URI_Research_Magazine_2010-2011_Melissa-McCarthy

multi- and interdisciplinary research

Tsunamigenic Submarine Landslides

Mudslides in California usually make the nightly news, with all the costly destruction they cause; million-dollar homes cascading down hillsides, gigantic trees toppling over as if they were twigs. But there are other landslides most people never hear of because they take place deep in the ocean. Yet these submarine landslides, as they are called, have much to reveal not only about the geological history of Earth, but also about the risk of similar landslides occurring today. Submarine landslides have also been linked to tsunamis: As the sand falls away during a submarine slide, it creates a depression, which in turn can generate a giant wave like the one that devastated several countries in Southeast Asia in December 2004. In contrast, the tsunami that recently hit Japan in March 2011 was caused by movement of the Earth’s crust due to an earthquake.

landslide that occurred off the continental slope in the Atlantic Ocean approximately 80 miles due east of Long Island. By studying cores of sediment extracted from the site, Baxter will be able to determine when the slide occurred. This is important, Baxter added, because if it turns out to have taken place more than 30,000 years ago, it can be placed in a specific geological age, with specific geological conditions. If it is less than 10,000 years old, it is considered still new – by geological standards at least – and therefore the conditions that existed then can help to predict if the world is at risk of a similar occurrence today. No one is predicting that a tsunami is going to crash onto New England’s shoreline anytime soon, Baxter said, noting, “The probability of tsunamis on the East Coast is not big.” Nonetheless, given the consequences of nuclear disasters such as those experienced in Japan, the Nuclear Regulatory Commission (NRC) is funding research to assess all possible risks including tsunamis as part of its responsibility to ensure safe sitting of nuclear power plants. Specifically, the NRC has contracted the U.S. Geological Survey (USGS) at the Woods Hole Coastal and Marine Science Center, which in turn is funding Baxter’s study of the submarine slide in the Atlantic Ocean. Baxter’s multidisciplinary research includes working with Jason Chaytor, a USGS marine geologist on the study. He also works regularly with one of URI’s tsunami experts, Stephan Grilli, distinguished professor of ocean engineering. Using the R/V Oceanus , one of three research vessels stationed at Woods Hole, MA, Chaytor led an expedition in June 2010 to the site of the submarine slide, which took place off the continental slope about 6,000 feet under water. Once there, the researchers extracted about 400 feet of sediment by drilling 20 cores, which Baxter began studying when the expedition returned last summer. Submarine landslides don’t happen all the time, noted Baxter. The

Christopher Baxter, joint associate professor of ocean engineering and civil and environmental engineering, studies these submarine landslides in his laboratory at the University of Rhode Island (URI) Narragansett Bay Campus. The goal, he said, is to determine the various conditions that existed when the underwater slide occurred to predict when a landslide might happen again. Of particular interest to Baxter is a submarine

Christopher Baxter

The University of Rhode Island 16