Abstract
We computed a reflectivity image for the Earth beneath the Jemez volcanic
field, New Mexico, using a novel adaptation of petroleum exploration
seismic imaging. This image was obtained by applying the Kirchhoff
wave field imaging method to digitally recorded teleseismic data.
The volume imaged has a lateral extent of 30 km, extends to 45 km
depth, and lies beneath the Valles caldera, to the west of Los Alamos,
New Mexico. The derived picture of the Earth is a three-dimensional
(3-D) map of the locations of impedance changes within the crust
and upper mantle below the Jemez volcanic field, with a spatial resolution
on the order of a kilometer. Significant features seen in the image
include the base of the caldera fill; several reflectors in the crust
we interpret to be associated with intrusions coming from the mantle
and/or other crystallized chambers such as a low-velocity zone seen
in the tomographic image; two strong reflectors coincident with the
crust-mantle interface, and a zone of layered reflections at the
base of the crust which may be basaltic underplating. This method
proved to be a powerful tool for imaging the Earth's crust and mantle
when combined with other methods, such as tomography.
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