Mount Trident
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| Mount Trident | |
|---|---|
 Multiple peaks of Mount Trident, from the top of Baked Mountain, Valley of the Ten Thousand Smokes. |
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| Elevation | 6,115 feet (1,864 metres) |
| Location | Alaska, USA |
| Range | Kejulik Mountains |
| Coordinates | |
| Topo map | USGS Mount Katmai A-4 |
| Type | Stratovolcano |
| Last eruption | 1975 |
- For the mountain in Antarctica, see Mount Trident (Antarctica).
Mount Trident is an eroded volcanic complex consisting of numerous domes (up to 23), as high as 1864 m in elevation, along a northeast-southwest oriented volcanic front on the Pacific Ocean side of the Alaska Peninsula. A new dome was emplaced beginning in 1953 at an altitude of 1097 m in an amphitheater on the southwest flank of the southwest peak.
[edit] Historical volcanic activity
There is no evidence of recent eruptive activity at the summit of Trident, nor have there been any reports of historical activity, except fumarolic activity on the east side. The earliest known activity were minor eruptions in 1913, 1949 and 1950. A satellite cone formed February 15, 1953 on the southwest flank of Mt. Trident following a major explosive eruption that sent ash to an altitude of over 9 km (5.6 mi). A succession of blocky lava flows were erupted in 1954, 1957, 1958, 1959-1960 from the new vent. Ash eruptions, some to altitudes over 12 km, were associated with several of the lava eruptions. By 1960, the dome had grown nearly 260 m (853 ft) high and a sequence of viscous flows, up to 300 m (984 ft) thick and covering an area of 5 km2 south of the volcano, had been extruded. Further explosions were reported in the early to late 1960s. Lava extrusion, accompanied by explosions were also reported from 1966 to 1968 and 1974 to 1975. In 1983, steam and/or vapor continued to rise from the central vent area of the new cone as well as from numerous fumaroles on the near-vent portion of the blocky lava flows.
[edit] Composition
Trident lavas are andesitic to dacitic in composition. The dominant phenocrysts are zoned plagioclase, hypersthene, calcic clinopyroxene, titanomagnetite, and rimmed olivine. The five flows erupted from the new vent during 1953-1963 are olivine-bearing, two pyroxene, high-silica andesite.
