Geological and geomorphological features in broken gravels from the North Senoumi-bank, Suruga-bay, Japan and its implications on Mega-earthquakes

摘要

In the central part of Suruga Bay, the Suruga Trough, which developed in the north-south direction, exists. Senoumi-bank is located on the western side of the Suruga Trough and stepped steep slopes are observed on the eastern slope. On this steep slope, crushed sedimentary rocks are confirmed, and the 90% of the collected gravels have a broken shape. The presence of staircase topography and fractured gravel is thought to be caused by the activity of the thru st fault accompanied with the subduction of the Philippine Sea Plate beneath Eurasian Plate.