GPS Measurements at Vandenberg AFB
Abstract
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 strain/yr. 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 mm/yr oriented at N3E+ or - 13. This vector can be decomposed into 6 + or - 2 mm/yr of crustal shortening on the general structural trend of N30E and 3+ or -1 mm/yr of right-lateral shear across the axis.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 14, 1992
- Accession Number
- ADA254978
Entities
People
- Robert W. King
Organizations
- Massachusetts Institute of Technology