Statistical Analysis of Noise in GPS Time Series of Sichuan Province Before and After the 2008 Wenchuan Earthquake

In order to explore the long-term influence of seismic events on the GPS time series, 10 a long processing results of the Sichuan GPS network before and after the 2008 Wenchuan M8.0 earthquake were used for the multi-parameter noise model analysis. Based on the maximum likelihood estimator method and spectrum analysis, the noise components in the station coordinate time series were extracted. Through Λ-statistical tests, we found ‘white noise+ flicker noise’ is the best combination that can best fit the Sichuan local area network. Meanwhile, it is noted that apparent variations in the noise component of GPS, including white noise, flicker noise, and random walk nose, occurred before and after the seismic event, which demonstrates that the traditional processing mode which simply splices and resolves the pre-seismic and post-seismic data together is unacceptable. The common mode error analytical method and velocity variation information were used for the initial physical interpretation of such apparent noise component change.