Hi All. “Between 1980 and 1984, the U. S. Geological Survey's David A. Johnston Cascades Volcano Observatory (CVO) established baseline geodetic networks at Mount Baker, Mount Rainer, and Mount St. Helens in Washington, Mount Hood and Crater Lake in Oregon, and Mount Shasta and Lassen Peak in California. To this list of potentially active volcanoes, CVO extended its monitoring program in 1985 to include Newberry and South Sister volcanoes in central Oregon. The Newberry and South Sister networks were re-measured in 1986 and will be measured periodically in future years. Improvements since 1984 in the recording of endpoint and flightline temperatures resulted in better overall data than obtained previously. The improvements included: calibration of all the sensors and precision thermistors, installation of a new recording system for flightline data, and recording of endpoint temperatures 6 meters above ground level. The data collected in 1985 and 1986 indicate little or no apparent deformation at either volcano between surveys.”

The newest data collected for the area show the uplifting is centered 5 km (3 mi) west of the South Sister volcano in the Three Sisters region of the Oregon Cascade Range.

It appears that South Sister is the youngest volcano in the area. The latest eruptions on South Sister occurred about 2,000 years ago. Initial explosive eruptions produced small pyroclastic flows and tephra fallout from several aligned vents low on the south flank.

When viewing the Three Sisters volcanos from above it can be seen that they are very close together. It would appear that they were formed by a hot spot, but everything I have found so far indicates they are subduction type volcanos. This recent uplifting may be the beginnings of the birth of a forth Sister. Take Care…Don in creepy town.

• Three Sisters