Surface Fault Rupture through a Ridge in an Aftershock of the 2011 Tohoku Earthquake

摘要

Surface fault rupture resulted from the 11 April 2011 M_w 6.6 Hamadoori aftershock of the 2011 M_w 9.0 Tohoku earthquake. This paper documents the surface rupture pattern and its interaction with a school gymnasium and pool. Locally along the rupture, surface offset was distinct, but at the school site, ground deformation was distributed across a wide zone. LIDAR-derived data show that the structures were tilted and warped as a result of surface rupture. Numerical analysis shows that semi-consolidated Tertiary sedimentary rocks were ductile and that prior fault ruptures may have not developed fully within the surficial materials. This is analogous to surface rupture interactions with engineered fills that exhibit ductile responses.