|Region:||Canada and Western USA|
|Measurement method(s):||GPS - continuous, EDM|
|Duration of observation:||1980 - 1984, 2005 - present|
|Inferred cause of deformation:|
|Characteristics of deformation:|
In 1980-1984 the U.S Geological Survey established and remeasured a trilateration network at Shasta, measuring slope distances with EDM. Repeat measurements of this network were probably within measurement error (Chadwick et al. 1985).
Between 2005 – 2007 9 continuous GPS receivers were installed by UNAVCO and the USGS to make up the continuous monitoring network at Shasta. These instruments show that ground deformation is negligible in the area (CalVO website) (http://earthquake.usgs.gov/monitoring/gps/NCalifornia/).
|Reference:||Chadwick, W. W., Iwatsubo, E. Y., Swanson, D. A., and Ewert, J. W. (1985) Measurements of Slope Distances and Vertical Angles at Mount Baker and Mount Rainier, Washington, Mount Hood and Crater Lake, Oregon, and Mount Shasta and Lassen Peak, California, 1980-1984, US Department of the Interior, Geological Survey, Open File Report 85-205.|
|Reference:||USGS California Volcano Observatory (CalVO) website http://volcanoes.usgs.gov/volcanoes/mount_shasta/mount_shasta_monitoring_65.html|
View of Shasta from the west with the town of Weed visible in the foreground. Source: U.S. Geological Survey CalVO website