The plate coupling in the Tokai District, the Central Japan, inferred from the different data using triangular dislocation elements

We estimate interseismic coupling on the subducting plate interface in the Tokai area, central Japan, by inverting two geodetic data sets. The data record surface motion between March 1996 to May 2000; one represents vertical motion deduced from the leveling observations and the other is the horizontal velocity field deduced from GPS observations. In the inversion, we employed the analytical solutions of surface displacement due to a triangular dislocation element embedded in a homogeneous elastic half space in order to represent the curved plate interface. The vertical data show that the most strongly coupled portion of the subduction interface is concentrated beneath Omaezaki Cape, while the horizontal data show strongest coupling in the shallower region of the subducting plate interface. The estimated maximum value of coupling from the horizontal data is 40 mm/year, while that from vertical data is 25 mm/year.

Research highlights► The strongly coupled area is estimated by horizontal and vertical data. ► The results show quite different coupling pattern. ► The different type of data may make different pattern of estimated coupling. ► Bias in data distribution would be a degrading factor of its importance.