Allen CV
Seismo Lab
Earth & Planetary
UC Berkeley

Vp and Vs structure of the Yellowstone hot spot from teleseismic tomography: Evidence for an upper-mantle plume

Gregory P. Waite, Robert B. Smith
University of Utah

Richard M Allen
UC Berkeley

J. Geophys. Res. 111, B04303, doi:10.1029/2005JB003867

Download a reprint: WaiteSmithAllenJGR2006.pdf (4Mb)

Abstract. The movement of the lithosphere over a stationary mantle magmatic source, often thought to be a mantle plume, explains key features of the 16 Ma Yellowstone-Snake River Plain volcanic system. However the seismic signature of a Yellowstone plume has remained elusive due to the lack of adequate data. We employ new teleseismic P and S wave traveltime data to develop tomographic images of the Yellowstone hotspot upper mantle. The teleseismic data were recorded with two temporary seismograph arrays deployed in a 500 km by 600 km area centered on Yellowstone. Additional data from nearby regional seismic networks were incorporated into the dataset. The VP and VS models reveal a strong lowvelocity anomaly from ~50 to 200 km directly beneath the Yellowstone caldera and eastern Snake River Plain, as has been imaged in previous studies. Peak anomalies are 2.3% for VP and 5.5% for VS. A weaker, anomaly with a velocity perturbation of up to 1.0% VP and 2.5% VS continues to at least 400 km depth. This anomaly dips 30 from vertical, west-northwest to a location beneath the northern Rocky Mountains. Synthetic and resolution tests confirm this deeper low-velocity anomaly. In addition, a highvelocity anomaly, 1.2% VP and 1.9% VS, is located at ~100 to 250 km depth southeast of Yellowstone. We interpret the low-velocity body as a plume of upwelling hot, and possibly wet rock, from the mantle transition zone that promotes small-scale convection in the upper ~200 km of the mantle and long-lived volcanism.

© Richard M Allen