Maps showing distribution of seismic stations (squares) and hypocenters (solid colored circles). Earthquakes used for analysis at each station are depicted by different colors for each station. Rose diagrams show Φ and the number of data at each station. Values between 0° and 180° are plotted again between 180° and 360°, because the value of Φ is a nonvector direction. Solid lines indicate the fault strike beneath each station (Yukutake et al., 2011). Dotted lines show the orientation of the maximum horizontal compressional stress in this region, estimated from a stress inversion analysis (Yukutake et al., 2007). (a) Dashed line indicates outer rim of the Hakone caldera. The rectangle shows the area of Fig. 1(b). (b) Red and orange solid circles indicate Group-I and II events used in the analysis at KZR (see text). Gray dots indicate hypocenters of other earthquakes during the analysis period.