Transient crustal deformation in Tokai region, central Japan, until May 2004

An analysis of Global Positioning System (GPS) data reveals a continuation of the transient crustal deformation that was first reported by Ozawa et al. (2002) in the western Tokai region. Kalman filtering following the time-dependent inversion shows a slow-thrust slip occurring on the plate boundary in the western Tokai region, with its center around Lake Hamana, which is adjacent to the anticipated Tokai earthquake source area. The moment release from the Tokai silent earthquake was observed to be continuous surpassing M_w 7.0 in May 2004, with relative slip increases to the northeast and north of Lake Hamana from 2002. The moment release rate decreased in 2002, and then increased in 2003, reaching the rate observed in 2001.