Study of great earthquakes by means of satellite altimetry and Synthetic aperture radar.

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1. We carried out a research to eliminate the meteorological disturbance on the differential interferometry of SAR data by using a JMA regional numerical model. The technique enables us to detect long wavelength undulated fringes at western coast of Korean Peninsula by ERS-1 satellite radar interferometry. Though the amplitude in the derived interferogram is larger than that of prediction, the spatial pattern is similar to the theoretical computation of inland flexural response to the ocean tide in the Yellow Sea.2. We developed a recipe to compute gravity/geoid height change and vertical displacement caused by a point dislocation in a spherical, viscoelastic and self-gravitating earth. It enables us to trace the crustal deformation excited by a great earthquake. Time evolutions for a point source located in the elastic lithosphere is distinctively different from that when a source is in the viscoelastic asthenosphere.3. As a first step toward a numerical modeling of global internal tide field, the distribution of the M2 internal tide in the North Pacific is examined using a three-dimensional primitive equation numerical model. The numerical simulation shows that energetic internal tides are generated over the prominent bottom topographies in the Indonesian Archipelago, the Solomon Archipelago, the Aleutian Archipelago as well as over the continental shelf slope in the East China Sea, the Izu-Ogasawara Ridge and the Hawaiian Ridge. In particular, the calculated spatial distribution of the M2 internal tide around the Hawaiian Ridge agrees very well with that obtained from the Topex/Poseidon altimetry.