North American—Pacific Relative Plate Motion in Southern California from Interferometry

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Science  12 Sep 1986:
Vol. 233, Issue 4769, pp. 1181-1183
DOI: 10.1126/science.233.4769.1181


Very long baseline interferometry measurements of baselines crossing the San Andreas fault zone in southern California have provided observational constraints on rates of elastic tectonic strain accumulation. The single site located near this fault (the Jet Propulsion Laboratory site) moves in a direction concordant with the Pacific plate motion vector but at approximately half the net rate relative to North America. This motion agrees approximately in amount with geologically determined displacement rates on the San Andreas fault alone but not with the local strike of the fault. When considered together with complementary geodetic data, these results suggest a complex relation between the short-term accumulation of elastic strain and its permanent accommodation on existing faults.