Accomplishment Based Renewal: Temporal Evolution of Hydrothermal and Volcanic Processes at the East Pacific Rise From Microearthquake Data

Recent work has shown that micro earthquake studies can contribute significantly to understanding a variety of processes that occur on mid ocean ridges. From October 2003 to January 2007 an array of Ocean Bottom Seismometers (OBSs) recorded ~320,000 microearthquakes near 9°50?N on the East Pacific Rise (EPR). To date this project has been very successful; it has led to several important discoveries, and it has produced 10 scientific papers, two of which have appeared in the most prestigious journals, Science and Nature. Tolstoy?s work has also been featured in the NSF annual report to Congress. This project has also spawned research in related disciplines. The EPR OBS experiment recorded around two orders of magnitude more earthquakes than had been expected and renewal funding will enable continued analysis of these data; specifically, studying temporal trends in the structures inferred from the earthquakes; analyzing source processes, focal mechanisms and variations in the stress field before, during and after the eruption; examining data for seismic evidence that eruptive activity occurred in the 6 months prior to the main seismic crisis (January 22, 2006) as implied by radiometric dating. Among the broader impacts of this project are a vigorous public outreach program, support for a graduate student and support for a highly productive female investigator.