Hi All. Looks like the “Eastern California Shear Zone” (ECSZ) is back in the news again. It’s still a head scratchier as always. No one is sure what to make of it and why it behaves the way it does. Of course my favorite “The Walker Lane Belt” is still as controversial as ever. Take Care…Don in creepy town

Public release date: 17-Oct-2005
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Contact: A'ndrea Elyse Messer
aem1@psu.edu
814-865-9481
Penn State

Eastern California shear zone puzzles seismologists

“Residents and seismologists in Northern California focus on the San Andreas Fault, but a Penn State researcher thinks more questions should be asked about the Eastern California Shear Zone, a fault that ends or dissipates without a clear connection.”
"We want to know how it formed, why it formed," says Dr. Kevin P. Furlong, professor of geosciences. "We know the San Andreas boundary is getting longer as the Mendocino Triple Junction point moves northward. Right now we believe that the Eastern California Shear Zone is growing along with the San Andreas."

“The Eastern California Shear Zone runs roughly parallel to the San Andreas Fault from the gulf of California and is a wide area in western Nevada. The problem is that so far, no one has identified the northern end of the zone.”

“Basic plate tectonics requires that the large plates that make up the Earth's crust move over or under each other, slide above or below each other, or meet end to end forming large mountainous plateaus. In the California-Nevada area, most of the plate boundaries behave nicely. The Pacific plate slides northward while the North American Plate slides southward. The Juan de Fuca plate in the north slides beneath the North American plate and all three of these plates meet at a point near Mendocino, California, called the Mendocino Triple Junction. For the most part, seismologists understand how these three plates move.”

“However, the Eastern California Shear Zone, sometimes called Walker Lane, does not act properly. No obvious connection of the northern end of the zone with another plate boundary exits.”

"This would not be a problem if the slip were not significant, but the slip is significant," Furlong told attendees at the 117th annual meeting of the Geological Society of America today (Oct. 17) in Salt Lake City. "The total displacement has been 50 kilometers and we know it has been going on for 5 to 6 million years."

http://www.eurekalert.org/pub_releases/2005-10/ps-ecs101405.php

• ECSZ