Weak interplate coupling beneath the subduction zone off Fukushima, NE Japan, inferred from GPS/acoustic seafloor geodetic observation
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We have been carrying out GPS/acoustic seafloor geodetic observations at several reference points situated along the Japan Trench, a major plate boundary of subduction. A time series of horizontal coordinates of one of the seafloor reference points, located off Fukushima, obtained from seven campaign observations for the period 2002-2008, exhibits a linear trend with a scattering root mean square of about 3 cm. A linear fit to the time series gives an intraplate crustal movement velocity of 3.1 cm per year in a westerly direction, which is significantly smaller than that at the other seafloor reference point 120 km away along the trench axis. This result implies weak interplate coupling in this region.
Key wordsGPS/acoustic seafloor geodetic observation back-slip Off Fukushima intraplate deformation
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