19 Lantmäteriet-the Swedish mapping, cadastral and land registration, Sweden

Based on GPS observation between 1991 and 1999 in Sichuan and Yunnan, we adopt the robust Baye's least squares estimation and multi‐fault dislocation models to analyze the quantitative kinematics models of the main boundaries of the rhombus block in Sichuan and Yunnan. The geodetic inversion suggests that the left‐lateral strike slip rates of the Xianshuihe fault zone and the Anninghe fault zone in Sichuan are about 30mm/a with overthrust faulting at rates of roughly 9 and 11mm/a respectively; in Yunnan, the right‐lateral strike slip rate of the Red River (Honghe) fault zone is 10mm/a with a normal faulting of 16 mm/a; and the left‐lateral strike slip rates of the Chenghai fault zone and the Heqing‐Eryuan fault zone are about 11 and 13 mm/a with normal faulting at rates of about 24 and 16mm/a separately. If all displacements along these faults were accommodated by elastic stress and strain, thus the accumulated seismic energy on each fault would be sufficient to produce a moderate earthquake with Ms ~6 each year. According to above results, the horizontal displacement and strain field caused by the main fault movement were simulated and showed the interaction among boundary faults.

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The 4.20 Lushan M S 7.0 earthquake occurred on the southwest segment of the Longmenshan fault on 20 April 2013. Some meaningful information on the preparation and occurrence of this earthquake was found based on the dynamic variation of gravity (DVG). To examine the great progress of the Lushan earthquake, we obtained the density variation (DENV) derived from the DVG using the compact gravity inversion method in this article. The inversion results reveal three main findings: (1)