Report on Guagua Pichincha (Ecuador) — 8 February-14 February 2006
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 8 February-14 February 2006
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2006. Report on Guagua Pichincha (Ecuador). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 8 February-14 February 2006. Smithsonian Institution and US Geological Survey.
0.171°S, 78.598°W; summit elev. 4784 m
All times are local (unless otherwise noted)
On 5 February, beginning around 1300, three small gas emissions occurred at Guagua Pichincha. IG reported that this phreatic activity was associated with accumulated rainfall that was heated by magmatic material from the previous eruptive period, and was not related to renewed volcanic activity. After the emissions, a series of seismic signals associated with rockfalls and long-period earthquakes were recorded. The signals were related to degassing that commonly occurs after emissions. Cloudy conditions prevented observations of the volcano. IG recommended that people should not visit Guagua Pichincha's crater since emissions or explosions can occur at any time.
Geologic Background. Guagua Pichincha and the older Pleistocene Rucu Pichincha stratovolcanoes form a broad volcanic massif that rises immediately to the W of Ecuador's capital city, Quito. A lava dome is located at the head of a 6-km-wide breached caldera that formed during a late-Pleistocene slope failure ~50,000 years ago. Subsequent late-Pleistocene and Holocene eruptions from the central vent in the breached caldera consisted of explosive activity with pyroclastic flows accompanied by periodic growth and destruction of the central lava dome. One of Ecuador's most active volcanoes, it is the site of many minor eruptions since the beginning of the Spanish era. The largest historical eruption took place in 1660, when ash fell over a 1000 km radius, accumulating to 30 cm depth in Quito. Pyroclastic flows and surges also occurred, primarily to then W, and affected agricultural activity, causing great economic losses.