Education

Ph.D., 2001, University of California, Santa Barbara (Geological Sciences)

B.S., 1994, University of California, Davis (Geology)

Complete CV >>

Research Areas

Marine Geology and Geophysics; Environmental Geophysics; Seafloor Mapping; Terrain modeling and GIS

On-going and Recent Projects

Anatomy of an Overlapping Spreading Center, East Pacific Rise 9º North

An overarching goal in the study of mid-ocean ridges is to understand the flow of magma from the deep mantle source to the eruption of lava on the seafloor. An excellent opportunity to advance our understanding of these linkages has emerged through the recent acquisition of detailed information on the distribution of melt at depth beneath the 9°03’N Overlapping Spreading Center on the East Pacific Rise.  The main hypothesis of this project is that variations in the depth and dimensions of the melt sills and variations in melt distribution in the upper mantle will lead to identifiable characteristics in the spatial distribution of eruption sites, distinct lava compositions, and hydrothermal activity.   More on cruise website >>

Volcanic Eruption of the East Pacific Rise in 2006

The 2006 eruption of the East Pacific Rise presents an unprecedented opportunity to gain insight into the eruptive processes at mid-ocean ridges.  This is the first eruption of a mid-ocean ridge with comprehensive meter-scale seafloor bathymetry and side-scan imagery available from prior to the eruption. The objectives of this proposal are to assess the along and across-axis extent of the eruption, calculate the volume of the eruption products, and measure changes in seafloor morphology due to the eruption.  Knowing where and how much lava is emplaced during an eruption is crucial to ultimately understanding the eruption process. Direct comparison of DSL-120 side-scan and phase bathymetry from before and after the eruption will detect ~2 m or greater changes in seafloor topography, identifying lava depocenters and eruptive volumes.

Hydrothermal Response to Magma Supply and Crustal Thickness on the Galapagos Spreading Center

The Galapagos Spreading Center is an ideal natural experiment on how magma supply and crustal thickness affect the nature, abundance, and distribution of ridge crest hydrothermal activity, and interactions between hydrothermal, volcanic, tectonic, and biological processes.  In Dec 2005 - Jan 2006, we surveyed the ridge crest with sonar, water-column, and video along the GSC, 89.5ºW-94ºW.  We discovered the first black smokers on the GSC and shed new light on how excess heat from mantle plumes is dissipated along hotspot-influenced spreading centers.  This cruise was featured on the NOAA Ocean Explorer website >>

Western Aleutian Volcanic Expedition (WAVE)

Coastal Groundwater Hydrogeophysics

Knowledge of groundwater dynamics in coastal settings is key to understanding submarine groundwater discharge, saltwater intrusion into freshwater aquifers, and chemical exchange between seawater and freshwater.  Electrical resistivity is used in combination with piezometers to delineate the freshwater lens and monitor the fresh-saline water interface.  Project areas include a barrier island system at Sapelo Island, GA and a forest-saltmarsh transect at North Inlet, SC.   The hydrogeophysics is done in collaboration with the hydrological modeling of Prof. Alicia Wilson at USC.

Global Rates and Volumes of Volcanism on Earth

A global compilation of 170 time-averaged volumetric volcanic output rates are evaluated in terms of composition and petro-tectonic setting to advance the understanding of long-term rates of magma generation and eruption on Earth.  Repose period between successive eruptions and intrusive:extrusive ratios were compiled for selected volcanic centers where long-term (>10,000 yr) data were available. Findings include that more silicic volcanic centers, rhyolites and andesites, have a more limited range of eruption rates than basalts. This trend is also seen in the difference between oceanic and continental settings, as eruptions on oceanic crust tend to be predominately basaltic.  However, we have found no systematic evidence linking increased intrusive:extrusive ratios with lower volcanic rates.   >> Download tables of volcanic rates and volumes >>

Graduate Students

Seafloor Mapping Lab @ Carolina

This lab contains facilities for data collection and post-processing of a wide variety of geophysical data.  Our computer software resources include ArcGIS, ENVI, ERDAS Imagine, Matlab, Chesapeake Technology's Sonar.Wiz MAP, Kingdom Suite, and Generic Mapping Tools and MB-system.

Geophysical Instruments   (please contact Dr. White if you are interested in using them on your project)

• Imagenex Yellowfin side-scan sonar 
• Stratabox Sub-Bottom Profiler
• MiniRes Resistivity/IP Meter
• GEM 19TG Gradient Magnetometer
• AGI SuperSting R1 28-channel Resistivity/IP with waterproof cable