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Author Gordon, R. G.
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword GEOSCIENCES ♦ CALIFORNIA ♦ GEOLOGIC FORMATIONS ♦ GEODETIC SURVEYS ♦ CONTINENTAL CRUST ♦ DEFORMATION ♦ GEOLOGIC FAULTS ♦ INTERFEROMETRY ♦ OCEANIC CRUST ♦ PLATE TECTONICS ♦ ROTATION ♦ STRATA MOVEMENT ♦ DEVELOPED COUNTRIES ♦ EARTH CRUST ♦ GEOLOGIC FRACTURES ♦ GEOLOGIC STRUCTURES ♦ GEOPHYSICAL SURVEYS ♦ MOTION ♦ NORTH AMERICA ♦ SURVEYS ♦ TECTONICS ♦ USA ♦ Geosciences
Abstract The authors use geodetic measurements from very long baseline interferometry to estimate the motion of the Sierra Nevadan microplate. The motion of the Sierra Nevadan microplate relative to the North American plate is described by a right-handed rotation of 0.61{degree}/m.y. about lat 32{degree}N, long 128{degree}W. This Euler pole predicts a significant counterclockwise rotation about a local vertical axis. It further predicts a velocity of the eastern edge of the Sierra Nevada relative to stable North America of 11 {plus minus}1 mm/yr toward N36{degree} {plus minus}3{degree}W, which accounts for about one-fourth of the velocity between the Pacific and North American plates and is {approximately}25{degree} clockwise of many prior estimates. The velocity nearly parallels the boundary between the Sierra Nevada and the Great Basin, which implies that current motion within the Great Basin results in a rotational, noncoaxial deformation. The authors use this velocity to estimate how motion is distributed across the broad deforming zone taking up Pacific-North America plate motion. They find that the vector sum of strike slip along the San Andreas fault and motion of the Sierra Nevada relative to stable North America (taken up by deformation within the Great Basin) differs little from the Pacific-north America plate velocity. The difference can be described at 36{degree}N along the San Andreas fault by a vector of 6 mm/yr directed toward N20{degree}W. This vector resolves into components of 5 mm/yr parallel to the fault and 2 mm/yr perpendicular to the fault with 95% confidence intervals of 0 to 10 mm/yr and {minus}1 to +5 mm/yr, respectively. The authors conclude that motion previously inferred to be taken up by deformation other than strike slip along the San Andreas fault or deformation within the Great Basin is much smaller than previously thought.
ISSN 00917613
Educational Use Research
Learning Resource Type Article
Publisher Date 1991-11-01
Publisher Place United States
Journal Geology
Volume Number 19
Issue Number 11


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