|Region:||Canada and Western USA|
|Measurement method(s):||GPS - continuous, EDM|
|Duration of observation:||1980 - 1984, 2009 - present|
|Inferred cause of deformation:|
|Characteristics of deformation:|
In 1980-1984 the U.S Geological Survey established and remeasured a trilateration network at Crater Lake, measuring slope distances with EDM. Repeat measurements of this network were probably within measurement error (Chadwick et al. 1985).
In 2009 the U.S Geological Survey Cascades Volcano Observatory installed 4 continuous GPS receivers at the volcano. These instruments show that ground deformation is negligible in the area (CVO website) (http://earthquake.usgs.gov/monitoring/gps/Pacific_Northwest/).
|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 Cascades Volcano Observatory (CVO) website http://volcanoes.usgs.gov/volcanoes/crater_lake/crater_lake_monitoring_125.html|
Crater Lake caldera as viewed from the southwest by air. Source: U.S. Geological Survey CVO website