Report on Cayambe (Ecuador) — 28 December-3 January 2017
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 28 December-3 January 2017
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2016. Report on Cayambe (Ecuador). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 28 December-3 January 2017. Smithsonian Institution and US Geological Survey.
0.029°N, 77.986°W; summit elev. 5790 m
All times are local (unless otherwise noted)
On 28 December IG reported continued anomalous seismic activity at Cayambe characterized by volcano-tectonic and long-period earthquakes located 2-8 km below the summit. As many as 40 earthquakes had been recorded each day for the previous two weeks and starting on 24 December that number again increased, especially for volcano-tectonic events. A swarm on 27 December consisted of 100 small-magnitude events. A strong sulfur odor persisted, and cracks in the glacier near the summit that climbers has recently reported were visible during an overflight. In addition, deformation on the flanks was detected in GPS data.
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.