• Lassen Peak from Hat Creek

    Lassen Volcanic

    National Park California

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  • Road through the park is closed

    Park highway (HWY 89) is currently being cleared of snow, debris, and rocks. Anticipated opening for Memorial Weekend. More »

  • Park highway under construction near Sulphur Works

    Road crews are working to repair the road near Sulphur Works hydrothermal area. Road will be closed at the Kohm Yah-mah-nee Visitor Center during the week, and open to Sulphur Works on the weekends.

Volcanoes / Lava Flows

Nature and Science

Lassen Peak in mild eruption, 1915

(B. F. Loomis)

Every rock at Lassen originates from volcanoes. Lassen's volcanic domes are part of the most recently active Lassen Volcanic Center, which began to erupt about 825,000 years ago. Represented in the park are all four types of volcanoes found in the world--shield, composite, cinder cone, and plug dome. Unlike other Cascade volcanoes, Lassen's large plug dome and composite volcanoes are in close proximity to the smaller cinder cone volcanoes that surround the volcanic center.

The greater Lassen area has been volcanically active for about three millions years. Recently the region has seen eruptions from Cinder Cone (~350 years ago) and Lassen Peak (~100 years ago). While the area sleeps now, steam vents, boiling springs, and bubbling mudpots remain active--direct evidence that the volcanic center still smolders. No one can say when or where the next eruption will occur. We can only say that it will.

Studying and Monitoring Volcanic Activity
Scientists from United States Geological Survey (USGS) study volcanic activity at Lassen Volcanic National Park as a part of the USGS Volcano Hazards Program, California Volcano Observatory (CalVO). CalVO aims to advance scientific understanding of volcanic processes and lessen the harmful impacts of volcanic activity in the volcanically active areas of California and Nevada. Select a link below to learn more.

Lassen Volcanic Interactive Monitoring Map
View real-time data on seismic stations and park earthquakes

"Hot Water" in Lassen Volcanic National Park
Fumaroles, Steaming Ground, and Boiling Mudpots (pdf, 2.4 MB)

Eruptions of Lassen Peak
California, 1914-1917 (pdf, 588 KB)

How Old is "Cinder Cone"?
Solving a Mystery in Lassen Volcanic Park, California (pdf, 3.2 MB)

Lahar Hazard Zones for Eruption-Generated Lahars
in the Lassen Volcanic Center, California (pdf, 5.8 MB)

Volcano Hazards Assessment for the Lassen Region
Northern California (pdf, 27.7 MB)

Eruption Probabilities for the Lassen Volcanic Center
and Regional Volcanism Northern California, and Probabilities for Large Explosive Eruptions in the Cascade Range web (pdf, 1.1 MB)

Did You Know?

picture of caldera inside cinder cone

All four types of volcanoes found in the entire world are represented in Lassen Volcanic National Park.  Volcanoes found in the park include shield (Prospect Peak), plug dome (Lassen Peak), Cinder Cone (Cinder Cone), and Composite (Brokeoff Volcano) volcanoes. More...