Report on Augustine (United States) — April 1976
Natural Science Event Bulletin, vol. 1, no. 7 (April 1976)
Managing Editor: David Squires.
Augustine (United States) Extensive steaming observed from aircraft
Please cite this report as:
Global Volcanism Program, 1976. Report on Augustine (United States). In: Squires, D (ed.), Natural Science Event Bulletin, 1:7. Smithsonian Institution. https://doi.org/10.5479/si.GVP.NSEB197604-313010.
59.363°N, 153.43°W; summit elev. 1252 m
All times are local (unless otherwise noted)
Passing aircraft noted extensive steaming on 23 April (1015) and 29 April (1500), but no eruptive activity was reported during the month [but see 01:08].
Geologic Background. Augustine volcano, rising above Kamishak Bay in the southern Cook Inlet about 290 km SW of Anchorage, is the most active volcano of the eastern Aleutian arc. It consists of a complex of overlapping summit lava domes surrounded by an apron of volcaniclastic debris that descends to the sea on all sides. Few lava flows are exposed; the flanks consist mainly of debris-avalanche and pyroclastic-flow deposits formed by repeated collapse and regrowth of the volcano's summit. The latest episode of edifice collapse occurred during Augustine's largest historical eruption in 1883; subsequent dome growth has restored the volcano to a height comparable to that prior to 1883. The oldest dated volcanic rocks on Augustine are more than 40,000 years old. At least 11 large debris avalanches have reached the sea during the past 1800-2000 years, and five major pumiceous tephras have been erupted during this interval. Historical eruptions have typically consisted of explosive activity with emplacement of pumiceous pyroclastic-flow deposits followed by lava dome extrusion with associated block-and-ash flows.
Information Contacts: J. Kienle, Univ. of Alaska.