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FOR RELEASE DECEMBER 7 OR THEREAFTER

       New information on the rate of crustal deformation along earthquake faults in central and southern California was presented Thursday by Jet Propulsion Laboratory scientist before science conference in San Francisco.

       Kristine M. Larson based her estimates on Global Positioning System (GPS) data collected between June 1986 and March 1989. Her paper was presented before the 1989 Fall Meeting of the American Geophysical Union.

       The data sets spanned both large and small tectonic features which make up the North American-Pacific plate boundary.

       Her paper covers three networks: one spanning the San Andreas fault and California coastal range, another crossing the Santa Barbara Channel and the third designed to measure deformation, if any, between the southern California coast and the offshore islands of San Clemente, Santa Catalina and San Nicolas.

       GPS measurements of relative motion across the San Andreas of 33 plus or minus 5) millimeters per year are consistent in magnitude and orientation with previous geologic and geodesic estimates, she said. The offshore regions are deforming at rates on the order of 10 mm per year, again with an uncertainty of 5 mm per year.

       Larson was scheduled to present her paper at an afternoon meeting Thursday, Dec. 7.

       The study was performed at JPL under contract with NASA. The data was collected by the United States Geological Survey, National Geodetic Survey, UCLA, UCSD, Massachusetts Institute of Technology, Caltech and JPL.

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