Trident

Photo of this volcano
  • 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
    Elevation

  • Volcano
    Number

Most Recent Bulletin Report: December 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 Contacts: 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 Global Volcanism Program has no Weekly Reports available for Trident.

Bulletin Reports - Index


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




Information is preliminary and subject to change. All times are local (unless otherwise noted)


December 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 Contacts: 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.

Eruptive History


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 Jul 2 (?) ± 182 days Unknown Confirmed 0 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.

Photo Gallery


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).
See title for photo information.

Smithsonian Sample Collections Database


The following 6 samples associated with this volcano can be found in the Smithsonian's NMNH Department of Mineral Sciences collections. Catalog number links will open a window with more information.

Catalog Number Sample Description
NMNH 117233-92 Volcanic
NMNH 117233-93 Volcanic
NMNH 117233-94 Pumice
NMNH 117233-95 Volcanic ash
NMNH 117233-97 Dacite
NMNH 117233-98 Dacite

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