Grimsvotn last erupted in May 2011 which canceled over 900 flights when it created a major ash cloud seven miles (12km) into the air. The eruption was the largest in Iceland for 50 years.
The Icelandic Meteorological Office has changed the eruption alert from “yellow” to “orange” due to heightened seismic activity and glacial melting surrounding the volcano.
Despite several small earthquakes recently reported nearby, officials say they have not detected any tremors which have caused an increase in underground magma.
Authorities revealed on Monday one of the nearby quakes was a 3.6 magnitude tremor.
On Monday, the Icelandic Meteorological Office (IMO) raised its alert level to “orange” due to “high seismic activity”.
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Grimsvotn volcano is located in the Icelandic highland, underneath Vatnajokull – the country’s largest glacier.
According to meteorologists, the ice cap on Grimsvotn’s subglacial lake had subsided by about 252ft (77 metres), and most of the water is now believed to have disappeared.
“Examples are that volcanic eruptions can occur in Grimsvotn after water is drained from there,” meteorologists said.
“It is believed that volcanic eruptions can occur after sudden pressure release due to reduced water level in the lake.
“The last time something similar happened was in 2004, 1934 and 1922.”