1. University of Utah Seismograph Stations, University of Utah, Salt Lake City, Utah, U.S.A.
2. Montana Bureau of Mines and Geology, Montana Technological University, Butte, Montana, U.S.A.
3. Arizona Geological Survey, University of Arizona, Tucson, Arizona, U.S.A.
4. New Mexico Bureau of Geology and Mineral Resources, Socorro, New Mexico, U.S.A.
5. Idaho National Laboratory, Idaho Falls, Idaho, U.S.A.
6. New Mexico Institute of Mining and Technology, Socorro, New Mexico, U.S.A.
7. Colorado Geological Survey, Boulder, Colorado, U.S.A.