Discovery of submarine landslide evidence due to the 2009 suruga bay earthquake

Abstract

On August 11, 2009, at 05:07 JST, a moderate- To-large earthquake took place in the Suruga Bay of central Japan. It struck two deep-sea water pipes in the source area. Immediately after the event, both the temperature and the turbidity of the waters increased significantly. Surveys carried out in the source area revealed the level of damage to the water pipes. In this study, we report on the results of the visual survey performed by the remotely operated vehicle Hyper-Dolphin and the bathymetric data collected by the research vessel Natsushima. We found that one water pipe was moved at least 2 km downstream from its original location. The bathymetries obtained before and after the earthquake identified two types of geomorphologic features related to submarine landslide in the approximately 20 km2 region. One of the features consists of extensive deepening and shallowing patterns newly created in the source area, suggesting mass slide traces processed during the earthquake. The other feature consists of a slide scar, slide blocks, and slope failures created locally in the upstream direction of the water pipe. This latter feature is evidence that mass slide took place and eventually moved the water pipe during the Suruga Bay earthquake. © Springer Science+Business Media B.V. 2012.