Report on Cayambe (Ecuador) — 14 September-20 September 2005
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 14 September-20 September 2005
Managing Editor: Gari Mayberry
Please cite this report as:
Global Volcanism Program, 2005. Report on Cayambe (Ecuador). In: Mayberry, G (ed.), Weekly Volcanic Activity Report, 14 September-20 September 2005. Smithsonian Institution and US Geological Survey.
0.029°N, 77.986°W; summit elev. 5790 m
All times are local (unless otherwise noted)
During 16-18 September, a cluster of 330 small earthquakes occurred at Cayambe. The earthquakes reached a maximum magnitude of 3.6. They occurred on the volcano's SW flank, where previous clusters had been located. The cluster had not reached the level of one that took place in March of 2004. IG reported that these types of clusters occur fairly regularly at Cayambe and could be related to changes in the internal pressure of the volcano. The earthquakes continued through at least 19 September.
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.