Dynamic rupture propagation during the 1891 Nobi, central Japan, earthquake: A possible extension to the branched faults

摘要

The dynamic rupture process of the 1891 Nobi, Japan, earthquake was closely reinvestigated by using a boundary integral equation method based on currently available observations. We discussed mainly a possibility of the rupture propagation on branched faults, including a buried fault called the Gifu-Ichinomiya line. Several numerical simulations were made incorporating the information on the fault geometry based on the active fault traces on the ground surface and the maximum principal strain direction observed by the triangular surveys for the past 100 years. The results suggest that the rupture should propagate along the buried fault during the Nobi earthquake if a weak geological discontinuity exists along the Gifu- Ichinomiya line and is connected to the Neodani fault, which is one of the major surface faults appearing during the Nobi earthquake.