Fig. 1

Hypocenter distribution in around the Kii Peninsula, Japan. Dots represent hypocenters from the Japan Meteorological Agency (JMA) catalog shallower than or equal to 20 km for the period from 2005 to 2013. The color of each dot represents the depth to the event. Red rectangle represents the study area. Triangles indicate the seismograph stations belonging to JMA, NIED and Kyoto University used to determine the focal mechanisms in this study. Averaged distance between two adjacent stations is about 10 km, and hypocenters and focal mechanisms are determined using stations including a station with epicentral distance of less than 5 km in most cases