a Map of the study area.
Solid triangles and triangles outlined with thin lines indicate the
stations used in the source inversion (SI, Fig. 3), and the stations used to compare
observation and forward ground-motion simulation (FS,
Fig. 4), respectively.
Triangles outlined with thick lines indicate the stations used in
both analyses (SI and FS). The color of the triangles indicates the
observation network: blue, red, and green are KiK-net, K-NET, and
F-net, respectively. Black and coral stars indicate the epicenters
of the 2018 Hokkaido Eastern Iburi earthquake and the aftershock
5.4) at 6:11 JST on September 6, 2018, respectively. Focal
mechanisms refer to the F-net moment tensor solutions. The black
line denotes the outline of the curved fault model used in the
source inversion. Magenta lines denote the surface traces of the
active fault zone along the eastern margin of the Ishikari lowland
(AIST 2007). b Map view of the curved fault model.
Circles denote hypocenters of the aftershocks (M ≥ 1) within 1 day after the
mainshock. The color of the circles indicates the event depth.c Distribution of strike angle
on the curved fault model