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Tectonic Geodesy
Group 2 – Tectonic Geodesy | Poster Abstracts
2-014
GEOEARTHSCOPE: NEWLY ACQUIRED AERIAL AND SATELLITE IMAGERY AND
GEOCHRONOLOGY Phillips DA, Jackson ME, and Meertens CM
UNAVCO has acquired aerial and satellite imagery and geochronology as part of GeoEarthScope, a
component of the EarthScope Facility project funded by the National Science Foundation. All
GeoEarthScope airborne LiDAR data acquisitions are now complete and cover a total area of more
than 5000 square kilometers. Of particular interest to the SCEC community, we have collected high
resolution airborne LiDAR imagery of major fault systems in southern and eastern California
including the Garlock fault, the Elsinore fault, and numerous other active faults and structures in
the Mojave, Panamint valley, Owens valley and elsewhere. These LiDAR data were collected in
Spring 2008 and preliminary processed imagery will be shown. These new LiDAR data
complement the previously acquired B4 and GeoEarthScope NoCal LiDAR datasets. In addition to
airborne LiDAR imagery, we have acquired a significant volume of InSAR imagery covering
southern California and other targets within the EarthScope footprint from several satellites,
including ERS-1/2, ENVISAT and RADARSAT. ENVISAT satellite tasking for GeoEarthScope will
continue through and conclude on September 30, 2008. Besides imagery data, twelve
geochronology labs have been funded to provide analysis services including 14C, OSL,
Cosmogenic, (U-TH)/He, Fission Track, 40Ar/39Ar and U-Pb dating techniques.
2-019
IMPROVING PRESENT-DAY LOADING RATE ESTIMATES FOR THE
SOUTHERNMOST SAN ANDREAS FAULT USING THE JOSHUA TREE AND SAN
BERNARDINO GPS NETWORKS Spinler JC, Bennett RA, Anderson ML, Hreinsdottir S, and
McGill SF
We present the first results from a new dense network of Global Positioning System (GPS) stations
located in the eastern Transverse Ranges Province (ETR), a transition zone between the southern
San Andreas fault (SSAF) and eastern California shear zone (ECSZ). The Joshua Tree Integrative
Geodetic Network (JOIGN) is composed of 23 campaign stations, which have been observed each
May, September, and February from September 2005 to September 2007. We also analyzed data
from 37 nearby continuous stations from the PBO NUCLEUS-SCIGN and PBO GPS networks
(1994-2007), and an additional 7 campaign sites located in the San Bernardino Mountains. We used
the GPS-determined site velocity estimates and elastic block models to constrain loading rates for
model faults for four fault-block scenarios. For each model, we estimated relative block motions
accounting for elastic strain on locked faults using a weighted least squares algorithm that
annihilates common mode rotation and translation attributable to reference frame errors. We tested
models variously representing the Pinto Mountain and Blue Cut faults of the ETR, a hypothetical
new NNW striking fault (the "Landers-Mojave earthquake line") that cuts obliquely across the ETR
and Mojave Desert faults, and models including various combinations of these end-member faultblock
models. All models produce fault loading rate estimates for the SSAF that reduce the
discrepancy between previous geodetic loading rate models and the majority of estimates for
intermediate- and short-term fault slip rates based on tectonic geomorphology and
paleoseismology. We attribute the improved match between long- and short-term loading/slip-rate
estimates to a more realistic parameterization of the fault system in the ETR, which allows geodetic
estimates for SSAF slip to vary along strike from 21.0-21.5 ± 0.1 mm/yr in the Coachella Valley to
3.2-5.6 ± 0.1 mm/yr near San Bernardino, depending on the model. However, our slip rate
estimates are markedly different from the overall temporal-average slip rate of 30 mm/yr based on
2008 SCEC Annual Meeting | 147