A multi-segment analytic modeling of hypocentral geometric characteristic parameters of the M_S8.1 earthquake at the Kunlun Mountains
MA Chao 1,2, SHAN Xin-Jian11 State Key Laboratory of Earthquake Dynamics, Institute of Geology, China Earthquake Administration, Beijing 100029, China2 Taiyuan University of Technology, Taiyuan 030024, China
We make a further study on the hypocentral parameters such as the length and width, the direction and the size of the rupture of the M_S8.1 earthquake at the Kunlun mountains. First, using D-InSAR technology, the co-seismic deformation field of the earthquake is obtained for the first time. Combining the field investigation data, along the main rupture zone the displacement in the satellite line of sight (LOS) is decomposed. Synthesizing the results of InSAR, field investigation and interruption by remote sensing images, the sub-rupture zone of the earthquake is mented again. Second, by analyzing the strain of north-south blocks of the fault, we find an asymmetric displacement distribution between the two sides of the rupture, and the two blocks are subject to compressional and tensional stress respectively. It is a pattern that cannot be explained with the linear elastic theory. However, laboratory experiments and in situ measurements in boreholes have shown that many crustal rocks exhibit a nonlinear elastic behavior in compression and tension with a dependence of the Young's modulus on the minimum principal stress. So we suggest that the nonlinear displacement distribution should be considered when dislocation and hypocentral parameters are analyzed. Finally, we present an arithmetic of multiple-hypocentral, heterogenous dislocation, and a multi-rupture segment superposition model for simulating the earthquake deformation field. The simulated LOS interferometry map presents the distribution characteristics of the earthquake deformation field better than that of previous studied. Meanwhile, a suit of fault geometric parameters of the earthquake is also obtained by the study. Having a better effect upon simulating asymmetry, great dislocation, macro rupture field, and non-homogeneity of dislocation than the traditional model, the multi-segment method is a progress of this work. It provides a better explanation for the study on hypocentral parameters.