To determine whether the San Andreas Fault is moving with the tremors, scientists with the San Andreas Fault Observatory at Depth (SAFOD) are installing instruments to measure the tremors' activity. Located near Parkfield, Calif., SAFOD is part of the EarthScope Project, an effort to study the North American continent's geology.
"Unlike the sharp jolt of an earthquake, tremors within Earth's crust emerge slowly, rumbling for longer periods of time," said Kaye Shedlock, program director for EarthScope at the National Science Foundation (NSF), which funds the project. "Although not in this case, tremors are usually produced by magma moving in cracks or other conduits beneath a volcano."
The rumblings are the first recordings of non-volcanic tremors in a deep borehole, providing scientists with data to better understand such mysterious underground movements.
The results will help geologists understand whether the deeply buried rocks of the San Andreas Fault - which are derived from an ancient subduction zone - behave in a similar way to the rocks of the Cascadia Subduction Zone, still active today.
"In the Cascadia Subduction Zone off the Pacific Northwest, for example, tremors are associated with the slow slip of the undersea Juan de Fuca tectonic plate as it submerges beneath the North American tectonic plate," said Greg van der Vink, EarthScope facility project director.
The National Science Foundation (NSF) is an independent federal agency that supports fundamental research and education across all fields of science and engineering, with an annual budget of $5.58 billion. NSF funds reach all 50 states through grants to nearly 1,700 universities and institutions. Each year, NSF receives about 40,000 competitive requests for funding, and makes nearly 10,000 new funding awards. The NSF also awards over $400 million in professional and service contracts yearly.
Receive official NSF news electronically through the e-mail delivery and notification system, MyNSF (formerly the Custom News Service). To subscribe, visit http://www.nsf.gov/mynsf/ and fill in the information under "new users".
Useful NSF Web Sites:
NSF Home Page: http://www.nsf.gov
NSF News: http://www.nsf.gov/news/
For the News Media: http://www.nsf.gov/news/newsroom.jsp
Science and Engineering Statistics: http://www.nsf.gov/statistics/
Awards Searches: http://www.nsf.gov/awardsearch/
Last reviewed: By John M. Grohol, Psy.D. on 21 Feb 2009
Published on PsychCentral.com. All rights reserved.