.A comprehensive observation of the stations where the Poisson's ratio has changed reveals that as the epicentral distance increases,the decrease in the Poisson's ratio gradually becomes insignificant,the occurrence time of the low value is gradually delayed,and the duration of the low value also increases As the epicentral distance increases,it decreases.4.Combining the decrease of Poisson's ratio before the earthquake and its spatiotemporal characteristics,post-earthquake changes,occurrence time and the number of stations with these changes,the overall analysis suggests that the teleseismic P-wavereception function can be applied to areas with high enough network density.Dynamically monitor the change of the Poisson's ratio of the crustal medium and obtain important indications of the changes in the properties of the crustal medium before the earthquake to explore scientific methods for predicting and predicting earthquakes.