Alert level raised at Cerro Machín

Machín volcano, Colombia, 10 November 2008 (image copyright INGEOMINAS).

A seismic swarm on Saturday has provoked the Colombian state geological service INGEOMINAS to raise the alert level for Machín volcano in western central Colombia to Yellow (III), ‘ changes in the behaviour of the volcanic activity’.

According to a report in El Espectador, ’54 minor [earth] movements took place over the weekend at El Machín volcano. The largest of these was at 1.3 on the Richter scale. The seismic swarm took place from 5:00 p.m. on Saturday, and although small, is the largest to have occurred in 2009, after strong activity in 2008′. No bulletin on developments at Machín has yet been published on the Manizales Volcanological Observatory web site.

Any reactivation of Machín would pose a substantial threat to a populous area of Colombia, including the large city of Ibagué (approximate population 500,000).

UPDATE, 9 December 2009. A commenter at Erik Klemetti’s Eruptions blog observes that INGEOMINAS has had Machín at Yellow Alert for ages, and thinking back over my visits to the Observatorio Vulcanológico y Sismológico de Manizales site (where Machín bulletins are rather thin on the ground) it does seem that the yellow square has been a permanent fixture. I suspect the local press picked up on this activity because it’s the first for a while, and because the national government has prioritized a potential eruption of Machín as one of the principal natural disasters Colombia may have to deal with. In any case, the latest earthquake swarm is significant, and emphasizes the point that Machín needs careful monitoring.

News
54 sismos en volcán El Machín llevan a declarar alerta amarilla – El Espectador, 7 December 2009
En alerta Amarilla el volcán Machín – Semana, 7 December 2009
Authorities declare yellow alert for Machin volcano – Colombia Reports, 7 December 2009

Information
Global Volcanism Program: Machín – information about Machín volcano (1501-04=)
Observatorio Vulcanológico y Sismológico de Manizales – INGEOMINAS observatory responsible for monitoring Machín
Volcán Machín – information, maps and pictures