Earth Planets Space, Vol. 52 (No. 11), pp. 1107-1112, 2000LETTER
Gamal S. El-Fiky
National Research Institute of Astronomy and Geophysics, Helwan, Cairo, Egypt
(Received November 25, 1999; Revised June 4, 2000; Accepted August 3, 2000)
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 mstrains/yr. Compared this with the rate of total strains of the order of 0.1 mstrains/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.