A Multi‐Segment Analytic Modeling of Hypocentral Geometric Characteristic Parameters of the Ms8.1 Earthquake at the Kunlun Mountains

Abstract

AbstractPrevious studies about the Kunlun Mountains Ms8.1 earthquake have a lot of differences in its hypocentral characteristic parameters such as the rupture length, direction of rupture plane (discontinuity plane), and the size of the rupture plane. First, utilizing the D‐InSAR technology we obtain the coseismic displacement field of the Kunlun Mountains Ms8.1 earthquake. Combining the field investigation, along the main rupture zone the displacement in the satellite line of sight (LOS) is decomposed. Synthesizing the results of InSAR interferogram, field investigation and satellite image interpretation, the rupture zone of the earthquake is re‐divided into segments. Meanwhile, a set of geometric parameters of the rupture are obtained. Second, analyzing the strain of north‐south walls of the fault, we find an asymmetric displacement distribution between the two sides of the rupture, and both of the walls are acted by compressive and tensile stress, respectively, a pattern that cannot be explained with the linear elastic theory. 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, for simulating the earthquake displacement field, we present a model of multi‐hypocenter, heterogenous dislocation, and multi‐rupture section superposition. The simulated LOS interferogram by the model exhibits a more complete distribution characteristics of the earthquake displacement field than that of previous work. It provides a better explanation to the hypocentral characteristic parameters of the geometry, size of dislocation for a large surface rupture field, and the non‐homogeneity of coseismic dislocation.