About 1,000 Earthquakes Shook Arizona in Recent Three-Year Period, ASU Researchers Report

Arizona shook from the tremors of nearly 1,000 earthquakes between 2006 and 2009, according to data recently published by Arizona State University researchers.

New data from a National Science Foundation program recorded the seismic activity, which has scientists excited because of the unexpected frequency of quakes and the fact that they were spread across areas of the state previously thought to be geologically quieter.

The reason cities aren't laying in ruins, as you could have guessed, is because most those quakes were micro-sized.

In the mid-90s, ASU researchers used equipment on loan from EarthScope's "US Array," a "continental-scale seismic observatory designed to provide a foundation for integrated studies of continental lithosphere and deep Earth structure." EarthScope's Web site says the program consists of 400 seismometers being stationed across the country.

Arizona has long been though to have earthquakes, but only rarely. The EarthScope study has debunked that "myth," says ASU.

Jeffrey Lockridge, a graduate student in ASU's School of Earth and Space Exploration who was the project's lead researcher, published his team's results in the August 2012 issue of the Bulletin of the Seismological Society of America.

Most Arizona quakes occur in north-central Arizona. A United States Geological Survey Web site describes one quake near Williams on August 18, 1912, that ripped a "50-mile-long crack in the earth north of the San Francisco Range."

Lockridge told ASU the findings of earthquakes in other areas of the state was significant, but "not necessarily surprising" because it was the first time many of those areas had been scoped out with seismometers. Still, "I expected to find some earthquakes outside of north-central Arizona, where the most and largest events had previously been recorded, just not quite so many in other areas of the state."

ASU says Lockridge is hard at work on a study to be published next year that focuses on earthquakes near Roosevelt Lake.

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Ray Stern has worked as a newspaper reporter in Arizona for more than two decades. He's won numerous awards for his reporting, including the Arizona Press Club's Don Bolles Award for Investigative Journalism.