"Lite Geology" Focuses on Earthquakes

by Rachel Armstrong

SOCORRO, N.M., October 23, 2002-The New Mexico Bureau of Geology and Mineral Resources (NMBGMR) published the most recent issue of its newsletter Lite Geology. The current issue focuses on earthquakes.

The featured article, "Earth Briefs," discusses the importance of using earthquakes for predicting volcanic eruptions. For example, the massive 2001 eruption of Mount Etna, Italy, was preceded by the largest swarm of earthquakes in that area for the 20 years prior. The article goes on to state that these low magnitude earthquakes are caused by magma movement in the Earth's crust, which radiates movement up to the surface.

The article mentions three different varieties of volcanic earthquakes: volcanotectonic, which can not be traced to a body of magma; long-period earthquakes, which are the result of magma migration; and tremors, which are almost always associated with eruptions.

The article also mentions that the magma bodies beneath the Valles caldera, Jemez Mountains, and area around Socorro are being monitored by scientists at New Mexico Tech and Los Alamos National Laboratories. For more information, visit http://www.ees.nmt.edu/Geop/Research_and_Outreach/research.html

The second featured article, "New Mexico Earthquakes: Mid-1800s through 1998," discusses the strengths and frequencies of earthquakes in New Mexico, primarily the area surrounding Socorro, referred to as the Socorro Seismic Anomaly (SSA). "The area within the SSA occupies 1.6% of the total area of the state," the article notes, "but accounts for 37% of the earthquakes of magnitude 2.0 or greater, or 47% of the earthquakes of magnitude 4.5 or greater."

The article also introduces the two different scales for measuring the intensity of earthquakes. The Modified-Mercalli Intensity Scale, commonly used before seismographs, utilizes buildings and other surroundings as pinpoints, and Richter Magnitude measures intensity using seismographs.

A sidebar titled "Earthquake Exercise at Alamogordo, New Mexico" tells about a city-wide exercise that took place in August 2001. The exercise simulated the results of a magnitude seven earthquake, testing a variety of local agencies and their capacity for handling emergencies.

"New Mexico's Most Wanted Minerals" page features sulfur, giving its description, most common uses, formation, location, and other names for the soft mineral.

The "Postcard From the Field" section, titled "Afield, Horseback" tells a story about the author's adventure in the field while mapping the geology of the San Felipe Pueblo on a stormy April day.

Lite Geology, an award-winning quarterly magazine published by the NMBGMR, is devoted to increasing Earth science awareness by showcasing contemporary geological topics, issues, and events in an easily understood, fun-to-read format. It is designed to be less technical than most of the NMBGMR's other publications and is primarily directed toward educators and other members of the public who have an interest in geology and the related Earth sciences. Subscriptions to the magazine are available free of charge for New Mexico residents. Out-of-state subscribers are asked to contribute a $4 per year subscription fee to the NMBGMR to cover the cost of printing and mailing the periodical.

For more information about Lite Geology, or any other NMBGMR publications, write to the Bureau Publications Office, New Mexico Tech, 801 Leroy Place, Socorro, NM 87801, call (505) 835-5410, or visit the Bureau's website at http://geoinfo.nmt.edu.

-NMT-