HR: 1340h
AN: T53A-1119    [Abstracts]
TI: Coseismic vertical deformation during the great 2007 Solomon Islands megathrust rupture
AU: * Briggs, R
EM: briggs@gps.caltech.edu
AF: Tectonics Observatory, California Institute of Technology, 1200 E. California Avenue, MC 100-23, Pasadena, CA 91125, United States
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: 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 Institute of Technology, 1200 E. California Avenue, MC 100-23, Pasadena, CA 91125, United States
AB: A joint US-Solomon Islands team visited the epicentral area of the 1 April 2007 M_w 8.1 Solomon Islands earthquake a few weeks after the event. We used coral microatolls, satellite imagery, and displaced geomorphic and cultural features to map the coseismic deformation pattern in the region directly above and adjacent to the subduction megathrust rupture. Among our main findings is that most slip occurred on the shallow portion of the megathrust and that slip appears to have reached the deformation front at Ranongga island, which was uplifted as much as ~2.5 m when the rupture propagated across the subducting Simbo ridge transform. Simbo island, which sits on the downgoing Australian plate and lies only 8 km across the plate boundary from uplifted Ranongga, subsided ~0.7 m coseismically and experienced only subdued ground motions. The line of zero vertical displacement (hingeline) runs closely along the southwestern coasts of Vella Lavella, Ghizo, and Parara islands, implying a persistent structural relationship between the downdip limit of coseismic slip and these coastlines. A broad, asymmetrical subsidence trough as deep as ~0.7 m extends across Vella Lavella, Kolombangara, Parara, and New Georgia. Uplift of ~0.35 m on the westermost tip of Rendova, along with overall subsidence of Rendova and Tetepare, place a firm limit on the southeastern extent of rupture. Uplift of Mono and subsidence of Fauro and the Shortlands, and no resolvable vertical change on Bougainville, define a rupture length of nearly 250 km between Rendova and the Woodlark rise.
DE: 1209 Tectonic deformation (6924)
DE: 7230 Seismicity and tectonics (1207, 1217, 1240, 1242)
DE: 7240 Subduction zones (1207, 1219, 1240)
DE: 8150 Plate boundary: general (3040)
DE: 8170 Subduction zone processes (1031, 3060, 3613, 8413)
SC: Tectonophysics [T]
MN: 2007 Fall Meeting