Interplate thrust earthquakes are usually followed by afterslips, and they let the fore-arc move slowly
trenchward. However, we do not know if the subducting oceanic plate is accelerated landward after
such earthquakes. The westward velocity of Global Positioning System (GPS) stations in NE Japan show
gradient decreasing from east to west reflecting the E-W contractional strain built up by the inter-plate
coupling. Here we show that such coupling significantly enhanced (1.5 times) after the 2003 TokachiOki
earthquake (Mw 8.0), Hokkaido, in the segments adjacent to the ruptured fault. The coupling seems
to be further enhanced (3 times) after the 2011 Tohoku-Oki earthquake (Mw 9.0). It is unlikely that
interplate friction suddenly increased over such a large region, and relatively strong pre-2003 coupling
there would not allow such enhancements even if full coupling is attained. Hence they are attributable
to the temporary acceleration of the Pacific Plate subduction. We propose a simple 2-dimensional
model in which down-dip acceleration of the slab let the force balance rapidly recover promoted by a
thin low-viscosity layer on the slab surface. The accelerated subduction would account for temporary
activations of regional interplate seismicity after megathrust earthquakes.