JFAST for understanding of huge tsunamigenic slip during Tohoku-Oki earthquake

Abstract

The Japan Trench Fast Drilling Project (JFAST) demonstrated that the shallow plate boundary fault was weak during the 2011 M_w 9.0 Tohoku-Oki earthquake. This conclusion is derived from: (1) the high fraction of smectite in the fault, (2) high-velocity friction experiments on fault material showing low shear resistance, (3) the low temperature anomaly on the fault, and (4) the decreased in situ horizontal stress in the frontal prism above the fault.