Tunguarahua volcano (Ecuador): increased earthquakes could announce new eruption

Source: Volcano Discovery - 1/27/13, By T

A new phase of activity could be in the making. In its latest special bulletin, IG reports an increase of earthquakes, steaming and some minor ash emissions that have taken place during the past days.

In the past 2 weeks the Tungurahua volcano has been in maintained a low level of surface activity, limited to degassing from the fumaroles in the crater.

From January 24, a weak steam and gas column has been observed, reaching a height less than 1 km above the summit and drifting mainly S and SE. At 17h14 (local time), small ash emissions occurred producing a plume of 500 m and drifting SE. On the morning of January 25, fine black ash fall was reported from the Palictahua sector southwest of the volcano. During the day, a small steam and gas column rose less than 1 km above the volcano.

Additionally, two volcanic-tectonic earthquakes produced by rock fracturing rocks within the volcano were recorded and felt by people on the night of 24 January. The largest struck at 22h15 (local time) and had a magnitude of 3.2. Its hypocenter was located beneath the upper northwestern flank. Since then, 10 more but smaller earthquakes have been recorded so far.

The remaining parameters monitored by the Geophysical Institute have not shown significant variations. However, the increased seismicity associated with the surface activity indicate a potential change in the volcano's behavior, and an increase in activity in the coming days or hours is possible. Based on past episodes of activity, such a change into a new eruptive phase could occur both progressively and suddenly.