HR: 10:40h
AN: T52A-02    [Abstracts]
TI: Comparison of Holocene With Coseismic Vertical Deformation Accompanying the Great 1 April 2007 Solomon Islands Megathrust Rupture
AU: * Taylor, F W
EM: fred@ig.utexas.edu
AF: Inst. Geophysics, Jackson School of Geosciences Univ. Texas at Austin, Austin, TX 78758, United States
AU: Briggs, R
EM: briggs@gps.caltech.edu
AF: Tectonics Observatory, California Inst. Technology, Pasadena, CA 91125, United States
AU: Frohlich, C
EM: cliff@ig.utexas.edu
AF: Inst. Geophysics, Jackson School of Geosciences Univ. Texas at Austin, Austin, TX 78758, United States
AU: Papabatu, A K
EM: papabatu@mines.gov.sb
AF: Dept. Mines, Energy, Water, Ministry Natural Resources, Honiara, PMB, Solomon Islands
AU: Billy, D
EM: d_billy@mines.gov.sb
AF: Dept. Mines, Energy, Water, Ministry Natural Resources, Honiara, PMB, Solomon Islands
AU: Brown, A
EM: brown.2179@osu.edu
AF: School of Earth Sciences, Ohio State Univ., Columbus, OH 43210, United States
AU: Meltzner, A J
EM: meltzner@gps.caltech.edu
AF: Tectonics Observatory, California Inst. Technology, Pasadena, CA 91125, United States
AB: The 1 April 2007 Mw 8.1 earthquake in the western Solomons arc is the first major seismic rupture of this segment of plate boundary in historical times. A remarkable property of this region is the existence of coral- fringed islands located in a belt from ~90 km to as close as ~5 km from the trench. This setting provides a unique opportunity in which to measure forearc vertical movements using corals and other data to reveal relationships among coseismic vertical displacement, extremely rapid uplift of the outer forearc, and slower uplift of the main volcanic arc. The location of maximum coseismic uplift along a trench-parallel belt adjacent to the trench is consistent with the trench-parallel belt of maximum Holocene uplift rates. However, islands along the main volcanic arc lie in the swath of coseismic subsidence located arcward and parallel to the uplift zone. These islands typically have mean Holocene uplift rates up to ~1mm/yr. Thus, coseismic uplift correlates with rapid outer forearc Holocene uplift, but coseismic subsidence occurred throughout the more slowly uplifting volcanic arc. Using these observations, we can deconvolve and isolate the components of co- seismic, interseismic, and net vertical deformation and seek to address the underlying mechanisms. Interpretation is complicated by the late Quaternary history that includes subsidence of both the inner and outer arc islands prior to initiation of the ongoing net uplift since ~50 ka.
DE: 1209 Tectonic deformation (6924)
DE: 1242 Seismic cycle related deformations (6924, 7209, 7223, 7230)
DE: 7230 Seismicity and tectonics (1207, 1217, 1240, 1242)
DE: 7240 Subduction zones (1207, 1219, 1240)
DE: 8170 Subduction zone processes (1031, 3060, 3613, 8413)
SC: Tectonophysics [T]
MN: 2007 Fall Meeting