Wells, Nevada EarthquakeFebruary 21, 2008

A 6.0 magnitude earthquake strikes the

northeastern edge of the Basin and Range

Wells, Nevada Earthquake

Basin and Range

Parks and Plates©2005 Robert J. Lillie

The earthquake

occurred near the edge

of the Basin and Range

province. Over the

Basin and Range

province the continent

is actively rifting.

Why Nevada?

Continental Rift Features

Parks and Plates©2005 Robert J. Lillie

Hot Asthenosphere

Wells, Nevada Earthquake

Basin and Range Tectonics

Parks and Plates©2005 Robert J. Lillie

Wells, Nevada Earthquake

Basin and Range Tectonics

Continental Rift Features

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/wellsNV-21Feb2008.html

Wells, Nevada Earthquake

Seismic Data

Wells, Nevada Earthquake

Strainmeters

Wells, Nevada Earthquake

Strainmeters

(Hammond and Kreemer, University of Nevada Reno)

Wells, Nevada Earthquake

Horizontal Displacement

The actual source mechanism

(USGS)

The modeled source mechanism

Source: C. Kreemer, Nevada Geodetic Laboratory, UNR.

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.

Geodetic Strain Rates in Great Basin

Wells, Nevada Earthquake

Geodetic Strain

• 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

Why are there so many geophysical instruments in the West, anyway?

What instruments does EarthScope have?

Wells, Nevada Earthquake

EarthScope

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are needed to see this picture.

Drilling into the San Andreas Fault

Portable Seismometers

Permanent Seismometers

GPS Stations

Borehole Strainmeters

Long-baseline Laser Strainmeters

Wells, Nevada Earthquake

EarthScope Partners