Mount Baker viewed to the west. Increased fumarolic activity occurred in Sherman Crater (left of summit) during the mid-1970's.

Mount Baker, Washington. Eyewitness reports of small ashy plumes and active steam vents on Mount Baker dating as far back as the mid-1800's were clear evidence that the ice-covered volcano had one of the most active geothermal systems among Cascade volcanoes. When new fumaroles and unusually dark vapor plumes appeared abruptly in March 1975, however, people in the Northwest became concerned about an impending eruption and possible avalanches and lahars from Sherman Crater, a vent just south of Mount Baker's summit. Despite a tenfold increase in the release of heat by the volcano during the next 12 months, which resulted in extensive changes to the ice cover in Sherman Crater and produced minor releases of ash, no eruption occurred. The thermal activity was not accompanied by earthquakes, which generally precede most eruptions, and since 1976, the volcano has not showed additional signs of activity.

The increased thermal activity between 1975 and 1976 prompted public officials and Puget Power* to temporarily close public access to the popular Baker Lake recreation area and to lower the reservoir's water level by 10 meters. Significant avalanches of debris from the Sherman Crater area could have swept directly into the reservoir, triggering a disastrous wave that would have caused loss of life and damage to the reservoir.
*Now Puget Sound Energy.

<https://pubs.usgs.gov/gip/volcus/page18.html>
Maintained by John Watson
Updated 04.28.99