GPS Measurements at Vandenberg AFB
Annual rept. 15 Jan 1991-14 Jan 1992
MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF EARTH ATMOSPHERIC AND PLANETARY SCIENCES
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The objective was to measure directly the tectonic deformation in the Santa Maria Fold and Thrust Belt SMFTB, northwest of Santa Barbara California. The principal measurement technique was space geodesy using microwave signals transmitted by Block II satellites of the Global Positioning System GPS, from March to August 1990. Geodetic observations were analyzed to resolve tectonic deformation across the SMFTB. The geodetic network forms a braced quadrilateral with 40 km sides whose southwest corner is the Vandenberg very long baseline interferometry VLBI station. Three different types of data were combined to estimate two-dimensional station position and strain rate parameters simultaneously. Significant strain rates were discovered using a model which constrains the relative velocity field to be linear in space and constant in time. The maximum compressive strain is oriented N17e-5E, and the compressive strain rate in that direction is 0.13 or - 0.03 strainyr. Under the assumption that the unresolved rotational component of the velocity field is zero, the integrated rate of deformation across the basin was estimated at 7 or - 1 mmyr oriented at N3E or - 13. This vector can be decomposed into 6 or - 2 mmyr of crustal shortening on the general structural trend of N30E and 3 or -1 mmyr of right-lateral shear across the axis.
- Geology, Geochemistry and Mineralogy
- Navigation and Guidance