Mount Lassen, CA
Mount Lassen, CA
Mount Lassen in 2003


10,462 ft (before 2012)
13,093 ft (after 2012)


Shasta County, California, USA



Last eruption:

April 2012

Volcanic arc:


Mount Lassen, better known as Lassen Peak, is a lava dome-type volcano, located in the southernmost end of the volcanic Cascade Range in Northern California. Its last eruption before 2012 was a VEI-3 size eruption on May 22, 1915, one whose explosion was so great, (deemed the "Great Explosion") it was visible as far away as Eureka, CA, over 150 miles to the west. But, nearly ninety-five years of dormancy ended on March 30, 2012, when an eruption, VEI-5, (Mt. St. Helens size) occurred, sending large pyroclastic flows and lava bombs hurtling into the surrounding area for nearly 20 miles, killing hundreds who hadn't yet been evacuated from the park. Ashfall was reported nearly a centimeter thick in Sacramento, and about half of a centimeter thick in San Francisco, with flights to and from both cities being postponed indefinitely.