Report on Concepcion (Nicaragua) — 4 July-10 July 2007
Smithsonian Institution / US Geological Survey
Weekly Volcanic Activity Report, 4 July-10 July 2007
Managing Editor: Sally Sennert.
Please cite this report as:
Global Volcanism Program, 2007. Report on Concepcion (Nicaragua) (Sennert, S, ed.). Weekly Volcanic Activity Report, 4 July-10 July 2007. Smithsonian Institution and US Geological Survey.
11.538°N, 85.622°W; summit elev. 1700 m
All times are local (unless otherwise noted)
INETER reported that explosions in the crater of Concepción on 10 July produced ash-and-gas plumes that drifted NW. Ashfall was reported from areas downwind.
Geological Summary. Volcán Concepción is one of Nicaragua's highest and most active volcanoes. The symmetrical basaltic-to-dacitic stratovolcano forms the NW half of the dumbbell-shaped island of Ometepe in Lake Nicaragua and is connected to neighboring Madera volcano by a narrow isthmus. A steep-walled summit crater is 250 m deep and has a higher western rim. N-S-trending fractures on the flanks have produced chains of spatter cones, cinder cones, lava domes, and maars located on the NW, NE, SE, and southern sides extending in some cases down to Lake Nicaragua. Concepción was constructed above a basement of lake sediments, and the modern cone grew above a largely buried caldera, a small remnant of which forms a break in slope about halfway up the N flank. Frequent explosive eruptions during the past half century have increased the height of the summit significantly above that shown on current topographic maps and have kept the upper part of the volcano unvegetated.