Mammoth Mountain

Photo of this volcano
Google Earth icon
  Google Earth Placemark with Features
  • Country
  • Volcanic Region
  • Primary Volcano Type
  • Last Known Eruption
  • 37.631°N
  • 119.032°W

  • 3369 m
    11050 ft

  • 323150
  • Latitude
  • Longitude

  • Summit

  • Volcano

The Global Volcanism Program has no activity reports for Mammoth Mountain.

The Global Volcanism Program has no Weekly Reports available for Mammoth Mountain.

The Global Volcanism Program has no Bulletin Reports available for Mammoth Mountain.

Basic Data

Volcano Number

Last Known Eruption



1260 CE

3369 m / 11050 ft


Volcano Types

Lava dome(s)
Pyroclastic cone(s)

Rock Types

Trachyte / Trachyandesite
Trachybasalt / Tephrite Basanite
Trachyandesite / Basaltic trachy-andesite
Basalt / Picro-Basalt

Tectonic Setting

Rift zone
Continental crust (> 25 km)


Within 5 km
Within 10 km
Within 30 km
Within 100 km

Geological Summary

Mammoth Mountain, a trachydacitic lava-dome complex, lies on the SW topographic rim of Long Valley caldera. The 3369-m-high volcano lies west of the structural rim of the caldera and is considered to represent a magmatic system distinct from Long Valley caldera and the Inyo Craters (Hildreth, 2004). The latest magmatic eruptions at Mammoth Mountain took place about 57,000 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 SW of Mammoth Mountain and SE of Devils Postpile National Monument. The cones, whose name derives from colorful mantling scoria deposits, are unglaciated and were radiocarbon dated at about 8900 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 unrest, including seismicity, gas emission, and tree kill, is thought to be related to dike intrusion beneath Mammoth Mountain in 1989.


The following references have all been used during the compilation of data for this volcano, it is not a comprehensive bibliography.

Browne B, Bursik M, Deming J, Louros M, Martos A, Stine S, 2010. Eruption chronology and petrologic reconstruction of the ca. 8500 yr B.P. eruption of Red Cones, southern Inyo chain, California. Geol Soc Amer Bull, 122: 1401-1422.

Bursik M, 2002-. Long Valley tephra database.

Hildreth W, 2004. Volcanological perspectives on Long Valley, Mammoth Mountain, and Mono Craters: several contiguous but discrete systems. J Volc Geotherm Res, 136: 169-198.

Hill D P, Prejean S, 2005. Magmatic unrest beneath Mammoth Mountain, California. J Volc Geotherm Res, 146: 257-283.

Huber N K, Eckhardt W W, 1985. Devils Postpile story. Sequoia Nat Hist Assoc, 30 p.

Huber N K, Rinehart C D, 1967. Cenozoic volcanic rocks of the Devils Postpile quadrangle, eastern Sierra Nevada California. U S Geol Surv Prof Pap, 554-D: 1-21.

Miller C D, 1989. Potential hazards from future volcanic eruptions in California. U S Geol Surv Bull, 1847: 1-17.

Sorey M L, Evans W C, Kennedy B M, Farrar C D, Hainsworth L J, Hausback B, 1998. Carbon dioxide and helium emissions from a reservoir of magmatic gas beneath Mammoth Mountain, California. J Geophys Res, 103: 15,303-15,323.

Eruptive History

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

Start Date Stop Date Eruption Certainty VEI Evidence Activity Area or Unit
1260 ± 40 years Unknown Confirmed   Radiocarbon (corrected) North flank of Mammoth Mountain
6960 BCE ± 500 years Unknown Confirmed 2 Radiocarbon (uncorrected) SSW of Mammoth Mtn (Red Cones)

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.


Feature Name Feature Type Elevation Latitude Longitude
Red Cones Pyroclastic cone 2748 m 37° 35' 0" N 119° 3' 0" W


Feature Name Feature Type Elevation Latitude Longitude
Earthquake Dome Dome 2860 m 37° 40' 0" N 119° 0' 0" W
Mammoth Knolls Dome 2660 m 37° 40' 0" N 118° 59' 0" W

Photo Gallery

In 1995 soil gas fluctuations caused tree dieback at Horseshoe Lake on the SE side of Mammoth Mountain. A period of unrest including uplift and seismic swarms has continued for more than a decade.

Photo by Dave Wieprecht, 1995 (U.S. Geological Survey).
Mammoth Mountain rises to the SE of Minaret Summit. The 3369-m-high volcano formed between about 111,000 and 57,000 years ago and consists of a series of trachydacitic and rhyodacitic lava flows and lava domes. Magmatic activity at Mammoth Mountain overlapped the latest eruptions of the Long Valley caldera and ended prior to the onset of eruptions at the Mono-Inyo chain, although phreatic eruptions on the northern flank of Mammoth Mountain took place during the Holocene.

Photo by Lee Siebert, 1998 (Smithsonian Institution).
Water partially fills a phreatic crater formed on the northern flank of Mammoth Mountain, the snow-covered peak in the background. This and other nearby craters were formed by explosive eruptions about 700 years ago that were distinct from nearby eruptions at the southern end of the Inyo Craters. The Mammoth Mountain craters, some of which lie within the Mammoth Mountain ski area, are oriented NW-SE at the northern base of Mammoth Mountain.

Photo by Lee Siebert, 1998 (Smithsonian Institution).
An area of extensive tree kill at Horseshoe Lake, SE of Mammoth Mountain, is seen in July 1998. Dead trees on the NW side of the lake contrast with undamaged trees on the opposite side of the lake. The Horseshoe Lake area is the largest of seven areas of elevated carbon dioxide concentrations located on the southern, northern, and western flanks of Mammoth Mountain. Trees began taking up of magmatic carbon dioxide in early 1990 following the 1989 Mammoth Mountain earthquake swarm.

Photo by Lee Siebert, 1998 (Smithsonian Institution).
Red Cones, here mantled in winter white in a telephoto view looking SW from Mammoth Mountain, are two young basaltic cinder cones in the eastern Sierra Nevada Mountains near Devils Postpile National Monuement. The youthful-looking cones are Holocene in age.

Photo by Paul Kimberly, 1997 (Smithsonian Institution).
Red Cones, two closely spaced basaltic cinder cones SW of Mammoth Mountain, near Devils Postpile National Monument, are youthful unglaciated cones that were erupted about 8900 years ago. The two breached cones fed lava flows that joined to form a flow 2 km long and 2 km wide. The southern cone is seen here from the flanks of the northern cone. The reddish oxidized scoria of both cones is mantled by light-colored pumice erupted from the Inyo Craters about 650 years ago, visible here at the base of the northern cone.

Photo by Lee Siebert, 1998 (Smithsonian Institution)
Mammoth Mountain, a Pleistocene trachydacitic lava-dome complex constructed on the SW topographic rim of the Long Valley caldera between about 200,000 and 50,000 years ago, forms the broad peak on the horizon. The Red Cones (center and lower left) are part of series of about three dozen mafic cones surrounding Mammoth Mountain. The oxidized reddish scoria of the cone, which was formed during the early Holocene, is mantled at its base by light-colored pumice erupted from the Inyo Craters about 650 years ago.

Photo by Lee Siebert, 1998 (Smithsonian Institution)
The rugged Sierra Nevada mountain range rises beyond the reddish rim of the southern cone of the twin Red Cones. The southern cone is breached to the NW and fed a lava flow that joined with one erupted from the SW breach of the northern cone to form a flow 2 km long and 2 km wide that traveled west to Crater Creek. Devils Postpile National Monument, with its spectacular columnar-jointed basaltic lava flow, lies along the Middle Fork of the San Joaquin River, below the rugged Minarets and Banner Peak on the horizon.

Photo by Lee Siebert, 1998 (Smithsonian Institution)

Smithsonian Sample Collections Database

There are no samples for Mammoth Mountain in the Smithsonian's NMNH Department of Mineral Sciences Rock and Ore collection.

Affiliated Sites

Large Eruptions of Mammoth Mountain 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).
MODVOLC - HIGP MODIS Thermal Alert System Using infrared satellite Moderate Resolution Imaging Spectroradiometer (MODIS) data, scientists at the Hawai'i Institute of Geophysics and Planetology, University of Hawai'i, developed an automated system called MODVOLC to map thermal hot-spots in near real time. For each MODIS image, the algorithm automatically scans each 1 km pixel within it to check for high-temperature hot-spots. When one is found the date, time, location, and intensity are recorded. MODIS looks at every square km of the Earth every 48 hours, once during the day and once during the night, and the presence of two MODIS sensors in space allows at least four hot-spot observations every two days. Each day updated global maps are compiled to display the locations of all hot spots detected in the previous 24 hours. There is a drop-down list with volcano names which allow users to 'zoom-in' and examine the distribution of hot-spots at a variety of spatial scales.
MIROVA Middle InfraRed Observation of Volcanic Activity (MIROVA) is a near real time volcanic hot-spot detection system based on the analysis of MODIS (Moderate Resolution Imaging Spectroradiometer) data. In particular, MIROVA uses the Middle InfraRed Radiation (MIR), measured over target volcanoes, in order to detect, locate and measure the heat radiation sourced from volcanic activity.