Activity at Tungurahua remains at moderately high levels, Reventador follows - Ecuador

Activity at Tungurahua remains at moderately high levels, Reventador follows - Ecuador

Following a violent eruption on July 14, 2013 internal and surface activity at Tungurahua remains at moderately high levels. Strong strombolian activity and near-continuous ash emissions are still present. During clear weather, eruption plume of about 1 km height can be observed drifting south-west.

According to IGEPN, low intensity noise can be heard in the vicinity of the volcano, there are numerous long-period earthquakes and an elevated output of SO2 is present (about 3000 tons per day). During the night of July 18, incandescence was observed at the top of the volcano and incandescent blocks were ejected descending 500 meters on the flanks.

The observed activity indicates the presence of a new magma body in the upper conduit which feeds the present activity. It is likely that this will continue in the short term, with a possibility of increase if new magma is being ejected at depth.

Most likely scenario is a continuation of moderate strombolian activity with moderate explosions ejecting varying amounts of ash and blocks that could affect the populations located in the vicinity of the volcano, in the direction of the prevailing winds. It seems less likely that the current eruption will evolve into a more violent activity.

However, as it happened in the past, the possibility of pyroclastic flows cannot be ruled out, and these could threaten areas on the lower slopes where farming activities are being conducted. 

Another significant hazard are mud flows (lahars) that can be caused by mixing rain water with loose ash and block deposits. Areas particular at risk include stream valleys near Banos, Penipe and the sectors of the Pampa and Vascún.

Meanwhile, effusive and explosive activity at the surface as well as seismicity have continued to increase at Reventador. A lava flow is traveling from the summit crater on the southern side towards the SE flank and there are numerous small explosions which create ash plumes of up to about 1 km height. 

IGEPN summarizes the evolution since July 12: 

- 12 July: so-called drumbeats seismic signal, typical for magma ascent, followed by signals of rockfalls - this is likely the start of the lava flow. 
- 13 July: an explosion and few long period (LP) tremors (typical for fluid movements) 
- 14 July: low activity 
- 15 July: more explosions and LP quakes as well as a strong pulse of tremor (continuous vibration) 
- 16 July: numerous LP quakes and volcanic tremor, few explosions 
- 17 July: starting at 10:30 (local time), a series of small and moderate explosions starts, accompanied by LP quakes. 
- 18 July: LP quakes, tremor and explosions. 

On July 18th, at approximately 18h30 (local time), there was an explosion that produced a column of gas and ash that reached about 1 km above the crater. The ashes scattered in the surrounding area.​

A list of Ecuador's volcano webcams is here.

Source: IG-EPN

Featured image: Area in the red box shows the path of the lava flow on Reventador's southern flank. Image courtesy P.Narváez Camp San Rafael - Coca Codo Sinclair

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