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Crater Lake

Find U.S. Volcano

Crater Lake partly fills one of the most visually spectacular calderas of the world, an 8-by-10-km (5-by-6-mi) basin more than 1 km (0.6 mi) deep formed by collapse of the volcano known as Mount Mazama during a series of explosive eruptions about 7,700 years ago.

Quick Facts

Location: Oregon, Klamath County

Latitude: 42.93° N

Longitude: 122.12° W

Elevation: 2,487 (m) 8,159 (f)

Volcano type: Caldera

Composition: Basalt to Rhyolite

Most recent eruption: 6,600 years ago

Threat Potential: Very High*

*based on the National Volcano Early Warning System

Summary

Crater Lake at sunrise. Shadows coat the blue waters. Red orange light hits the east side of the rocky caldera.
Crater Lake.

Having a maximum depth of 594 m (1,949 ft), Crater Lake is the deepest lake in the United States. Mount Mazama straddles the Cascade volcanic axis and is a cluster of overlapping stratovolcanoes that is the most voluminous Quaternary volcanic system in the Oregon Cascades. The volcano's compound edifice has been active relatively continuously since 420,000 years ago, and it is built mostly of andesite to dacite until it began erupting rhyodacite about 30,000 years ago, ramping up to the caldera-forming eruption. Excellent preservation and easy access make Mount Mazama, Crater Lake caldera, and the deposits formed by the climactic eruption constitute a natural laboratory for study of volcanic and magmatic processes. Research relating to the caldera-forming eruption has been of fundamental importance to volcanologists, helping them to understand large explosive eruptions, compositional zonation in magma chambers, and collapse caldera mechanisms. The climactic eruption is also the source of the widespread Mazama ash, a useful Holocene stratigraphic marker throughout the Pacific Northwest, adjacent Canada, and offshore.

News

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Which U.S. volcanoes pose a threat?

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Geologic maps lay the foundation for this virtual tour of western states volcanoes.

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First earthquakes recorded at Crater Lake by new monitoring network.

Publications

Postglacial faulting near Crater Lake, Oregon, and its possible association with the Mazama caldera-forming eruption

Volcanoes of subduction-related magmatic arcs occur in a variety of crustal tectonic regimes, including where active faults indicate arc-normal extension. The Cascades arc volcano Mount Mazama overlaps on its west an ∼10-km-wide zone of ∼north-south–trending normal faults. A lidar (light detection and ranging) survey of Crater Lake National Park, reveals several previously unrecognized faults west
Authors
Charles R. Bacon, Joel E. Robinson

2018 update to the U.S. Geological Survey national volcanic threat assessment

When erupting, all volcanoes pose a degree of risk to people and infrastructure, however, the risks are not equivalent from one volcano to another because of differences in eruptive style and geographic location. Assessing the relative threats posed by U.S. volcanoes identifies which volcanoes warrant the greatest risk-mitigation efforts by the U.S. Geological Survey and its partners. This update

Authors
John W. Ewert, Angela K. Diefenbach, David W. Ramsey

Overview for geologic field-trip guides to Mount Mazama, Crater Lake Caldera, and Newberry Volcano, Oregon

These field-trip guides were written for the occasion of the International Association of Volcanology and Chemistry of the Earth’s Interior (IAVCEI) quadrennial scientific assembly in Portland, Oregon, in August 2017. The guide to Mount Mazama and Crater Lake caldera is an updated and expanded version of the guide (Bacon, 1989) for part of an earlier IAVCEI trip to the southern Cascade Range. The
Authors
Charles R. Bacon, Julie M. Donnelly-Nolan, Robert A. Jensen, Heather M. Wright

Science

Volcanic Hazards for the Crater Lake Region

Summary of volcanic hazards for the Crater Lake region.
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Volcanic Hazards for the Crater Lake Region

Summary of volcanic hazards for the Crater Lake region.
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Eruption History for Mount Mazama and Crater Lake Caldera

Eruption History for Mount Mazama and Crater Lake Caldera
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Eruption History for Mount Mazama and Crater Lake Caldera

Eruption History for Mount Mazama and Crater Lake Caldera
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Climactic Eruption of Mount Mazama formed Crater Lake

The climactic eruption of Mount Mazama devastated the terrain for tens of kilometers from the volcano, sent pyroclastic flows as far as 70 km (43 mi) down every valley heading on the volcano, and produced ash fall throughout much of the Pacific Northwest and parts of southern Canada.
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Climactic Eruption of Mount Mazama formed Crater Lake

The climactic eruption of Mount Mazama devastated the terrain for tens of kilometers from the volcano, sent pyroclastic flows as far as 70 km (43 mi) down every valley heading on the volcano, and produced ash fall throughout much of the Pacific Northwest and parts of southern Canada.
Learn More