Deschutes & Ochoco National Forests
Crooked River National Grassland

Oregon Volcanoes

Mt. Mazama Volcano

SUMMARY

Type: stratovolcano with caldera
Activity: dormant
Last Eruption: about 7,700 yrs ago
Rock Type: basalt to rhyodacite
Eruptive Volume: 130 cu km
Latitude: 42.94 N
Longitude: 122.10 W
Location Maps: from TIGER Mapping Service

• State Level - shows state and communities
• County Level - shows county lines, highways, and communities
• Local Level - shows above plus lakes and local roads

Topo Map from TopoZone

Mt. Mazama Volcano (Crater Lake) Photo Menu

GEOLOGIC BACKGROUND:

Crater Lake partially fills a caldera that formed by collapse of a 12,000 foot volcano known as Mount Mazama during an enormous pyroclastic eruption approximately 7,700 calendar years ago (6,845 C14 yrs B.P.). The caldera-forming eruption of Mount Mazama changed the landscape all around the volcano. Pyroclastic flows devastated the surrounding area, including all of the river valleys that drained Mount Mazama to as far as 70 km away, and a blanket of pumice and ash fell to the northeast of the volcano at least as far as southern Canada. Prior to the climactic event, Mount Mazama had a 400,000 year history of activity more like that of other Cascade volcanic centers such as Mount Shasta. Since the climactic eruption, there have been several less violent, smaller postcaldera eruptions within the caldera itself. 

HISTORIC ACTIVITY:

• None

DATA SOURCE:

• USGS
  

ADDITIONAL INFORMATION

• Link to U.S.G.S. - CVO's Mt. Mazama Volcano Info
• Link to U.S.G.S. Visit a Volcano Info for Crater Lake
• Link to Volcano World's Mt. Mazama Volcano Info
• Link to Crater Lake National Park