Slip behaviors extracted from decadal seafloor geodesy after the Tohoku-oki earthquake

Investigations of the co- and postseismic processes of the 2011 Tohoku-oki earthquake provide essential information on the seismic cycle in the Japan Trench. Although various postseismic models have been proposed, no consensus has been reached, especially on the along-strike extensions of the main rupture due to the lack of conclusive evidence, even in the coseismic process. To capture aseismic behaviors that restrain coseismic rupture propagation, it is necessary to perform long-term postseismic geodetic observation on the seafloor. Here, we provide empirical evidence for aseismic afterslip on the rupture edges by decomposing elementary postseismic processes from decadal seafloor geodetic data. The results suggest that the tsunami-derived shallow coseismic slip should be adopted in the viscoelastic relaxation model to reasonably explain the spatiotemporal variation of seafloor deformation.