Spahr C. Webb

Jerome M. Paros/Lamont Research Professor of Observational Physics
Lamont-Doherty Earth Observatory
Seismology Geology and Tectonophysics
Adjunct Professor
Earth and Environmental Sciences
205 Seismology
61 Route 9W - PO Box 1000
Palisades
NY
10964-8000
US
Phone: 
(845) 365-8439
Fax: 
(845) 365-8896
Fields of interest: 
Marine Seismology, Ocean Mantle Dynamics, Marine EM.

It was evident to me early in my undergraduate career that Earth Science majors had more fun than Physics majors. Better to wander the oceans or deserts than the corridors of some basement lab. Now several times each year I head out across the oceans to toss oceanographic gear into the abyss. Our understanding of the Earth and oceans is primarily driven by improved methods of observation. For this reason, the development of new sensors and techniques has been at the core of my group's efforts.

My current work is primarily in marine geophysics and seismology. We have built a large fleet of ocean bottom seismometers (OBS) to record signals from earthquakes during year long deployments on the deep sea floor. We measure the perturbations to seismic waves from structures within the Earth to study the dynamics of the mantle and crust. The oceanic mantle is the key to understanding the driving forces of plate tectonics including convective processes, the fate of subducting slabs, Earth's hotspots (of which Hawaii and Iceland are the best examples), and the supply of magma to form the oceanic crust beneath ridge crests. We also study the oceanic crust using tomographic methods and man made sources. Tectonic and hydrothermal processes produce earthquakes detected by OBSs and we have even tracked animals within pods of migrating whales using whale song recorded at the seafloor. Other recent work includes mapping magnetic fields to probe temperatures within ridge crest hydrothermal systems and seafloor deformation under wave loading to study magma beneath ridge crests.  Pressure gauges deployed in 2007 are monitoring vertical movements of the seafloor caused by volcanism or the movement of magma.

Education
List of degrees from highest to lowest:
Ph.D.
U.C. San Diego
1984
Bachelor of Science
M.I.T.
1978
Selected Publications: 
Crustal structure beneath the gravity lineations in the Gravity Lineations, Intraplate Melting, Petrologic and Seismic Expedition (GLIMPSE) study area from seismic refraction data, Holmes, R. C.; Webb, S. C.; Forsyth, D. W. , Journal of Geophysical Research-Solid Earth, Jul 26, Volume 112, Issue B7, p.-, (2007), Doi 10.1029/2006jb004685

The Earth's 'hum' is driven by ocean waves over the continental shelves, Webb, S. C. , Nature, Feb 15, Volume 445, Issue 7129, p.754-756, (2007), Doi 10.1038/Nature05536

Rayleigh wave tomography beneath intraplate volcanic ridges in the South Pacific, Weeraratne, D. S.; Forsyth, D. W.; Yang, Y. J.; Webb, S. C. , Journal of Geophysical Research-Solid Earth, Jun 12, Volume 112, Issue B6, p.-, (2007), Doi 10.1029/2006jb004403

Upper mantle structure beneath the eastern Pacific Ocean ridges, Gu, Y. J.; Webb, S. C.; Lerner-Lam, A.; Gaherty, J. B. , Journal of Geophysical Research-Solid Earth, Jun 11, Volume 110, Issue B6, p.-, (2005), Doi 10.1029/2004jb003381

Broad seismology and noise under the ocean, Webb, S.C. , Rev. of Geophysics, Volume 36, p.105-142, (1998)

Seismic, thermal, and chemical evidence for a propagating hydrothermal cracking event on the East Pacific Rise, (9° 50'N), Sohn, R. A.; Fornari, D. J.; VonDamm, K. L.; Hildebrand, J. A.; Webb, S.C. , Nature, Volume 396, p.159-161, (1998)