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Michael Creech
Mathematics/Geological Science

Douglas Toomey, Mentor

Mechanisms for Seismicity on the southern Endeavor Segment

The mid-ocean ridge is the longest continuous mountain chain on earth and is the source for the approximately 20 cubic kilometers of oceanic lithosphere generated each year. Mid-ocean ridges are classified by spreading rates into three groups: fast, intermediate, and slow. Fast spreading ridges are dominated predominantly by magmatic volcanism, whereas slow spreading ridges are predominantly governed by tectonic rifting. Intermediate spreading ridges have yet to be classified by either of these two processes. The Juan de Fuca ridge is an intermediate spreading ridge that exhibits both magmatic and tectonic features. Earthquake swarms are indicative of both of these processes. Using data from the Endeavor seismic array, the swarm on May 10, 2004 can be classified as either magmatic or tectonic. A large magnitude earthquake followed by aftershocks will identify a tectonic event, and a magmatic event will reveal a migration pattern in the seismic record.