FINITE ELEMENT ANALYSIS OF SLIP PARTITIONINGS ON ACTIVE FAULTS: DETECTING OCCURRENCE CONDITIONS FOR A COMBINATION OF REVERSE AND STRIKE-SLIP FAULTS

Slip partitioning on active faults is an infrequent slip pattern since the phenomenon always requires two fault planes placing close to each other: one for the normal/reverse fault, the other for the strike-slip fault. However, investigating the slip partitioning is important in the earthquake hazard assessment because the slip partitioning probably occurred during the 2016 Kumamoto earthquake. This paper investigates the occurrence conditions for the slip partitioning using finite element analysis with several parameters such as the fault dip angles and the compression direction of tectonic stress. On the bases of the results for 784 case studies, the following outcomes were found: (1) the simulation results derived a parameter set that highly activates slip partitionings, (2) the simulation results revealed the sensitivity of the parameters to the slip partitioning, and (3) the ratios, which are produced by the strike-slip and the reverse-slip magnitudes, mostly converge into a range between 0.8 and 0.9 with the higher values of the intensity for slip partitionings.