Numerical analysis of the mobility of the Palos Verdes debris avalanche, California, and its implication for the generation of tsunamis

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Title: Numerical analysis of the mobility of the Palos Verdes debris avalanche, California, and its implication for the generation of tsunamis
Authors: Locat, Jacques1 locat@ggl.ulaval.ca, Lee, Homa J.2, Locat, Pascal1, Imran, Jasim3
Source: Marine Geology. Jan2004, Vol. 203 Issue 3/4, p269. 12p.
Subjects: Morphology, Avalanches, Tsunamis, Earthquakes
Abstract: Analysis of morphology, failure and post-failure stages of the Palos Verdes debris avalanche reveals that it may have triggered a significant tsunami wave. Our analysis of the failure itself indicates that the slope is stable under aseismic conditions but that a major earthquake (with a magnitude around 7) could have triggered the slide. A post-failure analysis, considering the debris avalanche as a bi-linear flow, shows that peak velocities of up to 45 m/s could have been reached and that the initial movement involved a mass of rock less than 10 km wide, 1 km long and about 50–80 m thick. Initial wave height estimates vary from 10 to 50 m. Tsunami waves propagating to the local shoreline would be significantly smaller. Such a range demonstrates our lack of proper knowledge of the transition from failure to post-failure behavior related to mass movements. Further investigations and analyses of terrestrial and submarine evidence are required for a proper hazard assessment related to tsunami generation in the Los Angeles area. [Copyright &y& Elsevier]
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Database: Engineering Source
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Abstract:Analysis of morphology, failure and post-failure stages of the Palos Verdes debris avalanche reveals that it may have triggered a significant tsunami wave. Our analysis of the failure itself indicates that the slope is stable under aseismic conditions but that a major earthquake (with a magnitude around 7) could have triggered the slide. A post-failure analysis, considering the debris avalanche as a bi-linear flow, shows that peak velocities of up to 45 m/s could have been reached and that the initial movement involved a mass of rock less than 10 km wide, 1 km long and about 50–80 m thick. Initial wave height estimates vary from 10 to 50 m. Tsunami waves propagating to the local shoreline would be significantly smaller. Such a range demonstrates our lack of proper knowledge of the transition from failure to post-failure behavior related to mass movements. Further investigations and analyses of terrestrial and submarine evidence are required for a proper hazard assessment related to tsunami generation in the Los Angeles area. [Copyright &y& Elsevier]
ISSN:00253227
DOI:10.1016/S0025-3227(03)00310-4