Calculation Of The Crustal Thickness And Poisson's Ratio Of Yunnan Using The Frequency-domain Receiver Functions Of Multiple Seismic Events

In this paper,I use the self-made program of Receiver functions in the frequency domain to calculate the crustal thickness and Poisson's ratio in Yunnan.Four teleseismic events are chosen,including a Ms 7.6 earthquake in Solomon Islands in April,12,2014,a Ms 6.7 earthquake under the sea near Solomon Islands in August,10,2015,a Ms 6.4 in Greece in Feb.3,2014,and lastly a Ms.7.1 earthquake in Alaska in Jan.24,2016.From the calculated P receiver functions at 46 digital seismic stations deployed in Yunnan,I identify the Ps and PpPs phases,from the arrival times of which the crustal thickness and Poisson's ration are accurately computed.Finally,I analyze the results against the geological background in this region.The results show that the crustal thickness of Yunnan is between 30?5 5km,"North thick South thin",from the north by around 55km(Zhongdian station)gradually reduced to the south around 30km(Mengla station);Poisson's ratio of crustal is between 0.20?0.35,distribution is uneven,and block of distribution,the Poisson's ratio in Tengchong area is highest,up to 0.327,and the crustal Poisson of Dongchuan,Simao and Chuxiong etc stations are relatively high,the lowest value appears in the Jinggu area,only about 0.221;the deep fault has obvious boundary effect,the Honghe Fault,Xiaojiang fault and Lijiang-Xiaojinghe Fault enclose an area with very thick crust and high Poisson' ratio,indicating that the southeastward crustal flow from Tibet Plateau has arrived at the Lijiang-Xiaojinghe Fault and is being resisted by this fault;On the right side of the Honghe fault,the Moho interface is deeper than that on the left side,showing that the fault is the west boundary of the Sichuang-Yunnan Diamond Block;The TengChong Volcanic Area is distributed by high Poisson's ratio and shallow crust;The high Poisson's ratio in Simao is associated with the possible small volcano there;Dongchuang has a high Poisson's ratio,well corresponding to its location at the Xiaojiang fault,being underlain by fractured crust.Both crustal thickness and Poisson's ratio yielding from the four(above)events have small standard deviations and high correlation coefficients.Moreover,the seismological results are surprisingly consistent with the geological evidence in Yunnan.It is concluded that the calculated receiver functions and phase recognition procedures are robust.In order to study the geological features and dynamic models of Yunnan,we provide a relatively complete,accurate and reliable geophysical variable distribution image.