Report on Trident (United States) — 1 March-7 March 2023
Smithsonian Institution / US Geological Survey
Weekly Volcanic Activity Report, 1 March-7 March 2023
Managing Editor: Sally Sennert.
Please cite this report as:
Global Volcanism Program, 2023. Report on Trident (United States) (Sennert, S, ed.). Weekly Volcanic Activity Report, 1 March-7 March 2023. Smithsonian Institution and US Geological Survey.
58.236°N, 155.1°W; summit elev. 1864 m
All times are local (unless otherwise noted)
AVO reported that the earthquake swarm at Trident was ongoing during 1-7 March. Daily small earthquakes with magnitudes less than 1 were recorded at a rate of about 1-5 per day. The Aviation Color Code remained at Yellow (the second lowest level on a four-color scale) and the Volcano Alert Level remained at Advisory (the second lowest level on a four-level scale).
Geological Summary. 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.