Report on Guagua Pichincha (Ecuador) — 27 December-2 January 2001
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 27 December-2 January 2001
Managing Editor: Gari Mayberry
Please cite this report as:
Global Volcanism Program, 2000. Report on Guagua Pichincha (Ecuador). In: Mayberry, G (ed.), Weekly Volcanic Activity Report, 27 December-2 January 2001. Smithsonian Institution and US Geological Survey.
0.171°S, 78.598°W; summit elev. 4784 m
All times are local (unless otherwise noted)
The IG reported that in comparison to November the number of long-period earthquakes, which has been shown at Guagua Pichincha to reflect the amount of lava dome growth, and the number of rockfalls decreased in December. Activity has remained relatively constant, with a daily average of 514 earthquakes.
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.