HR: 1340h
AN: T53A-1116    [Abstracts]
TI: Quantifying Geomorphology Associated With Large Subduction Zone Ruptures
AU: * Morgan, E C
EM: eugene.morgan@tufts.edu
AF: Tufts University Dept. of Civil and Environmental Engineering, 200 College Ave. Anderson Hall, Rm 113, Medford, MA 02155, United States
AU: McAdoo, B G
EM: brmcadoo@vassar.edu
AF: Vassar College Department of Geology and Geography, 124 Raymond Ave. Mail Drop 735, Poughkeepsie, NY 12604, United States
AU: Baise, L G
EM: laurie.baise@tufts.edu
AF: Tufts University Dept. of Civil and Environmental Engineering, 200 College Ave. Anderson Hall, Rm 113, Medford, MA 02155, United States
AB: For 30 rupture zones, we quantify forearc basin size and subducting seafloor roughness through a simple and traditional semivariance technique. The subduction of geomorphologic features, such as ridges and seamounts, increases basal erosion and subsidence of the accretionary wedge. Forearc basins form through such subsidence. Many subduction zone ruptures have been associated with these basins, where a great portion of the ruptures" asperities collocate with the basins. Mechanisms responsible for this spatial correlation include the initiation of stick-slip sliding beneath the accretionary wedge due to the subduction of bathymetric highs (e.g. seamounts), along-strike variations in crustal thickness and density of the overriding plate, and structural segmentation of the upper plate. Comparing the maximum semivariance (sill), the horizontal distance associated with the sill (range), and the fractal dimension of each rupture zone to the same parameters of the mirrored area on the subducting seafloor, we see a relationship between forearc and seafloor geomorphology, where rougher seafloor correlates to rougher forearc. Seafloor range, seafloor fractal dimension, and rupture zone fractal dimension all increase with earthquake moment magnitude. Additionally, we observe an increase in tsunami magnitude with range, suggesting some geomorphologic mechanism for tsunami earthquake generation.
DE: 3002 Continental shelf and slope processes (4219)
DE: 3045 Seafloor morphology, geology, and geophysics
DE: 3255 Spectral analysis (3205, 3280)
DE: 7240 Subduction zones (1207, 1219, 1240)
DE: 8170 Subduction zone processes (1031, 3060, 3613, 8413)
SC: Tectonophysics [T]
MN: 2007 Fall Meeting