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Imaging and discovery from USArray and EarthScope

Unprecedented dense deployment of EarthScope USArray Transportable Array, Flexible Array and Magnetotelluric instruments is providing data that are being used to develop a new generation of high-resolution Earth models and understanding of structure and processes. Fresh observations:

• Earthscope Gradiometry: Charles A. Langston, et al., will discuss a new tool for understanding seismic waves by taking a snapshot of how seismic waves propagate across the United States. Rather than evaluate how the ground shakes as seismic waves pass through, this tool looks directly at the seismic wave and how it behaves. Using a newly developed theory, this research offers an entirely new way to consider seismic waves, opening new fields of study.

• Evolution and Effects on the Western U.S. of the Yellowstone Hotspot and Mantle Plume: The Yellowstone hotspot resulted from interaction of a mantle plume with the overriding N. America plate producing a ~800-km wide, ~300-m high topographic swell centered on Yellowstone and produced the 800 km-long, 17 Ma Yellowstone-Snake River Plain volcanic field. Scientists have observed an unprecedented episode of caldera uplift, up to 7 cm/yr from 2004-2008 -- an accelerated rate of 2-3 times the rate recorded in historic time that is consistent with magma intrusion rate of 0.1 km^^3/year, or tens of times larger than the average annual rate of mapped uplift of the caldera. Extrapolating the location of the Yellowstone mantle-source southwestward to an initial position at 17 million years ago beneath eastern Oregon and the southern LIP Columbia Plateau basalt field, suggests a common mantle source for these features. Robert Smith, et al., suggest that the original plume ascended vertically behind the subducting Juan de Fuca plate, but at ~12 Ma became entrained in faster mantle flow beneath continental lithosphere and became tilted into its present configuration.

Location: DeAnza Ballroom II, Friday, April 10, 2009, 1:30 p.m.

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