Report on Santa Maria (Guatemala) — June 1990
Bulletin of the Global Volcanism Network, vol. 15, no. 6 (June 1990)
Managing Editor: Lindsay McClelland
Santa Maria (Guatemala) Explosions feed large columns and pyroclastic flow
Please cite this report as:
Global Volcanism Program, 1990. Report on Santa Maria (Guatemala). In: McClelland, L (ed.), Bulletin of the Global Volcanism Network, 15:6. Smithsonian Institution. http://dx.doi.org/10.5479/si.GVP.BGVN199006-342030.
14.757°N, 91.552°W; summit elev. 3745 m
All times are local (unless otherwise noted)
A series of strong explosions that began at about 1030 on 13 July sent eruption clouds to 7.5 km. Vigorous explosive activity continued until the next morning, depositing as much as 4 cm of ash, mostly S-SW of the vent. Geologists calculated a preliminary ash volume of 2.6 x 105 m3. Damage from ashfall was minimal. A pyroclastic flow extended 6.5 km down the Nimá II valley, generating a large vapor cloud where it encountered river water. An overflight on 17 July revealed that the pyroclastic flow deposit had not dammed the river, a possibility that had concerned hazard officials. Smaller explosions typical of Santiaguito's long-term eruption continued after the end of the vigorous activity. Eight explosions were recorded on 14 July, the largest producing a cloud that reached about 3,000 m above sea level (roughly 500 m above the dome's summit); the other 7 were of relatively low energy. Four low-energy explosions were recorded on the 17th.
Geologic Background. Symmetrical, forest-covered Santa María volcano is one of the most prominent of a chain of large stratovolcanoes that rises dramatically above the Pacific coastal plain of Guatemala. The 3772-m-high stratovolcano has a sharp-topped, conical profile that is cut on the SW flank by a large, 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 westward-younging vents, the most recent of which is 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 Otoniel Matías, INSIVUMEH.