Elastic and inelastic strains in the Japanese Islands deduced from GPS dense array

Abstract

To estimate the elastic and inelastic strains in the Japanese Islands, we used horizontal velocity vectors at 917 sites of the nation-wide GPS network for the period April 1996 to March 1998. To segregate the signal and noise in the velocity vectors, we employed the Least-Squares Prediction technique (LSP). Estimated signals (displacement vectors) were differentiated in space to reconstruct the total strains (elastic plus inelastic). Then, we estimated inelastic strains of the islands using the inversion method introduced by Hori et al (1999). The estimated rate of inelastic strains is of the order of 10-3 μstrains/yr. Compared this with the rate of total strains of the order of 0.1 μstrains/yr, inelastic part was found to be negligible. Finally, shear stresses at the surface of the Japanese Islands have been estimated, based on the elasticity theory. Copy right© The Society of Geomagnetism and Earth, Planetary and Space Sciences (SGEPSS); The Seismological Society of Japan; The Volcanological Society of Japan; The Geodetic Society of Japan; The Japanese Society for Planetary Sciences.