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  • United States
  • Alaska
  • Stratovolcano
  • 1974 CE
  • Country
  • Volcanic Region
  • Primary Volcano Type
  • Last Known Eruption
  • 58.236°N
  • 155.1°W

  • 1864 m
    6114 ft

  • 312160
  • Latitude
  • Longitude

  • Summit

  • Volcano

The Global Volcanism Program has no activity reports for Trident.

The Global Volcanism Program has no Weekly Reports available for Trident.

Index of Monthly Reports

Reports are organized chronologically and indexed below by Month/Year (Publication Volume:Number), and include a one-line summary. Click on the index link or scroll down to read the reports.

12/1968 (CSLP 61-68) Large earthquakes and extensive ashfall observed; lava plug destroyed

Contents of Monthly Reports

All information contained in these reports is preliminary and subject to change.

12/1968 (CSLP 61-68) Large earthquakes and extensive ashfall observed; lava plug destroyed

Card 0276-0277 (09 December 1968) Ashfall covering snow extends 60 miles

"On November 21, beginning at approximately 2100Z, an extensive low-level reconaissance was performed by this agancy in a Cessna 180 aircraft. Our immediate route to the coastal area disclosed a light ash cover extending to the NW of Mount Trident. An investigation of this ash cover, on top of snow, revealed that it did originate from Mount Trident and extended for a distance of approximately 60 miles and had a fan width of approximately three miles at its termini. Medium-sized bombs were observed for an estimated radius of 1/2 mile around the cone. Mt. Trident was completely clear of its usually prominent plug. There was no sign of a recent lava flow. Smoke and steam were not an obstruction. A series of 35 mm color slides were taken of the Mount Trident cone, showing clearly the absence of the plug. Dated photographs, showing the presence and absence of the plug are on file. It is impossible to ascertain the exact period of this outburst, but it could appropriately be narrowed to the immediate 14 days preceeding the date of observation.

"The continued reconnaisance of Cape Douglas revealed no sign of surface disturbance; snow ridges were intact and no other indications of activity were discovered. The coastal beaches did appear to have suffered from an extremely high water disturbance within the recent couple of days. Driftwood was unusually high and a large amount of sea life was observed stranded. Starfish, clams, and scallops were abundant."

Card 0295-0296 (16 December 1968) Six relatively large earthquakes during 11-29 November

"The seismic telemeter network has recorded several relatively large earthquakes in the area of the Katmai National Monument during the month of November. Dates and magnitudes are as follows: 11 November, M 4.0; 20 November, M 5.1; 21 November, M 3.6; 23 November, M 4.8; 27 November, M 4.8; 29 November, M 3.9. We only locate shocks if the P-arrivals are clearly seen on three stations of the network; however, numerous smaller quakes with S-P times of the right order have been seen on the Big Mountain (BIG) and Sparevohn (SVW) stations during October. Roland Johnson from our Institute reported a very strong infrasonic signal on the 14th of November approaching the Fairbanks array system from 208°E of north (the direction from the Katmai area) at 0406 GMT. The seismic network recorded an earthquake at 0335 in SVW only with about the correct S-P time for the Katmai area (the closer station, BIG, was disconnected at that time)."

Information Contact:
Card 0276-0277 (09 December 1968) Thomas E. Atwood, Ranger-in-Charge, Katmai National Monument, King Salmon AK, USA.
Card 0295-0296 (16 December 1968) Ed Berg, Geophysical Institute, University of Alaska, College AK, USA.

The Trident stratovolcano cluster was named for the three prominent peaks that were the most visible features at the summit prior to 1953. The andesitic-dacitic group consists of four overlapping stratovolcanoes and numerous flank lava domes, including Falling Mountain and Mt. Cerberus on the far west flank. The summit complex is located 3-5 km SE of Novarupta volcano, and merges along a ridge to the NE with Katmai. The three oldest Trident volcanoes are glaciated and Pleistocene in age, while the youngest, Southwest Trident, was formed during historical time. Eruptions migrated through time from the NE to the SW. In 1953 a new lava dome began growing on the SW flank of Trident I volcano. A series of thick andesitic lava flows were erupted between 1953 and 1968, forming a cone with 400-800 m of local relief. Periodic explosions took place until 1974, and the current summit contains a 350-m-wide crater. Some of the distal lava flows from West Trident stratovolcano collapsed into the Novarupta vent during its 1912 eruption.

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

Start Date Stop Date Eruption Certainty VEI Evidence Activity Area or Unit
1974 Jul 15 ± 45 days Unknown Confirmed 3 Historical Observations SW flank
1968 Nov 13 1968 Nov 13 Confirmed 3 Historical Observations SW flank
1967 Sep 5 1968 Feb 25 Confirmed 3 Historical Observations SW flank
1966 (?) Unknown Confirmed   Historical Observations SW flank
1964 May 31 Unknown Confirmed 3 Historical Observations SW flank
1963 Oct 17 1963 Nov 17 (?) Confirmed 3 Historical Observations SW flank
1963 Apr 1 1963 Apr 3 Confirmed 3 Historical Observations SW flank
1962 Jun 9 1962 Jun 9 Confirmed 3 Historical Observations SW flank
1961 Jun 30 (?) Unknown Confirmed 2 Historical Observations SW flank (1100 m)
1957 1960 Aug 10 (?) Confirmed 2 Historical Observations SW flank
1956 Sep 8 1956 Sep 9 Confirmed 2 Unknown Volcano Uncertain: attributed to Trident
1953 Feb 15 1954 Oct 5 (?) Confirmed 3 Historical Observations SW flank (1100 m)
1950 Jul 2 1950 Aug 18 Confirmed 2 Unknown Volcano Uncertain: attributed to Trident
1949 Jun Unknown Confirmed   Historical Observations
1913 Sep Unknown Confirmed 1 Historical Observations

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
East Trident Stratovolcano 1832 m 58° 15' 0" N 155° 4' 0" W
Southwest Trident Stratovolcano 58° 14' 0" N 155° 7' 0" W
Trident I Stratovolcano 1864 m 58° 14' 0" N 155° 6' 0" W
West Trident Stratovolcano 1708 m 58° 14' 30" N 155° 8' 0" W

Feature Name Feature Type Elevation Latitude Longitude
Cerberus, Mount Dome 1098 m 58° 14' 47" N 155° 11' 56" W
Falling Mountain Dome 1160 m 58° 15' 20" N 155° 10' 19" W
Trident volcano, seen here from Baked Mountain to its NW, was initially named for its three prominent summits. A series of eruptions from 1953 until 1968 constructed a fourth cone, which forms the prominent, smoother-surfaced peak at the right. The 3 peaks of Trident at the left are overlapping, glacially eroded stratovolcanoes. As many as 23 lava domes are found on the Trident volcanic complex. Fresh, blocky andesitic lava domes radiate from the new cone on the SW flank. The 1912 Novarupta lava dome is visible at the lower center.

Photo by Game McGimsey (U.S. Geological Survey, Alaska Volcano Observatory).

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.

Coombs M L, Eichelberger J C, Rutherford M J, 2000. Magma storage and mixing conditions for the 1953-1974 eruptions of Southwest Trident volcano, Katmai National Park, Alaska. Contr Mineral Petr, 140: 99-118.

Henning R A, Rosenthal C H, Olds B, Reading E (eds), 1976. Alaska's volcanoes, northern link in the ring of fire. Alaska Geog, 4: 1-88.

Hildreth W, 1987. New perspectives on the eruption of 1912 in the Valley of Ten Tousand Smokes, Katmai National Park, Alaska. Bull Volc, 49: 680-693.

Hildreth W, Fierstein J, 2000. Katmai volcanic cluster and the great eruption of 1912. Geol Soc Amer Bull, 112: 1594-1620.

Hildreth W, Fierstein J, Lanphere M A, Siems D F, 2003a. Trident volcano: four contiguous stratocones adjacent to Katmai Pass, Alaska Peninsula. Studies by the U.S. Geological Survey in Alaska, 2001 U S Geol Surv Profl Pap, 1678: 153-180.

Hildreth W, Lanphere M A, Fierstein J, 2003b. Geochronology and eruptive history of the Katmai volcanic cluster, Alaska Peninsula. Earth Planet Sci Lett, 214: 93-114.

Miller T P, McGimsey R G, Richter D H, Riehle J R, Nye C J, Yount M E, Dumoulin J A, 1998. Catalogue of the historically active volcanoes of Alaska. U S Geol Surv Open-File Rpt, 98-582: 1-104.

Motyka R J, Liss S A, Nye C J, Moorman M A, 1993. Geothermal resources of the Aleutian arc. Alaska Div Geol Geophys Surv, Prof Rpt, no 114, 17 p and 4 map sheets.

Smith R L, Shaw H R, Luedke R G, Russell S L, 1978. Comprehensive tables giving physical data and thermal energy estimates for young igneous systems of the United States. U S Geol Surv Open-File Rpt, 78-925: 1-25.

Wood C A, Kienle J (eds), 1990. Volcanoes of North America. Cambridge, England: Cambridge Univ Press, 354 p.

Volcano Types

Pyroclastic cone(s)
Lava dome(s)

Tectonic Setting

Subduction zone
Continental crust (> 25 km)

Rock Types

Andesite / Basaltic Andesite


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

Affiliated Databases

Large Eruptions of Trident 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.