Report on Cayambe (Ecuador) — 18 February-24 February 2004
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 18 February-24 February 2004
Managing Editor: Gari Mayberry
Please cite this report as:
Global Volcanism Program, 2004. Report on Cayambe (Ecuador). In: Mayberry, G (ed.), Weekly Volcanic Activity Report, 18 February-24 February 2004. Smithsonian Institution and US Geological Survey.
0.029°N, 77.986°W; summit elev. 5790 m
All times are local (unless otherwise noted)
On 29 January a swarm of ~148 small volcano-tectonic earthquakes occurred at Cayambe. By 1 February seismicity had decreased, reaching "normal" base levels. IG reported that the swarm may have represented an increase in the internal pressure of the volcano due to the arrival of fluid, possibly magma.
Geologic Background. The massive compound andesitic-dacitic Cayambe stratovolcano is located on the isolated western edge of the Cordillera Real, east of the Inter-Andean Valley. The volcano, whose southern flank lies astride the equator, is capped by extensive glaciers, which descend to 4200 m on the eastern Amazonian side. The modern Nevado Cayambe, constructed to the east of older Pleistocene volcanic complexes, contains two summit lava domes located about 1.5 km apart, the western of which is the highest. Several other lava domes on the upper flanks have been the source of pyroclastic flows that reached the lower flanks. A prominent Holocene pyroclastic cone on the lower E flank, La Virgen, fed thick andesitic lava flows that traveled about 10 km E. Nevado Cayambe was recently discovered to have produced frequent explosive eruptions beginning about 4000 years ago, and to have had a single historical eruption during 1785-86.