1. Mechanism of subsidence of the Northeast Japan forearc during the late period of a gigantic earthquake cycle
- Author
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Yoshihiko Nakai, Hikaru Iwamori, Ryohei Sasajima, Bunichiro Shibazaki, and Takuya Nishimura
- Subjects
0301 basic medicine ,Multidisciplinary ,Mantle wedge ,Subduction ,lcsh:R ,lcsh:Medicine ,Slip (materials science) ,Geodynamics ,Article ,03 medical and health sciences ,030104 developmental biology ,0302 clinical medicine ,Lithosphere ,lcsh:Q ,Shear zone ,lcsh:Science ,Forearc ,Seismology ,030217 neurology & neurosurgery ,Geology ,Asperity (materials science) - Abstract
The forearc in Northeast Japan subsided (3–4 mm/year) in the interseismic ~100 years before the 2011 Tohoku earthquake (MW9.1) just like it did during this event. This study attempts to understand the mechanism of the vertical displacement of the forearc during gigantic earthquake cycles via numerical modeling. The results suggest that the interseismic subsidence rate in the forearc increases with the duration of the locking of the asperity of the gigantic earthquake over several hundred years, due to the increasing slip deficit rate on the deeper parts of the plate interface. The increasing slip deficit rate is caused by both the decreasing the shear stress in the shear zone owing to the continuous locking of the asperity and the increasing the mobility of the continental lithosphere owing to the viscoelastic relaxation in the mantle wedge. The deep slip deficit rate extending to ~100 km depth of the plate interface is necessary to explain the observed interseismic forearc subsidence rate. The results also suggest hundreds of years of continuous locking of the asperities of a gigantic earthquake in the western Kuril subduction zone, where fast forearc subsidence has been observed as well., 東北地方太平洋沿岸域が沈降するメカニズムを解明 --超巨大地震サイクル後半の沈降速度の増加--. 京都大学プレスリリース. 2019-04-09.
- Published
- 2019