Fig. 1
Map of the earthquake distribution associated with the 2016 Kumamoto earthquake sequence. The black and gray circles represent the earthquakes occurring within pre- and post-April 16 periods, respectively. The stars represent the epicenters of the April 14 (small star) and the April 16 (large star) events. The triangles and the red circles represent the Hi-net (KiK-net) stations and the source-grids for the energy release (located at 10 km depth) used for the envelope inversion analysis, respectively. The red rectangle in the inserted map represents the studied area