by George Zamora
SOCORRO, N.M., March 17, 2005 – Marshall Reiter, principal senior geophysicist at the New Mexico Bureau of Geology and Mineral Resources (NMBGMR), is the author of two recently published research papers focusing on extended studies of subsurface temperature measurements taken at field sites at Tomé, N.M. and Arroyo del Coyote near Socorro.
In a recent volume of Pure and Applied Geophysics, Reiter examines how subsurface temperatures are affected by ground-water flow and ground surface temperature changes, and, in turn, how scientific interpretations of ground-water flow and ground surface warming are interactively influencing subsurface temperatures.
“This study looks into how much of the measurable changes in subsurface temperatures can be attributed to each phenomenon,” Reiter says. “That hadn’t been done before, as most geoscientists assumed that changes in subsurface temperatures were affected by changes in surface temperatures, but it’s clear that ground-water flow also influences the subsurface temperature.”
Reiter’s study, titled “Possible Ambiguities in Subsurface Temperature Logs: Consideration of Ground-water Flow and Ground Surface Temperature Change,” uses data from field sites at Tomé and Evain, Canada.
In his second recently published article, Reiter investigates subsurface temperatures associated with the earthquake-producing layer at Arroyo del Coyote, across the Rio Grande from Socorro.
“Subsurface temperatures and crustal strength changes within the seismogenic layer at Arroyo del Coyote in the Socorro seismic area, central Rio Grande rift, New Mexico” reports that upper crustal strength in this area may be much more dependent on in situ temperatures than on in situ stresses found at depths of about five miles.
Reiter’s research paper is featured in the current issue of The Geological Society of America Bulletin.
“Through this study, we have been able to determine that subsurface temperatures may be used to define portions of the crust which may be slightly weaker,” Reiter explains, “and are therefore zones where earthquakes are more likely to occur.”
Arroyo del Coyote is within the Socorro seismic area, Reiter points out, and as such has been the subject of several other geophysical studies over the past 30 years.
“Arroyo del Coyote is a wonderful place for this type of study because earthquake depths and corresponding temperatures at these depths have already been very well determined,” Reiter says.
Reiter has studied subsurface temperatures as part of his ongoing research for 40 years. He has been a geophysicist with New Mexico Tech and the NMBGMR, a research and service division of the university, for more than 35 years.