Fig. 1

Distribution of the source areas of recent large interplate earthquakes off Miyagi prefecture and the 2011 Tohoku-Oki earthquake. Black dashed contours: coseismic slip distribution (10 and 50 m) of the 2011 Tohoku-Oki earthquake (Iinuma et al. 2012). Gray lines: distribution of the estimated postseismic slip (> 0.4 m) for 0.6 years following the 2011 Tohoku-Oki earthquake (Iinuma et al. 2016). Black and gray stars indicate the hypocenters of the mainshock (Mj = 9.0) and foreshock (Mj = 7.3) of the 2011 event, respectively, determined by JMA. The magenta and orange areas indicate the source areas (slip > 0.6 m) of the 1978 and 2005 Miyagi-ken-Oki earthquakes, respectively (Yamanaka and Kikuchi 2004; Yamanaka 2005). The red and green stars indicate the hypocenters of the March and May 2021 earthquakes determined by JMA. The gray region on land surrounded by the solid line indicates the location of Miyagi Prefecture. The brown line indicates the plate boundary (Bird 2003). The rectangle in the inset with the plate boundary (Bird 2003) represents the location of the study area. PA Pacific plate, PS Philippine Sea Plate, AM Amur plate, OK Okhotsk plate