The Lau Basin Ocean Bottom Seismograph Survey was a 3 month deployment
of 30 Ocean Bottom Seismographs (OBS) in the Lau backarc and Tonga forarc
during late 1994. The project is a collaboration between
Douglas Wiens (Washington University) and Leroy Dorman, John Hildebrand, and
Spahr Webb (Scripps Institute of Oceanography). The OBSs were deployed
from the R.V. Melville during September, 1994, and recovered from the
R.V. Moana Wave in January, 1995. The OBS survey took place
during the Southwest Pacific Seismic Experiment (SPaSE), a 2 year deployment of
12 broadband seismographs on the islands of the Tonga-Fiji region.
The goals of the project are to image the upper mantle structure associated with the subducting Tonga slab and the active Lau backarc spreading center.
Station Map
Initial Research Results:
Keith Koper, D.A. Wiens, D. Zhao, L. Dorman, S. Webb,
J. Hildebrand,
Can seismology resolve a metastable olivine wedge in the
Tonga Subduction Zone?, Fall AGU, 1996.
Dapeng Zhao, Y. Xu, D. A. Wiens, L. Dorman, J. Hildebrand, S. Webb,
Depth extent of the Lau back-arc spreading centre and its relationship
to subduction processes, abstract of paper submitted, 1997.
P-wave Tomographic images of the Tonga subduction zone and
Lau backarc, from the submitted paper:
Cross section of the arc at about 18 deg latitude
Map view of velocity variations at 25 km depth
Map view of velocity variations at 140 km depth
Photos of the OBS deployment, showing the equipment
Leroy Dorman deploying one of the ONR OBSs
Spahr Webb and Wayne Crawford along with one of the Webb OBSs
OBSs on the deck of the R.V. Melville, as it sails past the Tonga volcanic island of Late
Comments or questions?? Send email to
doug_at_kermadec.wustl.edu
Latest revision: May 7, 1997
