The Research Of GNSS Applied In The Seismic Moment Tensor Inversion

With the development of GNSS precision positioning, GPS observation data has been extensively used in quantitative seismology research. In that case, GPS provides a reliable method to the study of seismology, including the rupture of earthquake, the calculation of moment tensor, the focal mechanism and the best double couple. It has profound meaning in seismology research.The study discusses the theoretical algorithm to determine the moment tensor and centroid location for earthquakes employing displacement records from GPS. Besides, it introduces the methods to extract high quality coseismic offset from RENIX data. The inversion experiment in the study contains four large events:the El Mayor-Cucapah earthquake, the Lushan earthquake, the Tohoku-Oki earthquake and the Wenchuan earthquake. The detail information is summarized as follows:1. The principle and method of GPS information to invert for moment tensor are expounded, as well as the calculation of focal mechanism and the best couple solution.2. Briefly discusses the carrier phase data processing model of GAMIT. Illustrates the GAMIT batch process with El Mayor-Cucapah earthquake data treating. Introduces the processing method of trackRT module.3. Using the coseismic displacement of different sample rate GPS data solution for respectively earthquake inversion. The result turns out that 30Hz data can describe the deformation more exactly than the 1Hz high-rate data. Conducts the earthquake inversion employed with different distribution of GPS data, finding out the law on which GPS sites distribution influenced the inversion.4. Uses different models (half-space structure model and the layered model) to gain Green function and compares the two inversion results. The comparison shows no difference that the two models can replace each other. Uses Wenchuan earthquake and Tohoku-Oki earthquake as the representative of large events to verify that the strong motion is not the direct factor to affect the inversion result.In a word, by means of a lot of different experiment, the study summarizes the rule of four influence factors on the earthquake inversion and optimizes the inversion method.