Intrusion now 40 kilometers long

26.08.2014 - 15:32
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The dike intrusion north of Bardarbunga is now about 40 kilometers long, and the most intense seismic activity has been at the northern end of the intrusion. Its volume is believed to have increased by 50 million m³ over the last 24 hours. A 4,6 Magnitude earthquake was detected at noon today.

About 700 earthquakes have been detected since midnight; most of them in the northern part of the intrusion, which has now reached about 7 km. outside the margin of the Dyngjujokull outlet glacier. Models of the intrusion, based on GPS measurements and earthquake resolutions have indicated that about 0,35 km³ of magma have entered the intrusion from the beginning of the event, on August 16. Over the last 24 hours, the magma volume is believed to have increased about 0,5 km³ (50 million m³). 

At 01.26 GMT this morning, a 5,7 Magnitude earthquake was detected in the northern rim of the Bardarbunga caldera. This quake, and others detected there, are believed to be associated with pressure changes in the magma chamber beneath the caldera, as magma flows outwards. 

Scientists and technicians have been travelling around the northwestern part of Vatnajokull in recent days, improving the net of seismometers and GPS measurement equipment. 

According to the Icelandic Met Office, three scenarios are now considered likely: 

- That magma flow to the intrusion stops and the event does not lead to an eruption. 

- That the intrusion reaches the surface and an fissure eruption begins, most likely at the northern end of the dike, outside of the glacier. In that event, a lava eruption with moderate tephra/ashfall is expected. 

- That the intrusion reaches the surface partly or mostly subglacial. In that case, the eruption would lead to a glacial flood (jokulhlaup) in the Jokulsa a Fjollum glacial river and potentially an explosive eruption with extensive ashfall. 

Other scenarios, such as an eruption in the Bardarbunga caldera can not be excluded, according to the IMO, but are presently considered much less likely. 

This story, by the Icelandic National Broadcasting Service (RUV), was updated on August 26. 2014, at 15.30 GMT.

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