Depth distribution of lithospheric strength determined by the self-unbalancing shear rupture mechanism

摘要

It is generally accepted that the frictional strength of pre-existing faults represents a lower limit on rock shear strength in the seismogenic layer. The paper proposes an alternative concept based on a recently identified shear rupture mechanism (fan-mechanism). The fan-mechanism creates paradoxical effect providing the formation of new faults in intact rock mass at shear stress levels significantly below the frictional strength. This indicates that the lower limit of lithospheric strength is not restricted by the frictional strength. The varying efficiency of this mechanism with depth provides a specific depth distribution of lithospheric strength.