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SANTA FE – Earthquake professionals attending an annual meeting here were not surprised to find their favorite subject leading national news reports around the country Friday morning.A magnitude 5.2 earthquake that struck southern Illinois at 4:37 MDT was felt throughout the region, but without much damage.“It always happens during these meetings,” said Susan Newman, executive director of the Seismological Society of America (SSA), as a three-day technical and scientific program drew to a close.The U.S. Geological Survey (http://earthquake. usgs.gov) put the tremor in proportion with a fact for the day: “It is estimated that there are 500,000 detectable earthquakes in the world each year. 100,000 of those can be felt, and 100 of them cause damage.”By Friday’s end, some 35,000 people in the Midwest availed themselves of the USGS’ “Did You Feel It?” site to record electronically their individual experiences of the earthquake. Their combined response quickly shaped a picture of a phenomenon that touched at least 15 states. Bill Ellsworth, a geophysicist with the USGS and President of SSA, said most people automatically associate earthquakes with California. But in California, this size of earthquake would have only been felt half the distance away because of the underlying geology, he said.“It’s a reminder that the earthquake problem is national,” he said. “They may not occur as frequently in the Midwest, but the problems can be just as severe because the buildings are more vulnerable.”Ellsworth said Friday’s earthquake in Illinois was in the same tectonic province as the New Madrid seismic dome, an area that was convulsed in 1810-11 by three of the strongest earthquakes in U.S. history and that continues to spawn quakes at a higher frequency than any other area east of the Rocky Mountains.Stuart Nishenko, a senior seismologist with Pacific Gas and Electric and chair of the SSA’s government relations committee, said there are lessons to be learned by these kinds of events.On an individual level, there is the personal reality check.“Do you know where you need to go when it starts shaking and what to do when it stops?” he said. The SSA officers said local governments throughout the region would probably be out looking at damages and some might be considering building code changes and infrastructure upgrades as a result of what they find.Ellsworth said USGS would be releasing its latest national hazards map Monday, updating assessments of seismic risks throughout the country.Los Alamos National Laboratory hosted this year’s conference, in cooperation with New Mexico Institute of Mining and Technology, Sandia National Laboratories and the University of Texas at El Paso.Seismic studies have played and continue to play an important security role in monitoring and evaluating international nuclear tests, short of witnessing the tests or seeing the actual records from the blasts.Among other featured topics were presentations on the Rio Grande Rift, a 35-million year phenomenon that has influenced the creation of New Mexico’s mountains and valley’s along the Rio Grande.Another program looked at the role of seismology in archeological studies and the sometimes over-dramatized use of earthquakes and other natural disasters to explain abrupt changes in cultures and civilizations.A report by LANL researchers Wednesday morning discussed seismic hazards at the lab, an evolving subject that has influenced new construction on the Chemistry and Metallurgy Research Replacement facility.