Figure 1

Regional and survey location maps. (A) Black lines are the regional seismic lines and green lines are the high-resolution seismic lines. The green box is the location of the inlet in the upper left corner showing high-resolution seismic line locations with yellow sections marking shown sections. The red circle is location of IODP Site C0019 (J-FAST). The dashed white line is the trace of the deformation front. Labeled red boxes are locations of Figures 2, 3 and 9. The rose diagram displays the strike of topographic structures within 38° to 39° 20′ N (modified from Nakanishi 2011). Abbreviations on the rose diagram are as follows: Fz, fracture zone; Tn, trench trend north of 38° N; Ts, trench trend south of 38° N; M38, magnetic anomaly orientation near 38° N; M, magnetic anomaly orientation elsewhere. Black dashed oval shows area of petite spot volcanoes (Hirano et al. 2008); (B) slope map of the Pacific Plate is overlain on top of the bathymetry, highlighting normal fault scarps (dark regions). Arrows point to seaward trench-parallel fault scarps outside the region of the 2D seismics. Black line marks the deformation front. Colored profiles indicate the stratigraphic thickness of the sediment column of the Pacific Plate. Thinning near normal faults is expected. (C) Regional tectonic map. The yellow star is the location of the 2011 Tohoku earthquake epicenter. The red box is the location of Figure 1A,B. Green circle is the location of Deep Sea Drilling Project (DSDP) Site 436. White arrows show the convergence direction of the Pacific Plate.