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GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS, VOL. 8, Q12008, doi:10.1029/2007GC001722, 2007

Triggering mechanism and tsunamogenic potential of the Cape Fear Slide complex, U.S. Atlantic margin

Matthew J. Hornbach

Institute for Geophysics, University of Texas, 4412 Spicewood Springs Road, Building 600, Austin, Texas 78759, USA


Luc L. Lavier

Institute for Geophysics, University of Texas, 4412 Spicewood Springs Road, Building 600, Austin, Texas 78759, USA


Carolyn D. Ruppel

U.S. Geological Survey, 384 Woods Hole Road, Woods Hole, Massachusetts 02543, USA


Abstract

Analysis of new multibeam bathymetry data and seismic Chirp data acquired over the Cape Fear Slide complex on the U.S. Atlantic margin suggests that at least 5 major submarine slides have likely occurred there within the past 30,000 years, indicating that repetitive, large-scale mass wasting and associated tsunamis may be more common in this area than previously believed. Gas hydrate deposits and associated free gas as well as salt tectonics have been implicated in previous studies as triggers for the major Cape Fear slide events. Analysis of the interaction of the gas hydrate phase boundary and the various generations of slides indicates that only the most landward slide likely intersected the phase boundary and inferred high gas pressures below it. For much of the region, we believe that displacement along a newly recognized normal fault led to upward migration of salt, oversteepening of slopes, and repeated slope failures. Using new constraints on slide morphology, we develop the first tsunami model for the Cape Fear Slide complex. Our results indicate that if the most seaward Cape Fear slide event occurred today, it could produce waves in excess of 2 m at the present-day 100 m bathymetric contour.

Received 13 June 2007; accepted 15 October 2007; published 28 December 2007.

Keywords: submarine slides; tsunami; gas hydrates; continental margins; salt tectonics.

Index Terms: 3070 Marine Geology and Geophysics: Submarine landslides; 4564 Oceanography: Physical: Tsunamis and storm surges; 3004 Marine Geology and Geophysics: Gas and hydrate systems; 8105 Tectonophysics: Continental margins: divergent (1212, 8124).

Subscriber Access to Full Article (Nonsubscribers may purchase for $9.00, Includes print PDF, file size: 1056133 bytes)

Citation: Hornbach, M. J., L. L. Lavier, and C. D. Ruppel (2007), Triggering mechanism and tsunamogenic potential of the Cape Fear Slide complex, U.S. Atlantic margin, Geochem. Geophys. Geosyst., 8, Q12008, doi:10.1029/2007GC001722.