Marine geology/geophysics/tectonics

Using a range of superb facilities, the Joint Program faculty and staff study a range of problems in marine geophysics and tectonics, including:

• Seafloor volcanic processes—At mid-ocean ridges magmatic, tectonic, and hydrothermal processes combine to form the oceanic crust. The surface expression of this complex system is distinctive sea-floor topography, the characteristics of which vary from ridge to ridge. Researchers are currently studying volcanic processes at mid-ocean ridges from their inception in the mantle to their manifestations in the biosphere and water column, as well as subaerial volcanic rift zones and their submarine extensions, most recently in the Galapagos Islands and Hawaii.
• Ocean crustal structure—Despite extensive studies of mid-ocean ridges over the past three decades, comparatively little is known about the structure of the ocean crust. The thickness of oceanic crust provides key constraints on magma supply variations while knowledge of the presence, depth and dimensions of crustal magma bodies is essential for understanding the volcanic history of the ridge and axial hydothermal systems. Researchers use geophysical techniques to study ocean crustal structure along many of the world's major spreading centers.
• Faulting and tectonics—Active faulting occurs both along oceanic plate boundaries and in the interior of oceanic plates, causing major earthquakes at subduction zones, transform faults, and mid-ocean ridges. Current projects apply earthquake seismology, rock mechanics, geology, geodesy, and geodynamics to investigate stresses and rheology of the oceanic lithosphere, causes and mechanisms of oceanic earthquakes, fault mechanics, and the coupling between tectonics and fluid flows in the oceanic crust.
• Upper mantle dynamics—Many models of flow in the upper mantle beneath the oceans have been developed since the discovery of plate tectonics. Researchers currently use constraints from petrology, geochemistry and theoretical modeling of geodynamic processes, as well as the application of broadband seismic techniques and natural source magnetotelluric methods in the oceans, to test and refine models of mantle flow.
• Ocean-continent interactions—The geologic evolution of the continents is known to have a profound effect on the global ocean. Coupling between the solid earth and its atmosphere and the oceans is manifested as the opening and closing of straits or "gateways" between major ocean basins, and as disruption of atmospheric circulation by the uplift of mountains. These interrelationships are most dramatic in the Himalayas and Tibetan Plateau.

Faculty: Clark Burchfiel (EAPS, MIT), Brian Evans (EAPS, MIT), John Collins (G&G), Henry Dick (G&G), Rob Evans (G&G), Tom Herring (EAPS, MIT), Brad Hager (EAPS, MIT), Jian Lin (G&G), David Mohrig (EAPS, MIT), Rob Sohn (G&G), Leigh Royden (EAPS, MIT), Maurice Tivey (G&G), Maria Zuber (EAPS, MIT), Dan Lizarralde (G&G), Yang Liao (G&G)