Report on Santa Maria (Guatemala) — November 1986
Scientific Event Alert Network Bulletin, vol. 11, no. 11 (November 1986)
Managing Editor: Lindsay McClelland.
Santa Maria (Guatemala) Lateral blast and pyroclastic flow on S flank
Please cite this report as:
Global Volcanism Program, 1986. Report on Santa Maria (Guatemala) (McClelland, L., ed.). Scientific Event Alert Network Bulletin, 11:11. Smithsonian Institution.
14.757°N, 91.552°W; summit elev. 3745 m
All times are local (unless otherwise noted)
A lateral blast and pyroclastic flow occurred on 1 December at 1330, damaging 2.5 km2 of vegetation on the S flank. Ash clouds reached 3,600 m height and up to 5 cm of ash were deposited. Three new fumaroles appeared on the S flank.
Newspapers reported that debris from the eruption blocked two rivers and caused floods in several villages. Many families were evacuated. Explosions, increased seismic activity, and continuing lava flow from the crater were reported on the day of the eruption.
Geologic Background. Symmetrical, forest-covered Santa María volcano is part of a chain of large stratovolcanoes that rise above the Pacific coastal plain of Guatemala. The sharp-topped, conical profile is cut on the SW flank by a 1.5-km-wide crater. The oval-shaped crater extends from just below the summit to the lower flank, and was formed during a catastrophic eruption in 1902. The renowned Plinian eruption of 1902 that devastated much of SW Guatemala followed a long repose period after construction of the large basaltic-andesite stratovolcano. The massive dacitic Santiaguito lava-dome complex has been growing at the base of the 1902 crater since 1922. Compound dome growth at Santiaguito has occurred episodically from four vents, with activity progressing W towards the most recent, Caliente. Dome growth has been accompanied by almost continuous minor explosions, with periodic lava extrusion, larger explosions, pyroclastic flows, and lahars.
Information Contacts: E. Sánchez and Edgar Quévec, INSIVUMEH; ACAN News, Panama City, Panama.