Report on Chiginagak (United States) — August 1998
Bulletin of the Global Volcanism Network, vol. 23, no. 8 (August 1998)
Managing Editor: Richard Wunderman.
Chiginagak (United States) Ash, gas-and-steam plume on 13 August
Please cite this report as:
Global Volcanism Program, 1998. Report on Chiginagak (United States) (Wunderman, R., ed.). Bulletin of the Global Volcanism Network, 23:8. Smithsonian Institution. https://doi.org/10.5479/si.GVP.BGVN199808-312110.
57.135°N, 156.99°W; summit elev. 2221 m
All times are local (unless otherwise noted)
Residents of the town of Pilot Point and personnel of the U.S. Fish and Wildlife Service reported on 13 August that the usual white steaming of Chiginagak fumaroles had changed for a time. The volcano had begun to issue puffs of black ash accompanied by a greenish-yellow gas-and-steam plume that rose 150-300 m above the summit. By the following morning a dusting of black ash was observed on fresh snow on the upper part of the volcano. The plume had reverted to white steam. The activity was not substantial enough to be detected by satellite imagery. The Alaska Volcano Observatory has no seismic instruments at the site.
Geologic Background. The symmetrical, calc-alkaline Chiginagak stratovolcano located about 15 km NW of Chiginagak Bay contains a small summit crater, which is breached to the south, and one or more summit lava domes. Satellitic lava domes occur high on the NW and SE flanks of the glacier-mantled volcano. An unglaciated lava flow and an overlying pyroclastic-flow deposit extending east from the summit are the most recent products of Chiginagak. They most likely originated from a lava dome at 1687 m on the SE flank, 1 km from the summit of the volcano, which has variably been estimated to be from 2075 to 2221 m high. Brief ash eruptions were reported in July 1971 and August 1998. Fumarolic activity occurs at 1600 m elevation on the NE flank of the volcano, and two areas of hot-spring travertine deposition are located at the NW base of the volcano near Volcano Creek.
Information Contacts: Alaska Volcano Observatory (AVO), a cooperative program of a) U.S. Geological Survey, 4200 University Drive, Anchorage, AK 99508-4667, USA (URL: http://www.avo.alaska.edu/), b) Geophysical Institute, University of Alaska, PO Box 757320, Fairbanks, AK 99775-7320, USA, and c) Alaska Division of Geological & Geophysical Surveys, 794 University Ave., Suite 200, Fairbanks, AK 99709, USA.