Lassen Peak’s 1915 eruption created the largest volcanic blast in California’s recorded history.
On 30 May 1915, Lassen Peak produced a powerful explosive eruption that generated an ash cloud, hot gases, and a volcanic mudflow. The event devastated parts of the surrounding landscape and left an area now known as the Devastated Area.
Lassen Peak is the southernmost major volcano in the Cascade Range. It is a plug dome, a type of volcano formed when viscous lava rises and solidifies near a vent. The mountain is part of Lassen Volcanic National Park, where visitors can see evidence of geothermal activity.
The eruption is sometimes overshadowed by larger Cascade eruptions, especially Mount Saint Helens in 1980. However, Lassen’s 1915 event remains California’s best-documented major volcanic eruption in historic times.