Seismogenic-Induced Softening of the Earth Crust

The decade-long monitoring of the stress-strain state of the earth’s crust within the framework of the Southern California geomechanical model has enabled us to reveal an anomalous zone of softening of middle and upper crustal rocks. Softening occurs in the area of the Sierra Madre fault zone, located subparallel to the San Andreas fault to the south of the latter, as a result of oppositely directed displacements of the fault sides, leading to local softening of the fault area. Numerical characteristics of the anomalous zone are given, and a brief theoretical description is presented.