U.S. Geological Survey Scientific Investigations Report 2012–5176–A
Eruption column of the May 22, 1915, eruption of Lassen Peak viewed from downtown Red Bluff, California.
The Lassen region of the southernmost Cascade Range is an active volcanic area. At least 70 eruptions have occurred in the past 100,000 years, including 3 in the past 1,000 years, most recently in 1915. The record of past eruptions and the present state of the underlying magmatic and hydrothermal systems make it clear that future eruptions within the Lassen Volcanic Center are very likely. Although the annual probability of an eruption is small, the consequences of some types of eruptions could be severe. Compared to those of a typical Cascade composite volcano, eruptive vents at Lassen Volcanic Center and the surrounding area are widely dispersed, extending in a zone about 50 km wide from the southern boundary of Lassen Volcanic National Park north to the Pit River. This report presents a discussion of volcanic and other geologic hazards in the Lassen area and delineates hazards zones for different types of volcanic activity.
Owing to its presence in a national park with significant visitorship, its explosive behavior, and its proximity to regional infrastructure, the Lassen Volcanic Center has been designated a “high threat volcano” in the U.S. Geological Survey National Volcano Early Warning System assessment. Volcanic eruptions are typically preceded by seismic activity and ground deformation, and the Lassen area has a network of seismometers and Global Positioning System stations in place to monitor for early warning of volcanic activity.
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Clynne, M.A., Robinson, J.E., Nathenson, M., and Muffler, L.J.P., 2012, Volcano hazards assessment for the Lassen region, northern California: U.S. Geological Survey Scientific Investigations Report 2012–5176–A, 47 p., 1 plate, Scale 1:200,000. (Available at http://pubs.usgs.gov/sir/2012/5176/a/.)
Types of Volcano Hazards and Effects of Volcanic Eruptions
Volcanism in the Lassen Region
Magma Beneath the Lassen Volcanic Center
Lassen Hydrothermal System
Seismicity and Ground Deformation
Volcano-Related Hazards in the Lassen Region
Volcanic Event Frequency, Probability and Magnitude