Abstract
A series of 3-D FDM simulations are demonstrated for studying characteristics of near fault strong ground motions. Several strike slip rupture scenarios are generated to discuss effects of rupture propagation. Forward directivity pulses with large fault normal component are generated at the end of source fault in propagating direction in case of horizontally propagating ruptures. In the case, however, ground motions at rupture starting point on the source fault are very small. In case of vertical propagating ruptures from the bottom of faults, large fault parallel ground motions as expected in fault slip direction are generated around the source fault. In the case, ground motions on the fault line are very small. From the simulations, there exist some special cases that lead very small ground motions on the strike slip fault line as observed in several disastrous earthquakes, e.g. the 2016 Kumamoto Earthquake. Further minute study is required to explain the reason of the phenomenon completely.
