Interseismic slip distribution and locking characteristics of the mid-southern segment of the Tanlu fault zone

Abstract

In this paper, we employ the block negative dislocation model to invert the distribution of fault coupling and slip rate deficit on the different segments of the Tanlu fault zone, according to the GPS horizontal velocity field from 1991 to 2007 (the first phase) and 2013 to 2018 (the second phase). By comparing the deformation characteristics results, we discuss the relationship between the deformation characteristics with the 3.11 earthquake in Japan. The results showed that the fault couping rate of the northern section of Tancheng in the second phase reduces compared with that in the first phase, but the results of the two phases showed that the northern section of Juxian still has high coupling rate, the deep blocking depth, and the dextral compressive deficit, which is the unrupture section of the 1668 Tancheng earthquake. At the same time, the area strain results show that the strain rate of the central and eastern regions of the second phase is obviously enhanced compared with that of the first phase. The occurrence of the great earthquake in Japan has played a certain role in alleviating the strain accumulation in the middle and south section of the Tanlu fault zone. The results of the maximum shear strain show that the shear strain in the middle section of Tanlu fault zone in the second phase is weaker than that in the first phase, and the maximum shear strain in the southern section is stronger than that in the first phase. The fault coupling coefficient of the south Sihong to Jiashan section is high, and it is also the unruptured section of historical earthquakes. At the same time, small earthquakes in this area are not active and easy to accumulate stress, so the future earthquake risk deserves attention.