Mammoth Mountain
Find U.S. Volcano
Mammoth Mountain is a 3,369-m (11,053 ft) high lava-dome complex on the southwest topographic rim of Long Valley Caldera. It is considered to represent a magmatic system distinct from Long Valley Caldera and the Mono-Inyo Craters.
Quick Facts
Location: California, Mono County
Latitude: 37.631° N
Longitude: 119.032° W
Elevation: 3,369 (m) 11,053 (f)
Volcano type: lava domes
Composition: trachydacite
Most recent eruption: 700 years ago (phreatic)
Nearby towns: Mammoth Lakes
Threat Potential: Moderate*
*based on the National Volcano Early Warning System
Summary
Eruptions at Mammoth Mountain occurred from 100,000 to 50,000 years ago. Mammoth Mountain is surrounded by at least 35 mafic vents that are part of the same magmatic system and include Red Cones, two closely spaced basaltic cinder cones located southwest of Mammoth Mountain and southeast of Devils Postpile National Monument. The cones, whose name derives from colorful mantling scoria deposits, are unglaciated and were radiocarbon dated at about 8,000 years ago. Phreatic eruptions, distinct from those at South Inyo Craters, took place about 700 years ago from vents on the north side of Mammoth Mountain. Recent volcanic unrest, including seismicity, gas emission, and tree kill, is thought to be related to a dike intrusion beneath Mammoth Mountain in 1989. Both Long Valley Caldera and Mammoth Mountain have experienced episodes of heightened unrest over the last few decades (earthquakes, ground uplift, and/or volcanic gas emissions). As a result, the USGS manages a dense array of field sensors providing the real-time data needed to track unrest and assess hazards.
News
Unpacking CalVO's new seismic monitoring boxes
Geologic maps lay the foundation for this virtual tour of western states volcanoes.
What's Under Long Valley? Water, Heat, and Molten Rock!
Publications
California’s exposure to volcanic hazards
The potential for damaging earthquakes, landslides, floods, tsunamis, and wildfires is widely recognized in California. The same cannot be said for volcanic eruptions, despite the fact that they occur in the state about as frequently as the largest earthquakes on the San Andreas Fault. At least ten eruptions have taken place in the past 1,000 years, and future volcanic eruptions are inevitable.The
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
The California Volcano Observatory: Monitoring the state's restless volcanoes
Volcanic eruptions happen in the State of California about as frequently as the largest earthquakes on the San Andreas Fault Zone. At least 10 eruptions have taken place in California in the past 1,000 years—most recently at Lassen Peak in Lassen Volcanic National Park (1914 to 1917) in the northern part of the State—and future volcanic eruptions are inevitable. The U.S. Geological Survey Californ
