箱根火山芦ノ湖の湖底における箱根町断層地形

概要

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The bottom topography of lake Ashi-no-ko, in the Hakone volcano caldera, was examined using the SeaBat8101 narrow multi-beam sonar system. The purpose of micro-topographical observations of the lake bottom is to understand the tectonic relations between the historical formation-process of the caldera and the strike-slip motion in the Tanna-Hirayama active fault system. At the southeastern part of the lake, west of the Dougashima, undulations at the bottom such as swells, hollows, and stairs extending in the northwest-southeast direction, were observed. These bottom-forms show a northern extension of the Hakonemachi active fault, running along the east side of lake Ashi-no-ko. They may correspond to one of the north spray faults of the Kita-Izu active fault system, which is the source of the A.D.1930 Kita-Izu earthquake, and to motions of the western margin of the Manazuru micro-plate, in relation to caldera formation as a strike-slip basin.
社団法人東京地学協会の論文
2010-10-25