Rapid Determination Of Earthquake Source Parameters Constrained By High-rate GNSS And Seismometry

Earthquake early warning refers to calculating earthquake source parameters rapidly and issuing early warning information before the disaster strikes.It's an important means to mitigate earthquake disasters at present.With the progress of GNSS and the enhancement of real-time calculation and transmission capability,real-time GNSS seismology has made great progress.Introducing GNSS technology into earthquake early warning system can complement the advantages of existing system and obtain earthquake source parameters more quickly and accurately,which is an important tendency of development in the future.This paper focuses on the algorithm of calculating epicenter,magnitude,intensity and rupture process based on GNSS and strong motion record.The effectiveness of the algorithm is analyzed by Wenchuan Earthquake and 3.11 Japan Earthquake.The main contents and conclusions of this paper are as follows:1.On the basis of previous studies,the method of STA/LTA and AIC are used to extract the arrival time of seismic waves,and the original time and epicenter location are inverted by combining station coordinates.The observational data are increasing continuously in actual applications.According to the least square principle,the evaluation index is put forward and the most reliable epicenter location is selected among all results.We collected and processed the GPS data of Wenchuan Earthquake and strong motion record of 3.11 Japan Earthquake.The epicenter algorithm has been validated.Compared with the authoritative results,the epicenter location deviations of two earthquakes are more than ten kilometers,which meets the accuracy requirements of earthquake early warning.2.Analogizing statistical relationships between strong motion records(PGA,PGV)and intensity,the relationships between GNSS(PGA,PGV,PGD)and intensity are established.We collect the strong motion records in Wenchuan Earthquake and simulating the timeseries of cosesimic displacement based on the characteristics of GNSS data.Statistical results show that the PGA,PGV and PGD in displacement data also have corresponding relations with intensity,and the statistical formulas are given.3.We processed the surface displacement time series of Wenchuan earthquake and 3.11Japan Earthquake,and the static displacement was extracted by a moving average window.Finally,we inverted the fault rupture process and moment magnitude timeseries of two earthquakes.The initial magnitude of the Wenchuan earthquake is Mw7.0 at 20s after the origin time,and the magnitude of the Wenchuan earthquake is stable at Mw7.8 at 70s after the origin time.As to the 3.11 Japan Earthquake,the initial magnitude was Mw7.6 at 42s and reached Mw8.9 at about 130s.Compared with the traditional earthquake early warning methods,the magnitude results are more accurate and efficient.4.Comparing the magnitude calculation methods of ?_c,PGD and inversion of fault slip distribution,the magnitude time series of 3.11 Japan Earthquake is given.The results show that the data of strong motion are more sensitive and have better timeliness.The magnitude obtained from GNSS data is more reliable.The two methods can complement each other.