Comparative study between present and emergent erosional landforms on the southeast coast of Boso Peninsula, central Japan.

Abstract

The SE coast of Boso Peninsula experienced abrupt uplifts associated with the 1703 and 1923 great earthquakes, the amounts of which were 3-6m and 1-2m, respectively. A flight of Holocene marine terraces, lower than 30m above sea level, on the coast has been classified into 4 levels separated by low scarps, about 5m high. From these facts it has been interpreted that the coast was intermittently uplifted 4 times in about 6000yr. Terrace surfaces, however, are further subdivided by low scarps, about 1m high, and terrace scarps usually descend stepwise. This suggests that the coast has been uplifted many times associated also with smaller earthquakes. Judging from height intervals of raised shorelines it is concluded that the S part of Boso Peninsula has experienced intermittently 4 major uplifts with each amount of 3-6m and 2 or 3 minor uplifts with that of 1-2m intercalated between consecutive 2 major uplifts, which were probably associated with earthquakes similar in magnitude of displacement to the 1703 and 1923 seismic events, respectively. -from English summary