HR: 0800h
AN: G51C-0621    [Abstracts]
TI: Surface Deformation from ALOS Interferometry Related to the July 2006 Seismic Crisis and Dike Intrusion on Central New Britain Island, Papua New Guinea
AU: * Wicks, C W
EM: cwicks@usgs.gov
AF: U. S. Geological Survey, MS 977 345 Middlefield Rd, Menlo Park, CA 94025, United States
AU: White, R
EM: rwhite@usgs.gov
AF: U. S. Geological Survey, MS 977 345 Middlefield Rd, Menlo Park, CA 94025, United States
AU: Patia, H
EM: hguria@global.net.pg
AF: Rabaul Volcanological Observatory, P.O. Box 386, Rabaul, 1, Papua New Guinea
AU: Collins, C
EM: Clive.Collins@ga.gov.au
AF: Geoscience Australia, GPS Box 378, Canberra, 2601, Australia
AU: Johnson, W
EM: wallyjohnson@grapevine.com.au
AF: Geoscience Australia, GPS Box 378, Canberra, 2601, Australia
AU: Yarai, H
EM: yarai@gsi.go.jp
AF: Geographical Survey Institute, Kitasato-1 Tsukuba, Ibaraki, 305-0811, Japan
AB: In July of 2006 a seismic swarm struck near the Sulu volcanic range on the north coast of central New Britain Island, in Papua New Guinea. In the global Centroid Moment Tensor (CMT) catalog (www.globalcmt.org) a total of eighteen earthquakes were large enough for CMT solutions to be determined. The magnitudes of earthquakes with CMT solutions ranged from Mw 4.8 to 5.2 until July 19 when the two largest earthquakes in the swarm (Mw 5.9 and 6.4) occurred. These were also the last two earthquakes in the swarm large enough for a CMT solution to be determined. L-band radar interferometry data from Japan's Daichi ALOS satellite captured the surface deformation associated with the seismic swarm. Modeling of over 1 m of peak to peak range change deformation is consistent with intrusion of about 1 km³3 of magma in a near-vertical dike with over 10 m of opening. The subduction zone beneath the study area is very dynamic, with the Solomon Sea plate subducting under the South Bismarck plate at more than 130 mm/year. Also, the volcanics in the Sulu range are some of the most elementally depleted arc volcanics on Earth. In our interpretation the dike intrusion proceeded in a WSW direction from under the Sulu volcanic range until it intersected a pre-existing fault upon which the July 19 Mw 5.9 and 6.4 strike-slip earthquakes occurred. Aftershock data recorded after July 19 with support by Geoscience Australia displays a sharp linear cutoff that aligns with the favored NW striking fault plane of the two July 19 earthquakes.
DE: 0370 Volcanic effects (8409)
DE: 0933 Remote sensing
DE: 1240 Satellite geodesy: results (6929, 7215, 7230, 7240)
DE: 8413 Subduction zone processes (1031, 3060, 3613, 8170)
DE: 8434 Magma migration and fragmentation
SC: Geodesy [G]
MN: 2007 Fall Meeting