STUDY ON ANOMALY DATA VARIATION CHARACTERISTICS BEFORE TAJIKISTAN MS7.2 EARTHQUAKE ON FEBRUARY 23,2023 BASED ON GNSS
In order to further explore whether there are short-term and medium-term anomalies in the GNSS coordinate time series before the occurrence of moderate earthquakes,the variation character-istics of the observation data of GNSS reference stations in Tashkurgan and Bulunkou of China main-land tectonic environment monitoring network before Tajikistan MS7.2 earthquake on February 23,2023 are analyzed.It is found that there are obvious time series anomalies of GNSS reference sta-tions in Tashkurgan and Bulunkou before the earthquake.Before the earthquake,there is a trend of W-direction movement in EW direction.After the earthquake,the E-direction accelerates,and the NS-trending S-direction movement before the earthquake.The state changes rapidly before the earth-quake.After the earthquake,Bulunkou also shows a permanent deformation of 7.3 mm in EW di-rection.The results show that GNSS has important predictive significance in the short-term and im-minent stage of earthquake.Compared with in Tajikistan MS7.4 earthquake on December 7,2015,it is found that the influence of two earthquakes with magnitude greater than 7 on the base stations of Tashkurgan and Bulunkou is quite different.On December 7,2015,Tajikistan Ms7.4 earthquake was left-lateral strike-slip,and the direction of influence was mainly NE.On February 23,2023,Tajikistan MS7.2 earthquake was right-lateral strike-slip,and the direction of influence was mainly SE.The baseline before the earthquake showed all the precursory anomalies.By combing the anom-aly occurrence of the site,it is found that the longer the anomaly duration and the more the number of anomaly occurrences,the greater the magnitude of the earthquake may be.
NETL
NSTL
万方数据
