Fig. 1
From: Stress loading and the occurrence of normal-type earthquakes under Boso Peninsula, Japan
a Landforms around Boso Peninsula (BP) and the Kanto Basin (KB). Topography data from Smith and Sandwell (1997). IP: Izu Peninsula, SB: Suruga Bay, ST: Sagami Trough. Solid contours map upper surface of PHS plate, and dashed contours, upper surface of PAC plate. Blue line indicates structural high bounding forearc basin and trench slope. Focal mechanism marks location of Mw 4.9 normal-type earthquake of 2019/05/25. Thick black outline indicates best estimate of locked zone due to collision of the Izu-Bonin arc at Izu Peninsula (Hashima et al. 2016). Colored outlines show source/slip areas for 1703 Kanto earthquake (red) (Sato et al. 2016), 1923 Kanto earthquake (pink) (Matsu’ura et al. 2007), and Boso slow slip zone (purple) (Sato et al. 2017). b Slip rate distribution on plate interfaces around Japan used in our computations. Contours denote upper surfaces of PHS and PAC plates. Slip rates for PHS plate (thick arrow) and PAC plate (thin arrow) based on NUVEL-1A model (DeMets et al. 1994). 3-D plate interface data from CAMP model (Hashimoto et al. 2004). Star: hypocenter, 2011 M9 Tohoku earthquake. Red rectangle indicates area shown in a. Inset: Schematic illustration of internal structure and slip distribution in vertical section perpendicular to the trench. See text for parameter H and S