title: Seafloor observations indicate spatial separation of coseismic and postseismic slips in the 2011 Tohoku earthquake.
abstract: Large interplate earthquakes are often followed by postseismic slip that is considered to occur in areas surrounding the coseismic ruptures. Such spatial separation is expected from the difference in frictional and material properties in and around the faults. However, even though the 2011 Tohoku Earthquake ruptured a vast area on the plate interface, the estimation of high-resolution slip is usually difficult because of the lack of seafloor geodetic data. Here using the seafloor and terrestrial geodetic data, we investigated the postseismic slip to examine whether it was spatially separated with the coseismic slip by applying a comprehensive finite-element method model to subtract the viscoelastic components from the observed postseismic displacements. The high-resolution co- and postseismic slip distributions clarified the spatial separation, which also agreed with the activities of interplate and repeating earthquakes. These findings suggest that the conventional frictional property model is valid for the source region of gigantic earthquakes.
authors.affiliation: Research and Development Center for Earthquake and Tsunami, Japan Agency for Marine-Earth Science and Technology, Yokohama 236-0001, Japan.
authors.forename: Takeshi
authors.identifier: 0000-0003-0386-2055
authors.initials: T
authors.lastname: Iinuma
authors.affiliation: Research Center for Prediction of Earthquakes and Volcanic Eruptions, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan.
authors.forename: Ryota
authors.initials: R
authors.lastname: Hino
authors.affiliation: Research Center for Prediction of Earthquakes and Volcanic Eruptions, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan.
authors.forename: Naoki
authors.initials: N
authors.lastname: Uchida
authors.affiliation: Research Center for Prediction of Earthquakes and Volcanic Eruptions, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan.
authors.forename: Wataru
authors.initials: W
authors.lastname: Nakamura
authors.affiliation: Disaster Science Division, International Research Institute of Disaster Science, Tohoku University, Sendai 980-0845, Japan.
authors.forename: Motoyuki
authors.initials: M
authors.lastname: Kido
authors.affiliation: Research Center for Prediction of Earthquakes and Volcanic Eruptions, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan.
authors.forename: Yukihito
authors.initials: Y
authors.lastname: Osada
authors.affiliation: Research Center for Prediction of Earthquakes and Volcanic Eruptions, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Miura