Browsing by Author "Dixon, Timothy H."

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    Decelerating Nazca-South America and Nazca-Pacific plate motions
    (American Geophysical Union, 1999) Norabuena Ortiz, Edmundo; Dixon, Timothy H.; Stein, Seth; Harrison, Christopher G. A.
    Space geodetic estimates of the rate of Nazca-South America convergence and Nazca-Pacific spreading averaging over several years show that present day rates are significantly slower than the 3 million year average NUVEL-1A model. The implied rates of deceleration are consistent with longer term trends extending back to at least 20 Ma, about the time of initiation of Andes growth, and may reflect consequences of ongoing subduction and construction of the Andes, e.g., increased friction and viscous drag on the subducted slab as the leading edge of South America thickens.
    Palabras clave:Space geodesyTectonic plateSubduction
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    Paleoseismology and global positioning system: earthquake-cycle effects and geodetic versus geologic fault slip rates in the Eastern California shear zone
    (Geological Society of America, 2003) Norabuena Ortiz, Edmundo; Dixon, Timothy H.; Hotaling, L.
    Published slip rates for the Owens Valley fault zone in eastern California based on geodetic data and elastic half-space models (5–7 mm/yr) are faster than longer term geologic rates (2–3 mm/yr). We use Global Positioning System data spanning the central Owens Valley, a more realistic rheological model with an elastic upper crust over a viscoelastic lower crust and upper mantle, and paleoseismic data from adjacent faults, to show that this difference could reflect earthquake-cycle effects. We estimate a long-term rate (2.1 ± 0.7 mm/yr) and earthquake recurrence interval (2750 +350/−1000 yr) from the geodetic data, both in agreement with independent geologic estimates.
    Palabras clave:EarthquakesPaleoseismologyGeological faults