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New data resolve stressful problem.

Five years ago, when Mary Lou Zoback of the U.S. Geological Survey in Menlo Park, Calif., and Mark D. Zoback of Stanford University compiled stress measurements of the North American continental crust, they were left with a perlexing problem: Compressive stresses along the Eastern Seaboard ran in a northwest direction, while stresses in hte rest of the continent, out to the Rocky Mountains, were oriented toward the northeast (SN: 6/14/80, p. 372). Moreover, both of the two main theories explaining why the continent is stressed predicted northeast stress from the Atlantic to the midcontinent.

"When we did the original compilation we included everything we could get our hands on because there wasn't much data," says Mary Lou Zoback. Now, with many more and better stress measurements, the Zobacks report that stresses along the East Coast range between north-45 [deg.] east to north-70 [deg.] east. The revised North American stress data still do not reveal which of the stress theories is correct, but at least the stress pattern puzzle has been resolved.
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Title Annotation:stress measurements of North American continental crust
Publication:Science News
Date:Dec 21, 1985
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