Investigation of earthquake jump distance for strike-slip step overs based on 3-D dynamic rupture simulations in an elastic half-space

Abstract

We systematically investigate the distance that dynamically propagating earthquake ruptures could jump across step overs in strike-slip faults set in a homogeneous half-space. The following factors are found to have major effects on the critical jump distance: the dimensionless effective shear stress, the initial normal stress, the Earth's free surface, and the accelerating length of the rupture front on the main fault prior to a jump. An important finding in this study is that the critical jump distance for extensional step overs could exceed 10 km under certain conditions, while ruptures on compressional step overs under the same conditions could only jump 6 km fault step overs. This may provide a physical explanation for some geological observations of over 10 km jump distance in natural earthquake. The critical jump distance usually increases as the dimensionless effective shear stress increases. Without the free surface effect, the critical jump distance for step overs could only reach up to 6 km, which is very close to the 5 km given by the classic 2-D simulations.