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Wells, Nevada Earthquake February 21, 2008 A 6.0 magnitude earthquake strikes the northeastern edge of the Basin and Range Wells, Nevada Earthquake Basin and Range Why Nevada? The earthquake occurred near the edge of the Basin and Range province. Over the Basin and Range province the continent is actively rifting. Parks and Plates ©2005 Robert J. Lillie Wells, Nevada Earthquake Basin and Range Tectonics Continental Rift Features Hot Asthenosphere Parks and Plates ©2005 Robert J. Lillie Wells, Nevada Earthquake Basin and Range Tectonics Continental Rift Features Parks and Plates ©2005 Robert J. Lillie Wells, Nevada Earthquake Historical Seismicity near Wells, Nevada Wells, Nevada Earthquake The earthquake occurred near the center of more than 400 recording seismometers. http://eqseis.geosc.psu.edu/~ cammon/QA/wellsNV21Feb2008.html Wells, Nevada Earthquake Seismic Data Wells, Nevada Earthquake Strainmeters Wells, Nevada Earthquake Strainmeters Wells, Nevada Earthquake Horizontal Displacement The actual source mechanism (USGS) The modeled source mechanism (Hammond and Kreemer, University of Nevada Reno) Wells, Nevada Earthquake Geodetic Strain Geodetic Strain Rates in Great Basin Map of contours of the rate of strain accumulation. The redder the colors the more rapidly the crust is accumulating strain. This strain is generally released in future earthquakes. The map is produced by interpolation of horizontal motions measured at hundreds of points using GPS. The Wells earthquake (star) happened in an area where the GPS measurements indicate the same amount of strain accumulation as within the stable continent. Source: C. Kreemer, Nevada Geodetic Laboratory, UNR. Wells, Nevada Earthquake EarthScope Why are there so many geophysical instruments in the West, anyway? • They are a part of EarthScope - a national earth science experiment. • EarthScope is: • Exploring the structure and evolution of the North American continent. • Understanding the processes that cause earthquakes and volcanic eruptions. Wells, Nevada Earthquake EarthScope What instruments does EarthScope have? Drilling into the San Andreas Fault Portable Seismometers Permanent Seismometers GPS Stations Borehole Strainmeters QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. Long-baseline Laser Strainmeters Wells, Nevada Earthquake EarthScope Partners
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