Fig. 4

Results of hypocenter determinations for first 6 days of observation. The events for which all six first arrivals were identified (P- and S-waves at three OBSs) are shown by yellow circles with error bars. Purple circles are events for which only five first arrivals were identified. Magnitudes were calculated by the method of Watanabe (1971). Red inverted triangles are OBS locations. Hypocenters of earthquakes recorded in the KOERI catalogue just before 1 week of OBS observation and between 20 March and 18 June 2014 are also shown as white and gray circles, respectively. Black fault lines indicate the fault model of Le Pichon et al. (2001) and red lines that of Armijo et al. (2005). Bathymetry (interval 100 m) is also shown. Blue rectangle indicates analysis area for Fig. 9