Seismological Research Letters; May 2008; v. 79; no. 3;
p. 384-392; DOI: 10.1785/gssrl.79.3.384
© 2008 Seismological Society of America
Upper Mantle Heterogeneity beneath North America from Travel Time Tomography with Global and USArray Transportable Array Data
Scott Burdick1,
Chang Li1,
Vladik Martynov2,
Trilby Cox2,
Jennifer Eakins2,
Taimi Mulder2,
Luciana Astiz2,
Frank L. Vernon2,
Gary L. Pavlis3, and
Robert D. van der Hilst1
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INTRODUCTION
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The large volume of broadband waveforms that are being acquired by USArray
(http://www.iris.edu/USArray/),
the seismology component of the national Earth science program EarthScope
(http://www.earthscope.org/),
offer unique opportunities for seismic imaging. Constraining structures on a
range of length scales and understanding their physical and chemical causes is
a prerequisite for understanding the relationship between near surface and
deeper mantle processes. One can expect that, eventually, full wave tomography
(e.g., De Hoop and van der Hilst
2005; De Hoop et al.
2006; Tromp et al.
2005; Zhao and Jordan
2006) with broadband USArray waveforms will produce superior
insight into the structure of the mantle beneath North America, but linearized
tomographic inversion of phase arrival time data readily yields exciting
results in regions where data from dense seismograph networks is available. We
will use travel times from the transportable component of USArray, hereinafter
referred to as USArrayTA, and from other sources, such as the EHB data base
(Engdahl et al. 1998),
to constrain 3-D mantle heterogeneity beneath North America.
Tomographic images based on USArrayTA data will help us understand
first-order geological structure of and processes in the mantle beneath North
America. Examples include, but are not restricted to: 1) the transition from
the stable continental lithosphere at the center of the North American
continent to the tectonically active domains farther west, 2) the Cascadian
subduction system, 3) the Yellowstone hotspot, and 4) the relationship between
current and past episodes of subduction and upper mantle upwellings and
processes deeper in the mantle. Before the advent of USArrayTA, insight into
mantle structure beneath the western United States was obtained either from
pieced-together regional P-wave studies (e.g.,
figure 1A, after
Dueker et al. 2001) or
from global travel time . . . [Full Text of this Article]
Department of Earth, Atmospheric, and Planetary
Sciences
Massachusetts Institute of Technology
77 Massachusetts Ave.
54-513
Cambridge, Massachusetts 02139
USA
sburdick@mit.edu
(S.
B.)
Copyright © 2008 by Seismological Society of America