Abstract
Coseismic uplift probably contributed to the emergence of Holocene marine terraces around Sagami Bay. The highest of these terraces emerged about 6, 000 years ago. Its height distribution reflects subduction of the Philippine Sea Plate, collision of part of this plate (Izu Peninsula), and crustal shortening in the continental plate.
Two kinds of coseismic uplift probably occur at eastern Sagami Bay, on the southern part of the Boso Peninsula. One type, represented by the Kanto earthquake of 1923 (in the Taisho era), was due to interplate slip along the Sagami Trough. The other type is represented by the Kanto earthquake of 1703 (in the Genroku era), the hypocentral area of which consists of the area along Sagami Trough and its southeastern extension. Various combinations of Taisho and Genroku earthquakes can account for the height of the highest Holocene marine terrace on the Boso Peninsula. The best such combination gives a mean recurrence interval of 500-600 years for Taisho-type earthquakes.
Since the accuracy and resolution of the height and formative age have not been so high, a consistent explanation of the formative history of Holocene marine terraces throughout Sagami Bay area remains to be given.
