On July 31th, 2016, a magnitude 5.4 earthquake struck Cangwu Country, Guangxi Zhuang Autonomous Region, it was the largest earthquake recorded by Guangxi Seismological Network since it set up. The number of people affected by the earthquake had reached 20 000, and the direct economic losses caused by the earthquake were nearly 100 million Yuan.
After the earthquake, USGS provided a global earthquake catalog showing that the focal depth of Cangwu earthquake was about 24.5km. However, the result given by the Global Centroid Moment Tensor showed the focal depth of this earthquake was 15.6km. However, the result obtained by Xu Xiaofeng et al. using CAP method was 5.1km. It was clear that the focal depths of Cangwu earthquake given by different institutions were quite different from each other. However, accurate focal depth of the earthquake has important significance for exploring the tectonic mechanism near the epicenter, so it is necessary to further determine the more accurate depth of the Cangwu earthquake.
In order to further accurately determine the focal depth of Cangwu earthquake, we used the global search method for travel-time residual to calculate the focal depth of this earthquake and its error range, based on the regional velocity model, which is a one-dimensional velocity model of the Xianggui tectonic belt produced by the comprehensive geophysical profile. Then, we inverted the focal mechanism of this earthquake with the CAP method. Based on this, the focal depth of Cangwu M_S5.4 earthquake was further determined by the method of the Rayleigh surface wave amplitude spectrum and the sPL phase, respectively.
Computed results reveal that the focal depth of this earthquake and its error range from the travel-time residual global search method is about(13±3)km, the focal depth inverted by CAP method is about 10km, the focal depth from sPL phase is about 10km, and the focal depth from Rayleigh surface wave amplitude spectrum is about 9~10km. Finally, we confirmed that the focal depth of Cangwu M_S5.4 earthquake is about 10km, which indicates that this earthquake still occurred in the upper crust. In the case of low network density, the sPL phase and Rayleigh wave amplitude spectrum recorded by only 1 or 2 broadband stations could be used to obtain more accurate focal depth.
The focal depth's accuracy of Cangwu M_S5.4 earthquake in the USGS global earthquake catalog has yet to be improved. In the future, we should consider the error of the source parameters when using the USGS global earthquake catalog for other related research.

In this paper,we calculate receiver functions of body wave under the 18 stations in Anhui Province from 3-component digital waveform data of teleseismic earthquake events and obtain the thickness and V_P/V_S ratio in the crust of this area through H-Kappa stacking. Our result is consistent with previous studies. Combining the tectonics data and our result,we consider that Anhui area can be divided into three areas according to the crustal thickness. The first one is the Dabie Shan area in the southwest of Anhui Province,the crustal thickness is about 35 to 38km; the second one is the southeast of Anhui Province,the crustal thickness is about 34km; and the last one is middle and northeast of Anhui,the crustal thickness is about 31 to 32km. The V_P/V_S ratio in Anhui area does not vary obviously spatially,but there are three stations LAN,SCH and JSA,under which the crustal velocity ratio is obviously higher,up to 1.79,1.80 and 1.80,respectively. In fact,the station LAN and SCH are located at the border between the North China block and the Yangtze block,and the JSA station is on the Tan-Lu Fault zone and beside the Sulu UHP metamorphic belt. Therefore,we infer that the high crustal velocity ratio under LAN,SCH and JSA stations are probably attributable to the deep large faults beneath the stations.

Based on teleseimic data for the period of 2007 to 2010 acquired from the Three Gorges reservoir(Chongqing section)seismic network and Chongqing regional seismic network,we obtained the crustal thickness and Possion's ratio of the area through receiver function method.The results show that the crustal thickness ranges from 38.9km to 50.9km.Station CHK in northeastern Chongqing has the largest thickness which is about 50.9km;the thinnest crust is 38.9km under the station ROC in the west of Chongqing,and Poisson's ratio is about 0.27.The results show that the maximum Posson's ratio is beneath station JIZ in the east of the Chongqing section of Three Gorges Reservoir area,and the minimum Possion's ratio is beneath the station WUL,which is 0.228.In comparison with the Poisson medium(0.25),its maximum deviates up to 20.8%,and the minimum deviates by-8.80%.The Bouguer gravity anomaly often reflects subsurface density and crustal thickness variation.In this paper,the two agree with each other.The largest negative Bouguer anomaly is between CHK(50.9km)and WUX(49.7km),where the crust is the thickest.The smallest negative Bouguer anomaly is between ROC(38.9km)and YUM(41km),where the crust is the thinnest.

Songhuajiang-Liaohe Basin is surrounded by several folded mountains,with some major deep faults running across them.Among these faults,the Tanlu Fault is one of biggest active faults in the east China continent.This kind of geological environment makes Liaoning and its adjacent areas be capable of highly active tectonic movement and high seismicity.As crustal thickness and Poisson ratio are closely related to seismogenic structure,studying on these parameters will be very important for us to understand the seismogenic process of Liaoning and its neighboring regions.In this work,teleseismic P wave records from 15 permanent broadband seismic stations in Liaoning province are collected and processed by inverse convolution method in spectral domain to get the P wave receiver functions.The H-Kappa stacking method is further used to obtain the crustal thickness and Poisson ratio under each seismic station.The result shows that Poisson ratio in this region is between 0.25and 0.29,and crustal thickness ranges from 31km to 36km.Comparing with the Harbin Basin,the crustal thickness of the west and east fold belts in this region is about 2～4km thicker.The distribution pattern of crust thickness shows that the crust is getting thicker from east to west and from north to south,with an average crustal thickness about 31km in Songliao Basin.This pattern shows that the Songhuajiang-Liaohe Basin is a typical rift basin,its seismogenic process may mainly be controlled by the subsidence of the basin and the horizontal extension from the east and the west boundaries.

In this paper,we calculate receiver functions of body wave under the 14 stations in Shaanxi Province from 3-component digital waveform data of teleseismic earthquake events and obtain the thickness and Poisson ratio in crust of this area through H-kappa stacking.Through analysing the characteristics of crustal structure in Shaanxi Province,we discuss the relationship between seismic activity,crustal structure and geological structure in Shaanxi Province.The results show that(1)Crustal thickness in western Shaanxi is thicker than that in the east.Crustal thickness in the south and north of Shaanxi(≥40km)is larger than that in Weihe Basin,middle Shaanxi(about 34～40km).Among 14 stations,the crust beneath Huayin station is the thinnest(34km),which locates on the boundary between eastern Weihe Basin and Shanxi Province,and the biggest thickness(48km)appears beneath Longxian station at the northwestern end of Weihe Basin.(2)Poisson ratio in Shaanxi Province is about 0.24～0.29,which may be related to rock compositions.Poisson ratio in the north of Weihe Basin has higher values than those in the south.(3)There exist some relations between seismic activity and geological structure.The Weihe Basin with frequent earthquakes locates in a compound position of several tectonic systems.The Hanzhong Basin and Ankang Basin in the south of Shaanxi are controlled by several major faults,where the seismicity is relatively low.Seismic activity in northern Shaanxi is the lowest because of stable geological structure.Poisson ratio reflects material composition of earth interior.Our analysis suggests that seismic activity in the region with high Poisson ratio is higher than that with low Poisson ratio.