Abstract
This paper reviews the studies on seismic activities and tectonics in southwestern Japan. We start with the stress state of southwestern Japan with reference to movements of the Philippine Sea plate, the Eurasian plate and other concerning plates. Then we describe subcrustal seismic activity associated with the subduction of the Philippine Sea plate and shallow earthquakes occurring in the upper crust in relation to the active faults and mechanical properties of the crust. We also give a brief summary of studies on microearthuakes in the concerned districts.
