Evidence for Earthquake Shaking at Archaeological Sites near the Sagami Bay Region in Southern Kanto, Japan

摘要

Evidence of paleo-earthquakes, including cracks, quicksand, and landslides, can be recognized at archaeological sites around the Sagami Bay region. Based on this evidence, we can reconstruct the occurrences of paleo- earthquakes and damage caused by ground motion and faulting. In the fault zone at the northern margin of Izu Peninsula, earthquakes are estimated to have occurred at the following times : (1) about 5,000 yrs BP; (2) 2,800--3,000 yrs BP; (3) from about 3,000 yrs BP to AD 100, (4) from AD 687 to 750; and (5) after 1707 (prob- ably in 1853). At the southeast margin of the Tanzawa Mountains and the Oiso Hills, traces of earthquake occurrence point to the follow- ing time : (1) the 4th century and from the second half of the 5th century to the first half of the 6th century, (2) from 687 to 750, (3) the second half of the 8th century; and (4) the 9th century. From the Sagami River to the Miura Peninsula, traces of earthquakes that occurred from AD l00 to 400 and in the 9th century are concentrated along the linear zone connecting the Ebina and Kamakura areas.