CALREF, a stable reference frame for northern California

The BARD dataset has been processed in the ITRF2000 (Altamimi et al., 2002). The solutions (Houlié and Romanowicz, in prep) are in good agreement with campaign solutions (BAVU and USGS) previously released (d'Alessio et al., 2005). The new coordinates release of the BARD network includes the presently operating sites and the velocity of the sites already transferred from BSL to PBO during the last two years.

Figure 3.17: Comparison of the BARD solutions (white arrows) with the Bay Area Velocity Unification (BAVU) solutions (black arrows). All the data available at the BSL between 1994 and 2006 have been reprocessed (From Houlié and Romanowicz, in prep). BAVU website: http://seismo.berkeley.edu/ burgmann/RESEARCH/BAVU/
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Table 3.12: Comparison between previous published values and recomputed values. The adjustment with the ITRF2000 is good. The errors provided here are formal and cannot be qualified as realistic (From Houlié and Romanowicz, in prep).
Sites Lon. Lat. $dV_e$ $dV_n$
  (deg.) (deg.) (mm/y) (mm/y)
BAY1 197 .293 55 .19 -0 .03 0 .01
GOLD 243 .111 35 .425 1 .20 -0 .11
JPLM 241 .827 34 .205 0 .50 0 .59
PPT1 237 .61 37 .187 0 .82 0.27
VNDP 239 .384 34 .556 -0 .05 -0 .81


All the BARD sites have been processed jointly with IGS sites in California. No a priori constraints have been assumed during the processing. All the velocities included in the first release of California Reference Frame (CALREF) are given in Table 3.13. The CALREF will provide velocities and coordinates of sites located in the bay area at specific epochs. Each solution will be associated with error estimations (formal and real). Every surveyor will be able to control the reference site coordinates for a given survey.

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