GNSS coordinate anomaly analysis before and after volcanic seismic activity based on ESMD method
Volcanic seismic activity has a great influence on the location of ground observation stations. In order to explore the displacement of global navigation satellite system (GNSS) observation stations before and after volcanic earthquakes, this paper took Tonga's volcanic seismic events as an example. Based on the observation data of Tonga (TONG) Station for two months, PRIDE-PPP-AR software was used to solve the data. The extreme-point symmetric mode decomposition (ESMD) was introduced to decompose the coordinate time series and analyze the coordinate displacement. The results show that the accuracy of the data solution is high, and the error in the north (N) and east (E) directions is about 5 mm. The accuracy in the vertical (U) direction is about 9 mm. On the day of the earthquake and 1-2 days before the earthquake, there was an obvious disturbance in the coordinates in the E direction, which deviated from the normal value by about 0.1 m. On the day of the earthquake, the coordinate time series in the U direction had insignificant anomalies, but a significant disturbance of the coordinates could be observed 1-2 days before the earthquake. Through the ESMD method, it could be observed that the signal amplitudes of Model 1 and Model 2 in the GNSS coordinate time series in the E direction had obvious abnormal disturbances before and after the earthquake, and there were obvious coseismic disturbances. The signals of Model 1-Model 3 in the U direction had obvious abnormal disturbances of coseismic amplitudes. The abnormal disturbance of the coordinates in the N direction was not obvious. From the perspective of the total energy signal, multiple prominent energy anomalies could be observed in the U and E directions, and the intensity of the anomaly was 3-10 times the normal level. Some coseismic and preseismic energy anomalies could also be found in the N direction, but they were not obvious.
万方数据
维普
