Report on Chiles-Cerro Negro (Colombia-Ecuador) — 22 October-28 October 2014
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 22 October-28 October 2014
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2014. Report on Chiles-Cerro Negro (Colombia-Ecuador). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 22 October-28 October 2014. Smithsonian Institution and US Geological Survey.
0.817°N, 77.938°W; summit elev. 4698 m
All times are local (unless otherwise noted)
Based on reports from Observatorio Vulcanológico and Sismológico de Pasto (SGC-OVSP), and the Instituto Geofísico de la Escuela Politécnica Nacional (IGEPN), on 26 October Servicio Geológico Colombiano (SGC) stated that seismic activity at Cerro Negro de Mayasquer and Chiles volcanoes continued at a high rate. Since 29 September 2014 about 81,000 earthquakes had been detected with 6,300 of those events occurring on 25 October. The epicenter was 2-3.5 km S of Chiles. Interferometry (INSAR) and a high resolution GPS network both showed localized deformation S of Chiles. The Alert Level remained at Orange (level 3 of 4).
A news article from 23 October noted that 3,500 families had been evacuated from the Chiles, Panam, and Mayasquer communities.
Geologic Background. The Chiles-Cerro Negro volcanic complex includes both the Pleistocene Chiles and the Cerro Negro de Mayasquer stratovolcanoes astride the Colombia-Ecuador border. Cerro Negro has a caldera open to the west, with andesitic and dacitic lava flows of possible Holocene age (Hall 1992, pers. comm.) and solfataras on the shore of a small crater lake. An eruption reported in 1936 may have been from Reventador (Catalog of Active Volcanoes of the World). The higher, glacier-covered summit of Chiles, about 4 km ESE of Cerro Negro, last erupted about 160,000 years ago, but it has a caldera open to the north with hot springs and an active hydrothermal system on its eastern flank.