Plate geometry model and seismicity in the northern Ryukyu subduction zone, Japan, deduced from amphibious seismic observations

Abstract In this study, the geometry of the subducted Philippine Sea Plate interface beneath the northern Ryukyu Trench subduction zone was estimated based on seismic tomography and focal mechanism estimations using passive data obtained from a temporary amphibious seismic network and permanent land stations. Using relocated low-angle thrust-type earthquakes and information obtained from previous studies, we constrained the plate geometry from the trench axis to a depth of 60 km with uncertainties of