HR: 0800h
AN: OS31A-0166    [Abstracts]
TI: Three-dimensional simulation of a rock slide impact into water
AU: Weaver, R
EM: lwsunset@qwest.net
AF: Los Alamos National Laboratory, PO Box 1663, Los Alamos, NM 87545, United States
AU: * Gisler, G
EM: galen.gisler@fys.uio.no
AF: Physics of Geological Processes University of Olso, PO Box 1048 Blindern, Oslo, 0316, Norway
AU: Gittings, M
EM: gittings@lanl.gov
AF: Science Applications International Corporation, 10620 Campus Point Drive, La Jolla, CA 92121, United States
AU: Ranta, D
EM: dir@lanl.gov
AF: Science Applications International Corporation, 10620 Campus Point Drive, La Jolla, CA 92121, United States
AB: The steep-sided fjords of western Norway have experienced numerous rock slide events that sometimes produced devastating tsunamis. The 1934 slide in the Tafjord region, when some 3 million cubic meters of rock plunged into the water, resulted in waves tens of meters high that destroyed two villages and killed about 40 people. A similarly dangerous situation exists now in Sunnylvsfjord, where a major expanding crack in the fjord wall at Aknes threatens to release from 5 to 40 million cubic meters of rock into the water. Such an event would devastate a large region, including the Geiranger Fjord, a UN World Heritage Site that is extremely popular with tourists. The Norwegian Government's Aknes-Tafjord project is responsible for studying and monitoring the potential slide area and for providing adequate warning to protect lives and property. In order to better understand tsunami generation from such events, we have performed 3-dimensional fully compressible hydrodynamical simulations of the impact of a large number of boulders from a steep slope into a deep body of water. We use the Los Alamos/SAIC adaptive-mesh-refined SAGE code, previously used to model tsunamis from underwater explosions, asteroid impacts, and both subaqueous and subaerial landslide sources. We find the interaction of boulders and water to be extremely turbulent and dissipative. It differs markedly from simulations of large-block impacts in similar geometry. No more than about 15% of the potential energy of the boulders ends up in the water wave. The rest of the energy goes into heating the boulders (and presumably fragmenting them, though that physics is not included) into generating winds, heating air and water, and generating turbulence. In the near field, the waves produced by the impact can be quite high -- tens of meters -- and have the potential to devastate coastlines at substantial distances from the site along a narrow fjord system.
DE: 4564 Tsunamis and storm surges
SC: Ocean Sciences [OS]
MN: 2007 Fall Meeting