Which volcanoes in the conterminous United States have erupted since the Nation was founded?
Excluding steam eruptions, these volcanoes have shown activity:
- Mount St. Helens, Washington - Eruptions and/or lava dome growth occurred in the late 1700s, 1800-1857, 1980-1986, and 2004-2007.
- Lassen Peak, California - A series of steam blasts began on May 30, 1914. An eruption occurred 12 months later on May 21, 1915. Minor activity continued through the middle of 1917.
- Mount Shasta, California - The last known eruption occurred about 200 radiocarbon years ago, possibly in 1786. Evidence for this eruption, recorded from sea by the explorer La Perouse, is somewhat ambiguous, but his description could only have referred to Mount Shasta.
- Mount Hood, Oregon - After being dormant for over 1,000 years, Mount Hood had an eruptive period beginning in 1781 that lasted for about a decade. In the mid-1800s, local residents reported minor explosive activity.
Ever Vigilant: USGS Marks the 37th Anniversary of Mount St. Helen's Eruption and the 35th Anniversary of the Cascades Volcano Observatory
Today, in 1980, Mount St. Helens unleashed the most devastating eruption in U.S. history. Two years later, USGS founded the Cascades Volcano Observatory to monitor Mount St. Helens and all the Cascades Volcanoes.
May is Volcano Preparedness Month in Washington, providing residents an opportunity to become more familiar with volcano hazards in their communities and learn about steps they can take to reduce potential impacts.
2015 marks the 100th anniversary of the May 22, 1915 explosive volcanic eruption of Lassen Peak in northern California.
Left: Before the eruption of May 18, 1980, Mount St. Helens' elevation was 2,950 m (9,677 ft). View from the west, Mount Adams in distance. S. Fork Toutle River is valley in center of photo.
Right: Mount St. Helens soon after the May 18, 1980 eruption, as viewed from Johnston's Ridge.
Title: A Sight "Fearfully Grand" Eruptions of Lassen Peak, California, 1914 to1917
- A summary of the eruptions and their effects
- Illustrated with historical photographs
--a wonderland of volcanoes and thermal features
By Patrick Muffler, Geologist Emeritus
- Lassen Peak, the southernmost active volcano in the Cascade Range,explosively erupted in 1915, devastating nearby areas and raining volcanic ash as far away as 200 miles to the east
- Lassen National Park, in addition to
The May 18, 1980 eruption of Mount St. Helens triggered a growth in volcano science and volcano monitoring. Five USGS volcano observatories have been established since the eruption. With new technologies and improved awareness of volcanic hazards USGS scientists are helping save lives and property across the planet.