Costa Rica's Volcano Turrialba largest eruption since 1866

The crater area of Volcano Turrialba as it looked yesterday. 

Credit: FotosAereasCR.com

During the night of 29th October 2014, a phreatic or ultravulcanian eruption occurred on Costa Rica's Turrialba Volcano lasting about 25 minutes.

The ash plume was blown in a west-southwesterly direction and ash fell in local villages and urban areas.

According to the seismogram, the eruption occurred between 23:10-23:35 (local time). Prior to the eruption, seismic unrest was detected and an increase in degassing activity was noted.

On the 28th and 29th October a measurement of a flow of 2000 tons of SO2 was noted compared to an average of 1300 tons per day in September.

Tony Lachner the manager of Volcan Turrialba Lodge, had observed the gas plume to be darker than usual.

Volcano Turrialba in it's largest eruption since 1866. 

Credit: Alejandro Calderon Aguilar.

Observations of the crater showed that the crater area was covered in ash, and OVSICORI-UNA reported that juvenile material was ejected during the eruptions.

The eruptions continued up to yesterday.

Yesterday saw the biggest eruption which had occurred on Turrialba Volcano since 1866.

The ash plume reached the height of 5.8km causing ash to fall as faraway as the capital San Jose, which is about 35km away.

Turrialba was raised to yellow alert status and a few evacuations have took place near the volcano.

Turrialba began erupting back in 2010 after a century and a half of dormancy although the eruptions since then up to yesterday were relatively small.