Mechanism on Moho offset induced by aseismic slip of deeply buried faults

摘要

Recent high-resolution deep seismic reflection profile across the Kunlun fault in northeastern Tibet shows clearly that the Moho is cut off by a complex thrust fault system.Moho offset is a general phenomenon,but little is known about the dynamic mechanism.In this study,contact models with Maxwell materials are used to simulate the mechanical process of Moho offset induced by the aseismic slip of deeply buried faults.Based on the seismic reflection data,we project a single fault model and a complex fault system model with two faults intersecting.The deformations of the Moho,the aseismic slips,and contact stresses on faults in different models are discussed in detail.Results show that the Moho offset might be produced by aseismic slip of deeply buried faults,and the magnitude is influenced by the friction coefficient of faults and the viscosity of the lower crust.The maximum slip occurs near the Moho on the single fault or at the crossing point of two intersecting faults system.Stress concentrates mainly on the Moho,the deep end of faults,or the crossing point.This study will throw light on understanding the mechanism of Moho offset and aseismic slip of deeply buried faults.The results of complex fault system with two faults intersecting are also useful to understand the shallow intersecting faults that may cause earthquakes.