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JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 111, B04303, doi:10.1029/2005JB003867, 2006

VP and VS structure of the Yellowstone hot spot from teleseismic tomography: Evidence for an upper mantle plume

Gregory P. Waite

Department of Geology and Geophysics, University of Utah, Salt Lake City, Utah, USA


Robert B. Smith

Department of Geology and Geophysics, University of Utah, Salt Lake City, Utah, USA


Richard M. Allen

Seismological Laboratory, Department Earth and Planetary Science, University of California, Berkeley, California, USA


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 because of the lack of adequate data. We employ new teleseismic P and S wave traveltime data to develop tomographic images of the Yellowstone hot spot 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 data set. The V P and V S models reveal a strong low-velocity 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 V P and −5.5% for V S . A weaker, anomaly with a velocity perturbation of up to −1.0% V P and −2.5% V S continues to at least 400 km depth. This anomaly dips 30° from vertical, west-northwest to a location beneath the northern Rocky Mountains. 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. A high-velocity anomaly, 1.2% V P and 1.9% V S , is located at ∼100 to 250 km depth southeast of Yellowstone and may represent a downwelling of colder, denser mantle material.

Received 5 June 2005; accepted 28 December 2005; published 13 April 2006.

Keywords: Yellowstone; tomography; plume.

Index Terms: 7203 Seismology: Body waves; 7208 Seismology: Mantle (1212, 1213, 8124); 7270 Seismology: Tomography (6982, 8180).

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Citation: Waite, G. P., R. B. Smith, and R. M. Allen (2006), VP and VS structure of the Yellowstone hot spot from teleseismic tomography: Evidence for an upper mantle plume, J. Geophys. Res., 111, B04303, doi:10.1029/2005JB003867.