15_Selected_Eruptions_in_History 2

The May 22, 1915 eruption of Lassen Peak as seen from Red Bluff, California.

Xjavier Murray
12-03-2015

On May 22, 1915, an explosive eruption at
Lassen Peak

This is the southernmost active volcano in the
Cascade Range, 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 Mt. St. Helens.

Lassen Peak is the largest of a group of more
than 30 volcanic domes erupted over the past
300,000 years in Lassen Volcanic National
Park.

Type Lava dome , Composite

Age of rock Less than 27,000 years

Volcanic arc Cascade Volcanic Arc

Last eruption 1914 to 1917

Magma Content- High Silica , Low Water

Easiest route Hike

Location Shasta County, California, U.S.

Range Cascade Range

Coordinates 40°29′17″N 121°30′18″WCoordinates: 40°29′17″N 121°30′18″W



Because of the eruptive activity, which
continued through 1917, and the area's stark
volcanic beauty, Lassen Peak, Cinder Cone
and the area surrounding were declared a
National Park on August 9, 1916.

On May 19, 1915, the mountaintop
exploded Lava crashed through the 1914
crater. A 20-foot-high wall of mud, ash, and
melted snow roared down the mountain,
snapping tree trunks. Three days later, a huge
mass of ashes and gases shot out of the
volcano, devastating a swath a mile wide and
three miles long. Above the havoc a cloud of
volcanic steam and ash rose 30,000 feet.