Vol.43-1 ABSTRACT1
AbstractVertical crustal movements in the coastal areas of Japan have been estimated based on the method Kato and Tsumura (1979) using tidal records at more than 100 tidal stations since 1958. The results show that tidal stations in the coastal area facing the Pacific Ocean form Hokkaido through southern Tohoku have subsided at a rate between 3 and 10 mm/year during the period between 1958 and 1996. Tidal stations on the Boso and Miura peninsulas subside at a rate between 2 and 4 mm/year. Subsidence at the Omaezaki station at the tip of Cape Omaezaki shows a subsidence rate of about 7 mm/year, which is almost equal to that estimated from leveling surveys. Stations at the tip of the Kii peninsula and in the southern part of Shikoku island show subsidence. Annual crustal movements at tidal stations in Kyushu are very small during the period between 1958 and 1996. Along the Sea of Japan coast, vertical crustal movements are not remarkable. The characteristic features along the Sea of Japan coastal line are subsidence of station in Wakasa Bay, subsidence of the Ogi and Awashima stations, and upheavals at the Fukaura and Oga stations in northern Tohoku. During the period between 1978 and 1996, after Kato and Tsumura's research, several noteworthy events were observed. A very large upheaval on the east coast of the Izu peninsula was detected at tidal stations around the city of Ito on the Izu peninsula, which is associated with swarm activity around Ito since 1974. The Kagoshima station near the Sakurajima volcano shows subsidence that is probably due to deflation of the magma reservoir of the Sakurajima volcano. Several coseismic displacements were observed in association with the 1993 Kushiro earthquake, the 1993 Hokkaido Nansei-oki earthquake, the 1994 Hokkaido Toho-oki earthquake, the 1995 Sanriku earthquake, the 1995 Kobe earthquake, and others. |