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Quantifying Seismic Hazard in the Southern Rocky Mountains through GPS Measurements of Crustal Deformation |
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Established baseline geodetic measurements to determine tectonic activity in the Rocky Mountains. Repeating these measurements in several years will quantify deformation for the first time. One way of obtaining crustal deformation rates is by comparing two sets of high-precision GPS measurements taken at the same network of points at two different times. The total errors in the two sets of measurements must be small enough so that the accumulated movement within the network during the intervening time period can overcome the noise. Our aims were two-fold: to acquire a new set of measurements statewide in 2001 that are of the highest possible precision using state of the art acquisition and processing techniques using a previously established set of control points: and to reprocess data measured on these points 10 years earlier to high enough precision to obtain an estimate of crustal strain without requiring a future remeasurement. The level of precision necessary to use GPS for tectonic studies can only be obtained by extensive postprocessing of data that were obtained using proper field procedures, and if the GPS satellite orbits can be post-processed to a high level of precision using a global tracking network. This tracking network has been in place and orbits calculated by the International GPS Service since 1992, but as the original measurements were done in 1991, we are trying to devise our own strategy to improve the accuracy of the satellite orbits. Furthermore, the 1991 data were acquired by the National Geodetic Survey for geodetic data definition and not tectonic studies, so the potential accuracy of the reprocessed results is reduced even further, adding to the challenge of obtaining an immediate result. Given the anticipated low rates of strain in the region, we must reduce the present errors in the reprocessed data by two orders of magnitude from its current levels if a meaningful result is to be calculated. |
CIRES Research Theme Project Personnel Funding Source(s) Publications |
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216 UCB