A primary research focus of my group in recent decades has been marine seismology. The scale of these studies has varied by two orders of magnitude from detailed studies of ocean ridge crest structure and hydrothermal systems to regional studies of upper mantle structure.

Hydrothermal systems mine heat from the hot rock. The rock contracts as it is cooled causing a multitude of small earthquakes. We are able to track the active regions by locating these small earthquakes very precisely using double difference methods. We have show that these earthquakes can perturb the hydrothermal systems through changing the pathways of fluid flow.  Our tomographic studies of ridge crest structure using active source methods have revealed an evolution in seismic properties in the shallow crust with age of the crust.

Regional scale OBS experiments have provided the first detailed measurements of the structure in the oceanic upper mantle near ridge crests (MELT, TOES, GLIMPSE) and above subducting slabs (LABATTS). Studies of surface wave propagation have allowed us to map variations in upper mantle properties on the regional scale.  The ELSC seismic experiment will be the next experiment to focus on the structure of back arc basin. This experiment is much larger than any previous OBS experiment and it should provide a very detailed tomographic image of the structures in the mantle wedge above the slab and beneath the back arc.  Our current understanding of the processes associated with back arc spreading and the effects of volatiles on mantle melting is very limited by a lack of good images in these regions.

Marine Seismology is its myriad forms will continue to be an important focus for my research group.  We have just begun construction of 30 ocean bottom seismometers for deployment across the Cascadia margin (Washington, Oregon, Northern California).