COSEISMIC CRUSTAL DEFORMATION FROM THE 1994 HOKKAIDO-TOHO-OKI EARTHQUAKE MONITORED BY A NATIONWIDE CONTINUOUS GPS ARRAY IN JAPAN

Using a brand-new nationwide continuous GPS array, we monitored coseismic displacements from the October 4, 1994, Hokkaido-Toho-Oki (Kurile islands) earthquake (M(JMA)=8.1). Based on 2-week time series of site coordinates of 21 GPS stations, we present a coseismic deformation field of whole Hokkaido within 1 cm precision. For example, the station at Nemuro, 170 km west of the epicenter, moved 44 cm to the east and subsided 10 cm. Even stations in southern Hokkaido, 600 km apart from the epicenter, moved a few cm horizontally toward the epicenter. We compare the GPS result with displacements calculated from two preliminary models, assuming fault planes parallel or perpendicular to the Kurile trench. Since the observed were far-field displacements on land, both models can explain the GPS result.