California, United States
(also known as Mount Lassen) is the southernmost active volcano in the Cascade Range. It is part of the Cascade Volcanic Arc which is an arc that stretches from northern California to southwestern British Columbia. Located in the Shasta Cascade region of Northern California, Lassen rises 2000 feet above the surrounding terrain and has a volume of half a cubic mile, making it one of the largest lava domes on Earth.
It was created on the destroyed northeastern flank of now gone Mount Tehama, a stratovolcano that was at least 1000 feet higher than Lassen.
Lassen Peak has the distinction of being the only volcano in the Cascades other than Mount St. Helens to erupt during the 20th century. On May 22, 1915, an explosive eruption at Lassen Peak devastated nearby areas and rained volcanic ash as far away as 200 miles to the east. This explosion was the most powerful in a 1914–17 series of eruptions that were the last to occur in the Cascades before the 1980 eruption of Mount St. Helens in Washington. Lassen Volcanic National Park was created in Shasta County, California to preserve the devastated area and nearby volcanic geothermal features.
Unlike most lava domes, Lassen is topped by craters. A series of these craters exist around Lassen's summit, although two are now covered by solidified lava and sulfur deposits. Lassen is the largest of a group of more than 30 volcanoes that have erupted over the past 300,000 years in the Lassen Volcanic Center.
Lassen has the highest known snowfall amounts for California with an average annual snowfall of 660 inches and some years receiving over 1000 inches of snow at its base of 8250 feet at Lake Helen. Mount Lassen gets more precipitation (rain, hail, melted snow) than anywhere in the Cascades south of the Three Sisters volcanoes.
This heavy snowfall allows Lassen to retain 14 permanent patches of snow despite Lassen's modest elevation.
Lightning has been known to frequently strike the summit of the volcano during summer thunderstorms.