February 2002 Meeting Abstract
The topic for presentation and discussion will be: "20,000 Leagues Under the Sea: Exploring Submarine Volcanoes on the East Pacific Rise" presented by Dr. Tracy K.P. Gregg, Assistant Professor, SUNY Buffalo.
The vast majority of Earth's active volcanoes are located on the ocean floor along the global mid-ocean ridge (MOR) system. MORs form a global chain of volcanism approximately 70,000 km long that encircles the globe like the seams of a baseball. Although an active MOR eruption has not yet been observed, volcanism at MORs play a vital role in shaping the surface of our planet. Increased activity at MORs during the Cretaceous period, for example, has been linked to sea-level rise and dinosaur extinction. Every MOR eruption releases heat and chemicals into the oceans; current research has been focussing on how these fluxes may affect the global temperature and composition of the oceans to determine the role MOR activity plays in climate change. To constrain the affects of MOR eruptions, it is vital to determine how often the eruptions, how long they last, and how large they are. This is, however, difficult and expensive work.
Dr. Gregg has been studying volcanic eruptions along the East Pacific Rise (EPR) and the Juan de Fuca Ridge to address these issues. The EPR, between 9°30'N and 9° 53'N, is a fast spreading center, with a full spreading rate of approximately 9 - 10 cm/year and is defined by a broad rise (~200 m high and 1-2 km wide) capped by a narrow (<150 m), shallow (<8 m) linear collapse trough. The floor of the trough contains the primary eruptive fissures, and most volcanic eruptions originate here.
In 1991, an eruption filled much of the axial summit collapse trough, and lava spilled out of the trough and flowed off-axis for a few hundred meters. Because the region was visited soon after the event, this eruption is used as a touchstone for identifying young lava flows elsewhere along Earth's MOR system. Multiple tools have been used to study this region, including rock-coring, dredging, remotely operated vehicles, and the Deep Submergence Vehicle Alvin.
DSV Alvin is owned by the U.S. Navy but is operated by Woods Hole Oceanographic Institution. It can dive to depths as great as 4500 m, and can remain on the ocean floor for about 5 hours before returning to the surface. With each dive, Alvin takes three people (usually 1 pilot and 2 scientists) to the ocean floor to learn more about this mysterious realm.
Dr. Gregg holds a Bachelor's degree from Brown University, in Rhode Island and a Ph.D. from Arizona State University at Tempe, Arizona. She has been an Assistant Professor for the Department of Geology at UB since 1998. She is also an Adjunct Assistant Scientist at Woods Hole Oceanographic Institution and she is serving as the first Vice-Chair of the Planetary Geology Division of the Geological Society of America. Her research interests are mainly on marine volcanology and planetary geology. She is very active in various scientific comities and panels including the Planetary Geology Division of the Geological Society of America (GSA), the Planetary Geosciences Student Paper Award Judging Panel, and the NASA Planetary Geology and Geophysics Planetary Mapping Standards Panel. Dr. Gregg has over 20 publications in a number of scientific journals and has co chaired and organized five annual East Coast Volcanology Gatherings and two theme sessions for GSA and served in the organizing committees for two Lunar and Planetary Science Conferences.
By relying heavily on Alvin, Dr. Gregg was able to get the first quantitative analyses of the mysterious eruptions along the EPR. Although most of Earth's MOR system remains unexplored, we are at least beginning to understand small, significant parts of it.