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Research Interests

Allan R. Sanford, Emeritus Professor of Geophysics

Lying at a depth of 19 km beneath the Socorro area of the Rio Grande rift is an extensive (more than 2000 square km), thin (~150 meters), horizontal layer of molten rock. The existence of this sill of magma, which was discovered through studies of microearthquake reflection phases, makes this region a truly unusual and important target for geophysical investigations.

Surface uplift coincident with the location of the magma body is occurring at an average rate of 1.8 millimeters/year and indicates that injection of magma is currently taking place at mid-crustal levels. The stresses induced by this inflation as well as upward migration of small quantities of magma into the upper crust are producing an abnormally high level of seismic activity - the highest observed anywhere along the rift and in New Mexico and West Texas. My graduate students and I use recordings of these earthquakes, primarily the very numerous microearthquakes, to determine the location and characteristics of magma bodies and the physical properties of the crustal rocks, for example their velocities, attenuation coefficients, and state of stress.

We also have research interests on the seismo-tectonics of the Rio Grande rift. New Mexico Tech, in collaboration with the Los Alamos National Laboratory and the U.S. Geological Survey, has developed an extensive instrumental data set on earthquakes which have occurred in or bordering the rift since 1960. Much has been learned about the spatial and temporal behavior of rift seismicity from this data. However, much remains to be done, particularly in those regions where information is sufficiently detailed to examine relations between seismicity, detachment surfaces, young surface ruptures, and injection of magma.

The Socorro Midcrustal Magma Body

Created: ( Wednesday, 21 September 2011 10:37 )
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