The Inversion Of Fault Locking And Fault Slip Deficit Of The Red River Fault Zone By GNSS Data

The Red River fault zone is located in Yunnan Province on the southeast edge of the Qinghai Tibet Plateau,which is the southwest boundary of Sichuan-Yunnan rhombic block,and the boundary fault between the Yangtze block and the Indochina block.There are strong piate movement on both side,extremely complex tectonic background and frequent seismic activities on The Red River fault zone,which makes it become a window and hot area of plate movement and seismological research.In this paper,based on studying the principle of the theory of negative dislocation,we make the model is further refined.And we use the GNSS velocity fields of 1999-2007 and 2009-2013,and the negative dislocation-block model of TDEFNODE to invert fault locking and fault slip deficit of the Red River fault zone.The results show that before 2008,the average strike-slip rate and dip-slip rate of the Red River fault zone is 3.8±2.5 mm/a and 1.2±2.5 mm/a,the northern and middle segments exhibit tension,and the southern segment exhibits compression.The locking fraction of the northern and middle segments between depth 0 to 15 km is between 0.8and 0.99,and the slip deficit rate of the northern and middle segments is 4.5 mm/a,which is easy to accumulate strain energy quickly.The locking fraction of the southern segment between depth 0 to 10 km is between 0.8 and 0.95,and the fault slip deficit rate of the southern and middle segments is 4.5 mm/a.After 2008,the fault locking and fault slip deficit rate in the middle segment have decreased,and the fault locking and fault slip deficit rate in the southern segment have increased.Besides,we think that the impact of Wenchuan earthquake on the Red River fault zone is small.The Red River fault zone is deserved further study.It is hoped that above studying can provide for the seismic risk assessment of the Red River fault zone.