Report on Cayambe (Ecuador) — 12 November-18 November 2003
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 12 November-18 November 2003
Managing Editor: Gari Mayberry
Please cite this report as:
Global Volcanism Program, 2003. Report on Cayambe (Ecuador). In: Mayberry, G (ed.), Weekly Volcanic Activity Report, 12 November-18 November 2003. Smithsonian Institution and US Geological Survey.
0.029°N, 77.986°W; summit elev. 5790 m
All times are local (unless otherwise noted)
During 3-9 November, about nine earthquakes occurred per day at Cayambe, near the daily average since August 2003 and about twice the daily average of 4 per day before that. Seismicity also included small clusters of tectonic earthquakes with magnitudes less than 3. There were reports of a strong scent of sulfur in the sector of Picos Jarrína at an elevation of ~5,460 m. The scent was strongest near cracks.
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.