Application Of High-rate GNSS Precise Positioning Method In Seismic Element Inversion

Every year,thousands of earthquakes erupt around the world,with devastating effects on humans,such as the Wenchuan 5·12 earthquake and the Japan 3·11 earthquake,etc.All of which have caused great damage to human society,seismology has always been an important part of scientific and technological worker's research hotspots.For a long time,GNSS technology has been used as a primary monitoring tool for obtaining information on crustal deformation.In recent years,with the rapid development of GNSS technology and the establishment of continuous high-rate GNSS monitoring stations in various countries,the scope and extent of its application research has been continuously deepened.The high-rate GNSS positioning technology has been used to obtain instantaneous crustal deformation information during earthquakes and to obtain GNSS displacement signals.The acquisition of seismic wave signal information based on GNSS displacement signals,and then the inversion of seismic-related elements has become One of the popular research topics in GNSS seismology.Traditionally,seismographs are used to obtain instantaneous crustal deformation information,but it has certain limitations,and high-rate GNSS positioning technology has many advantages in acquiring seismic transient crustal deformation information,such as:no integration,no amplitude and Gravity field limitation,etc.Therefore,performing high-precision positioning calculation on high-rate GNSS observation data and obtaining reliable instantaneous crustal deformation information are prerequisites for inversion of seismic-related elements.However,there are still many problems in the application research of high-rate GNSS positioning technology in earthquakes,such as:1)the accuracy of dynamic positioning results is no sufficient to analyze centimeter-level deformation;2)the solved displacement deformation results are difficult to obtain accurate seismic signal information.This article focuses on the above two issues.The main research work and conclusions of this article are as follows:(1)Analyze three commonly used precision dynamic positioning methods,select the PPP method suitable for this article,use the PPP module of PANDA software to solve high-frequency GNSS data,and summarize a set of high-rate GNSS based on the characteristics of PANDA software and high-rate data processing data precision processing strategy to determine the functions of the system combination,precision ephemeris products,precision clock difference products,parameter configuration and tropospheric projection used in this article.(2)Perform stellar day filtering on the high-rate GNSS dynamic positioning results,and then use the improved S-transform method to further denoise the filtered results.Through an example analysis,the improved S-transform has better denoising effect than the S-transform,which can acquire the seismic wave arrival signal more accurately.According to the characteristics of the acquired high-rate GNSS displacement signal and seismic wave signal,the improved S-transform combined with the trend term denoising method was used to denoise the GNSS displacement signal,and the implementation process of the method is given.The results prove that the method is more accurate extracting seismic wave signal information,but it also has certain limitations.(3)The application of high-frequency GNSS precision positioning method in seismic element inversion.By filtering and denoising the resolved dynamic positioning results of each GNSS observation station to reduce the GNSS displacement signal noise,and the time when the seismic wave arrives at each GNSS observation station is obtained.the mathematical model of earthquake epicenter inversion and its program implementation are established based on the high-frequency GNSS data,and the model is used to invert the earthquake epicenter location and epicenter moment and other related elements.Using high-rate data during the Chile earthquake,Wenchuan earthquake and the 311 earthquake in Japan to processing and analysis,the inversion time of the Chile earthquake is 4 seconds away from the time announced by the US Geological Survey and the location of the epicenter is different from the position announced by the US Geological Survey 27.4km;the inversion time of the Wenchuan earthquake inversion is 6 seconds different from the time released by the China Earthquake Administration and 3 seconds from the time announced by the US Geological Survey(USGS),and the epicenter position is 12.5km away from the epicenter position announced by the China Earthquake Administration;The earthquake time of the Japan 311 Earthquake Reversal differed from the time announced by the Japanese GEO organization by 3 seconds,and the location of the epicenter was 26.1km from the position announced by the Japanese GEO organization.The inversion results of the three earthquake example elements are comparable to the results published by various international earthquake organizations.The error at the time of occurrence is on the order of seconds,and the error in the location of the epicenter is about 20 kilometers,the more uniform the station distribution,the higher the inversion accuracy.