Crater Lake

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  • Country
  • Volcanic Region
  • Primary Volcano Type
  • Last Known Eruption
  • 42.93°N
  • 122.12°W

  • 2487 m
    8157 ft

  • 322160
  • Latitude
  • Longitude

  • Summit
    Elevation

  • Volcano
    Number

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The spectacular 8 x 10 km Crater Lake caldera in the southern Cascades of Oregon formed about 6850 years ago as a result of the collapse of a complex of overlapping shield and stratovolcanoes known as Mount Mazama. The cone-building stage, during which at least five andesitic and dacitic shields and stratovolcanoes were constructed, took place between about 420 and 40 thousand years ago (ka). A series of rhyodacitic lava domes and flows and associated pyroclastic rocks were erupted between about 30 ka and the climactic eruption. The explosive eruptions triggering collapse of the 8-10 km wide caldera about 7500 years ago were among Earth's largest known Holocene eruptions, distributing tephra as far away as Canada and producing pyroclastic flows that traveled 40 km from the volcano. A 5-km-wide ring fracture zone is thought to mark the original collapse diameter. The deep blue waters of North America's second deepest lake, at 600 m, fill the caldera to within 150-600 m of its rim. Post-caldera eruptions within a few hundred years of caldera formation constructed a series of small lava domes on the caldera floor, including the partially subaerial Wizard Island cinder cone, and the completely submerged Merriam Cone. The latest eruptions produced a small rhyodacitic lava dome beneath the lake surface east of Wizard Island about 4200 years ago.

Summary of Holocene eruption dates and Volcanic Explosivity Indices (VEI).

Start Date Stop Date Eruption Certainty VEI Evidence Activity Area or Unit
2850 BCE (?) Unknown Confirmed   Radiocarbon (corrected) Lava dome ENE of Wizard Island
5250 BCE (?) Unknown Confirmed   Tephrochronology Wizard Island and Merriam Cone
5550 BCE (?) Unknown Confirmed 0 Tephrochronology Central Platform
5680 BCE ± 150 years Unknown Confirmed 7 Ice Core Mt. Mazama summit and flank vents
5900 BCE ± 50 years Unknown Confirmed 6 Radiocarbon (corrected) North flank (Llao Rock)

This compilation of synonyms and subsidiary features may not be comprehensive. Features are organized into four major categories: Cones, Craters, Domes, and Thermal Features. Synonyms of features appear indented below the primary name. In some cases additional feature type, elevation, or location details are provided.


Synonyms

Mazama, Mount

Cones

Feature Name Feature Type Elevation Latitude Longitude
Bald Crater Pyroclastic cone 1974 m 43° 3' 0" N 122° 13' 0" W
Bear Butte Cone 1932 m 42° 59' 0" N 122° 0' 0" W
Cleetwood Vent 2135 m 42° 58' 59" N 122° 4' 0" W
Crater Peak Cone 2214 m 42° 51' 0" N 122° 5' 49" W
Danger Bay Stratovolcano 2050 m 42° 55' 0" N 122° 4' 0" W
Desert Cone Cone 2027 m 43° 12' 7" N 122° 9' 29" W
Dutton Cliff Stratovolcano 2484 m 42° 54' 0" N 122° 5' 0" W
Forgotten Cone Pyroclastic cone 2330 m 42° 57' 0" N 122° 10' 0" W
Hillman Peak Stratovolcano 2486 m 42° 57' 11" N 122° 10' 1" W
Llao Bay Shield volcano 2100 m 42° 58' 0" N 122° 8' 0" W
Llao Rock Vent 2452 m 42° 58' 23" N 122° 7' 59" W
Lookout Butte Cone 1865 m 42° 59' 0" N 121° 56' 0" W
Maklaks Crater
    Diller Cone
Pyroclastic cone 1945 m 42° 49' 59" N 122° 1' 1" W
Merriam Cone Pyroclastic cone 1734 m 42° 57' 43" N 122° 5' 42" W
Phantom Cone Stratovolcano 2300 m 42° 54' 0" N 122° 5' 0" W
Pothole Butte Cone 1877 m 42° 57' 0" N 121° 56' 0" W
Red Cone Cone 2247 m 43° 0' 0" N 122° 10' 1" W
Redcloud Vent 2423 m 42° 56' 0" N 122° 3' 0" W
Scott, Mount Stratovolcano 2721 m 42° 55' 30" N 122° 1' 1" W
Scout Hill Cone 1948 m 42° 58' 0" N 121° 58' 0" W
Sentinel Rock Stratovolcano 2141 m 42° 55' 0" N 122° 4' 0" W
Timber Crater Shield volcano 2256 m 43° 3' 0" N 122° 4' 0" W
Union Peak Cone 2346 m 42° 49' 59" N 122° 13' 30" W
Wizard Island Pyroclastic cone 2115 m 42° 56' 31" N 122° 8' 42" W

Craters

Feature Name Feature Type Elevation Latitude Longitude
Williams Crater
    Forgotten Crater
Crater - Cone 2330 m 42° 57' 18" N 122° 10' 37" W

Domes

Feature Name Feature Type Elevation Latitude Longitude
Grouse Hill Dome 2256 m 42° 59' 35" N 122° 7' 19" W
Merriam Point Dome 2200 m 42° 58' 0" N 122° 8' 0" W
Sharp Peak Dome 1818 m 43° 0' 0" N 122° 0' 29" W
This inconspicuous ridge rising above pastures of the Klamath River valley is actually the rim of Crater Lake caldera, one of the most dramatic features of the Cascade Range. Formation of the caldera about 6850 years ago truncated Mount Mazama, a complex of overlapping stratovolcanoes and shield volcanoes. The southern caldera rim is located above a point between the two larger trees at the left side of the photo. Mount Scott, a pre-caldera stratovolcano located east of the caldera rim, forms the small distant peak at the far right.

Photo by Lee Siebert, 1982 (Smithsonian Institution).
The lower, smooth north rim and jagged south rim of Crater Lake caldera are seen in the distance from the summit of Mt. Thielson to the north. The caldera was formed about 6850 years ago following one of the world's largest explosive eruptions. The eruption resulted in the collapse of ancestral Mount Mazama, a complex of overlapping shield and stratovolcanoes. Mount Scott, a pre-caldera stratovolcano, forms the high point on the left skyline, Timber Crater is the symmetrical cone below and left of the north caldera rim.

Photo by Lee Siebert, 1982 (Smithsonian Institution).
The massive Llao Rock lava flow, truncated in the NW wall of Crater Lake caldera, was emplaced at the end of a major eruption about 150 years prior to the formation of the caldera. The thin, light-colored unit in the caldera wall at the base of the lava flow, seen prominently on the right, is a plinian pumice deposit from that major explosive eruption, one of the largest in the Cascades during the Holocene. The lava flow, more than 350 m thick, is capped by tephra from the caldera-forming eruption of Crater Lake.

Photo by Lee Siebert, 1981 (Smithsonian Institution).
Wizard Island cinder cone, with a symmetrical 90-m-wide crater at its summit, formed above the west floor of Oregon's Crater Lake caldera within a few hundred years of caldera formation. A lava flow created the peninsula in the foreground on the NW side of the cone, which forms a small island on the west side of Crater Lake. A submerged dome, 30 m beneath the surface 1 km east of Wizard Island, is the youngest feature of Crater Lake caldera.

Photo by Lee Siebert, 1981 (Smithsonian Institution).
Devil's Backbone is a spectacular segmented dike that rises nearly 400 m from the shore of Crater Lake to the western rim of the caldera. The andesitic dike was a channel for a vent, now removed by glacial erosion, near Mount Hillman, the westernmost of the complex of overlapping stratovolcanoes forming ancestral Mount Mazama.

Photo by Lee Siebert, 1981 (Smithsonian Institution)
Pinnacles eroded from a pyroclastic-flow deposit from the caldera-forming eruption of Crater Lake mark former fumarole vents created by degassing of the pyroclastic flow. The rising gases hardened the loose material making these gas-escape routes more resistant to erosion. The change in color of the deposit marks a change in the chemistry of the erupted rocks. The lighter-colored basal rhyodacitic pumice is overlain by gray andesitic scoria.

Photo by Lee Siebert, 1972 (Smithsonian Institution).
The 8 x 10 km wide Crater Lake caldera, one of the most spectacular features of the Cascade Range, was formed about 6850 years ago during one of the world's largest Holocene eruptions. This eruption resulted in the collapse of ancestral Mount Mazama, a complex of overlapping stratovolcanoes and shield volcanoes. This view from the east shows Mount Scott, one of the pre-caldera stratovolcanoes, in the right foreground. A post-caldera cone, Wizard Island, rises above the far lake surface.

Photo by Peter Lipman, 1981 (U.S. Geological Survey).
The spectacular 8 x 10 km wide Crater Lake caldera was formed about 6850 years ago when Mount Mazama, a complex of overlapping shield volcanoes and stratovolcanoes, collapsed following a major explosive eruption. The eruption blanketed a huge area with ash falls and produced pyroclastic flows that swept all sides of the volcano. The caldera, seen here from its southern rim, is 1200 m deep and filled to half its depth by the intensely blue waters of Crater Lake.

Photo by Dave Wieprecht, 1995 (U.S. Geological Survey).
Wizard Island, a post-caldera cone of Crater Lake caldera, erupted some 300 years after formation of the caldera about 6850 years ago. The Wizard Island cinder cones rises over 200 m above the surface of the lake. A lava flow from a vent on its NW flank forms the peninsula at the left. Llao Rock, a massive lava flow erupted about 150 years prior to formation of Crater Lake caldera, forms the prominent peak on the caldera rim.

Photo by Dave Wieprecht, 1995 (U.S. Geological Survey).
The remarkably deep blue waters of Crater Lake form one of the scenic highlights of the Pacific Northwest. Mid-19th century prospectors, the first European descendants to see the lake, were struck by its intense color and named it Deep Blue Lake. The 600-m-deep lake fills half the height of a caldera that formed during a major eruption about 6850 years ago. Snow mantles the summit of Wizard Island cinder cone in the foreground and Mount Scott, a pre-caldera stratovolcano beyond the east caldera rim.

Photo by Lee Siebert, 1997 (Smithsonian Institution).
Wizard Island cinder cone, its summit mantled by an early Autumn snowfall, is the most prominent of the post-caldera cones of Crater Lake. Wizard Island grew near the western structural margin of the caldera about 6700 years ago during the final stages of lake filling. The cinder cone and visible lava flows were erupted subaerially; lake waters have risen to cover troughs on the surface of the lava flow forming the peninsula in the foreground on the NW side of the cone.

Photo by Lee Siebert, 1997 (Smithsonian Institution).
The spires of Phantom Ship, which appears to sail the deep-blue waters of Crater Lake, are eroded remnants of resistant dikes. These dikes were feeders for lavas of Phantom Cone, the oldest of the pre-collapse volcanoes forming Mount Mazama. Phantom Cone lavas have been dated at about 400,000 years before present and are exposed in the SE wall of Crater Lake caldera.

Photo by Lee Siebert, 1997 (Smithsonian Institution)
Hillman Peak, the westernmost andesitic stratovolcano of Mount Mazama, is partially dissected by Crater Lake caldera. The base of the cone consists of thin andesitic lava flows; these are overlain by bedded pyroclastic-fall deposits. The upper part of the cone, seen here, consists of andesitic lava flows erupted about 67,000 years ago. The snow-capped peak on the center horizon to the north is Mount Thielsen, a Pleistocene volcano north of Crater Lake.

Photo by Lee Siebert, 1997 (Smithsonian Institution)
The inconspicuous snow-mantled peaks on the northern horizon are the remnants of Mount Mazama, seen here from the summit of Mt. McLoughlin. Mount Mazama, a complex of overlapping stratovolcanoes and shield volcanoes that was once one of Oregon's largest volcanoes, collapsed about 6850 years ago, forming the 8 x 10 km Crater Lake caldera. The highest peak at the right is Mount Scott, part of a pre-caldera volcano east of the caldera rim. The western rim is left of the sharp-peaked Mt. Thielsen, an older volcano north of Crater Lake.

Photo by Lee Siebert, 1998 (Smithsonian Institution)
Snow-capped Wizard Island is the only one of three post-caldera cones of Crater Lake caldera that rises above the lake surface. The symmetrical Wizard Island cinder cone, capped by a 90-m-wide summit crater, formed several hundred years after the collapse of Mount Mazama about 6850 years ago. Much of the cone, which was constructed along the western structural margin of the caldera, lies beneath the 600-m-deep waters of Crater Lake. A small dome is located on a sublacustral platform east of Wizard Island.

Photo by Lee Siebert, 1997 (Smithsonian Institution).
Volcanoes form some of Earth's most spectacular scenery and have been designated as national parks in many countries. The natural landscapes in these parks are a source of visual inspiration and varied recreational opportunities and can also provide economic benefit to surrounding communities. Crater Lake National Park in the Oregon Cascade Range was established in 1902. This image looks across to Wizard Island and the western caldera rim from near the park visitor center and the Crater Lake Lodge.

Photo by Lee Siebert, 1997 (Smithsonian Institution)

The following references have all been used during the compilation of data for this volcano, it is not a comprehensive bibliography. Discussion of another volcano or eruption (sometimes far from the one that is the subject of the manuscript) may produce a citation that is not at all apparent from the title.

Bacon C R, 1983. Eruptive history of Mount Mazama and Crater Lake caldera, Cascade Range, U S A. J Volc Geotherm Res, 18: 57-116.

Bacon C R, 2008. Geologic map of Mount Mazama and Crater Lake caldera, Oregon. U S Geol Surv Sci Invest Map, I-2832, 1:24,000 scale, 4 sheets and 45 p text.

Bacon C R, Druitt T H, 1988. Compositional evolution of the zoned calcalkaline magma chamber of Mount Mazama, Crater Lake, Oregon. Contr Mineral Petr, 98: 224-256.

Bacon C R, Lanphere M A, 2006. Eruptive history and geochronology of Mount Mazama and the Crater Lake region, Oregon. Geol Soc Amer Bull, 118: 1331-1359.

Green J, Short N M, 1971. Volcanic Landforms and Surface Features: a Photographic Atlas and Glossary. New York: Springer-Verlag, 519 p.

Hildreth W E, 2007. Quaternary magmatism in the Cascades--geologic perpectives. U S Geol Surv Prof Pap, 1744: 1-125.

Kamata H, Suzuk-Kamata K, Bacon C R, 1993. Deformation of the Wineglass Welded Tuff and the timing of caldera collapse at Crater Lake, Oregon. J Volc Geotherm Res, 56: 253-266.

Nelson C H, Bacon C R, Robinson S W, Adam D P, Bradbury J P, Barber J H Jr, Schwartz D, Vagenas G, 1994. The volcanic, sedimentologic, and paleolimnologic history of the Crater Lake caldera floor, Oregon: evidence for small caldera evolution. Geol Soc Amer Bull, 106: 684-704.

Sherrod D R, Smith J G, 1990. Quaternary extrusion rates of the Cascade Range, northwestern United States and southern British Columbia. J Geophys Res, 95: 19,465-19,474.

Williams H, 1942. The geology of Crater Lake National Park, Oregon. Carnegie Inst Wash Pub, 540: 1-162.

Zdanowicz C M, Zielinski G A, Germani M S, 1999. Mount Mazama eruption: calendrical age verified and atmospheric impact assessed. Geology, 27: 621-624.

Volcano Types

Caldera
Stratovolcano(es)
Lava dome(s)
Pyroclastic cone(s)

Tectonic Setting

Subduction zone
Continental crust (> 25 km)

Rock Types

Major
Dacite
Andesite / Basaltic Andesite
Minor
Basalt / Picro-Basalt

Population

Within 5 km
Within 10 km
Within 30 km
Within 100 km
52
52
366
272,674

Affiliated Databases

Large Eruptions of Crater Lake Information about large Quaternary eruptions (VEI >= 4) is cataloged in the Large Magnitude Explosive Volcanic Eruptions (LaMEVE) database of the Volcano Global Risk Identification and Analysis Project (VOGRIPA).
WOVOdat WOVOdat is a database of volcanic unrest; instrumentally and visually recorded changes in seismicity, ground deformation, gas emission, and other parameters from their normal baselines. It is sponsored by the World Organization of Volcano Observatories (WOVO) and presently hosted at the Earth Observatory of Singapore.
EarthChem EarthChem develops and maintains databases, software, and services that support the preservation, discovery, access and analysis of geochemical data, and facilitate their integration with the broad array of other available earth science parameters. EarthChem is operated by a joint team of disciplinary scientists, data scientists, data managers and information technology developers who are part of the NSF-funded data facility Integrated Earth Data Applications (IEDA). IEDA is a collaborative effort of EarthChem and the Marine Geoscience Data System (MGDS).
Smithsonian Collections Search the Smithsonian's NMNH Department of Mineral Sciences collections database. Go to the "Search Rocks and Ores" tab and use the Volcano Name drop-down to find samples.