High-rate GNSS Data Processing And Application Of Earthquake Early Warning

Since built,the Global Navigation Satellite System(GNSS)has made a considerable progress and development,and the scope of its applications in various aspects of human life is more widely.In recent years,with the appearance and popularity of high-rate(1~50Hz)GNSS receiver and mature dynamic resolving methods,the high-rate GNSS observation techniques play an increasingly important role in monitoring strong ground motions,such as earthquakes,tsunamis,etc.This article describes the background,research status and development prospects of the use of high-rate GNSS technology for seismic analysis.It elaborates some basic concepts,composition and observing principles etc,related to global navigation satellite system,and the sources of errors that effect GNSS observation.It introduces the common high-frequency GNSS solution method: Precise Point Positioning PPP and so on.Then I use the 1Hz GNSS data from IGS stations as MIZU,USUD,DAEJ and JA01 of GEONET in Japan to calculate the 2011 Mw9.0 earthquake waveforms in Tohoku-oki,Japan,and those from domestic PIXI,QLAI,CHDU,ZHJI stations to calculate the 2008 Mw7.9 earthquake waveforms in Wenchuan,China.Then those displacement time series are applied to analyze their waveforms,identity the seismic phases and inverse the three elements of earthquakes.After summing up the traditional seismology method to pick up the seismic phases: the STA / LTA method,and the wavelet transform method.After the first order difference,the long-term signal trends of the high-rate GNSS data are elimilated.The S transform method is used to identify the GNSS seismic phases of the earthquakes happened in both Japan and Wenchuan,and pick up the arriving time of the seismic waves.I use the pick-up results from some stations to inverse the location of the epicenter and origin time of the event,and then apply the permanent deformation of coseismic displacement to calculate the moment magnitude of the two strong earthquakes.At last,three elements of the earthquakes obtained above are compared with the final results published by the US Geological Survey(USGS).Via the inversion,I get the epicenter location of the earthquake in Japan as ,16 km away from and USGS published;the origin time difference is 0.748 s,as 5: 46: 24.748(UTC);calculate the moment magnitude as Mw8.8876,about 0.2 units below Mw9.0,the USGS released.Meanwhile,I obtain the epicenter location of the earthquake in Wenchuan as,3.96 km away from and USGS published;origin time difference is 0.41 s,as 6: 28: 01.41(UTC);calculate the moment magnitude as Mw7.74,also about 0.2 units below Mw7.9,the USGS released.