Engineering topics
Publications and source records attributed to Webb, F..
Data from SIR-C and ERS-1 were used in an attempt to measure uplift in the Long Valley area of northern California using differential inteferometric techniques.
The results using interferometric synthetic aperture radar(SAR) to measure the co-seismic displacement from the June 28, 1992 Landers earthquake suggest that this technique may be applicable to other problems in crustal deformation.
The Southern California Earthquake Center is coordinating a effort by scientists at the Jet Propulsion Laboratory, the U.S. Geological Survey, and various academic institutions to establish a dense 250 station, continuously recording GPS geodetic array in southern California for measuring crustal deformation associated with slip on the numerous faults that underlie the major metropolitan areas of southern california.
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Velocities and positions for 41 globally distributed sites have been determined from GPS data spanning three years.
Beginning June 1992 and continuing indefinitely as part of our contribution to FLINN (Fiducial Laboratories for an International Natural Science Network), DOSE (NASA's Dynamics of the Solid Earth Program), and the IGS (International GPS Geodynamics Service), analysts at the Jet Propulsion Laboratory (JPL) have routinely been reducing data from a globally-distributed network of Rogue Global Positioning System (GPS) receivers.
A permanent Global Positioning System receiver at Casa Diablo Hot Springs, Long Valley Caldera, California was installed in January, 1993, and has operated almost continuously since then.
A generalized no-fiducial approach has been developed to obtain global positions and velocities without fixing any individual position or velocity components. The method used can be applied to any global geodetic technique and proceeds in three general steps. First, daily solutions derived with weak constraints are combined to yield one global set of positions and velocities. Second, 14 minimal constraints are applied to remove uncertainties due to the loosely defined reference frame. Third, transformation from one reference frame to another is accomplished with a 14 parameter transformation. One year of daily FLINN solutions, each made with data from about 40 sites, have been combined to yield our best fit global model...
This paper describes the constraints on long-term, post-seismic deformation within the Mojave Desert and on cumulative slip across the northern part of the Eastern California shear zone from May 1991 to August 1993.
This paper describes the GPS-determined, far-field coseismic displacements that differ significantly from elastic half-space models, offering new insight on the role of regional scale heterogeneity in crustal structure.
Aeolian control of large scale surface texture is apparent in orbiter images from selected regions of Mars -- the polar areas, equatorial canyons, and some craters. At other locations on Mars there is evidence suggesting aeolian control on meter scales within a context provided by larger landforms.