title: Stress state in the largest displacement area of the 2011 Tohoku-Oki earthquake.
abstract: The 2011 moment magnitude 9.0 Tohoku-Oki earthquake produced a maximum coseismic slip of more than 50 meters near the Japan trench, which could result in a completely reduced stress state in the region. We tested this hypothesis by determining the in situ stress state of the frontal prism from boreholes drilled by the Integrated Ocean Drilling Program approximately 1 year after the earthquake and by inferring the pre-earthquake stress state. On the basis of the horizontal stress orientations and magnitudes estimated from borehole breakouts and the increase in coseismic displacement during propagation of the rupture to the trench axis, in situ horizontal stress decreased during the earthquake. The stress change suggests an active slip of the frontal plate interface, which is consistent with coseismic fault weakening and a nearly total stress drop.
authors: Kochi Institute for Core Sample Research, Japan Agency for Marine-Earth Science and Technology, Nankoku, Japan. lin@jamstec.go.jp
authors: Weiren
authors: W
authors: Lin
authors: Marianne
authors: M
authors: Conin
authors: J Casey
authors: JC
authors: Moore
authors: Frederick M
authors: FM
authors: Chester
authors: Yasuyuki
authors: Y
authors: Nakamura
authors: James J
authors: JJ
authors: Mori
authors: Louise
authors: L
authors: Anderson
authors: Emily E
authors: EE
authors: Brodsky
authors: Nobuhisa
authors: N
authors: Eguchi