Machin volcano (Colombia): magnitude 4.6 earthquake on 7 Oct triggers seismic swarm

Source: VolcanoDiscovery.com - By T, 10/9/12

On 7 October at 21:32 and 21:35 (local time) 2 volcano-tectonic quakes with local magnitude 4.6 and 3.9 occurred beneath Cerro Machin at 12 km depth to the southeast of the main dome.

These earthquakes were felt by residents near the volcano, in the municipalities of Cajamarca and Ibague (Tolima), and in some municipalities in the departments of Risaralda, Quindio and Caldas.
These two events triggered in an increase in seismic activity which continued for a day, but seems to have calmed down for now.

As earthquake-report mentioned, Machin has not had any historic eruptions, but there are records of large explosive events in the past. The volcano awakened from a long period of dormancy in the 1990s with numerous earthquake swarms similar to the current ones, but so far has not produced an eruption.

The past several years have been relatively quiet ones at the volcano, but in the past few months, seismicity has again increased. Most of this activity is in the same region 12-15 km below the volcano and could indicate magma intruding there. It will be interesting to follow this volcano's activity in the coming months or years.