The new fissure at Fimmvörðuháls

The sudden appearance of a new eruptive fissure at Fimmvörðuháls yesterday took onlookers by surprise, according to news reports from Iceland: around 50 people had to be evacuated by helicopter, and the area around the eruption is now closed to tourists. A report in Morgunblaðið puts the length of the new fissure at 300 metres, and its location as 200 metres north of the initial location of the eruption, while RÚV reports the length as 300-400 metres. The new fissure trends north-south, roughly at right angles to the east-west alignment of the first fissure. A video of the activity beginning at the new fissure can be found here (H/T Jón Frímann). The picture above is from the Fimmvörðuháls webcam, and was taken at 08:00 GMT this morning.

The Icelandic Met Office have published an article looking at what the patterns of seismicity at Eyjafjallajökull reveal about the path of the magma over the period 13-24 March: ‘The magma path revealed’. It seems that the main feeder conduit for the eruption is situated beneath the eastern part of the Eyjafjallajökull ice-cap and rises nearly vertically to around 2-3 km depth, and then changes direction to run horizontally eastwards for about 4.5 km to the point outside the ice margin where the eruption began on 21 March 2010. The article does not speculate about the possible reasons for the horizontal diversion: local faulting, or the hardness/composition of the rock beneath the ice-cap perhaps?

The most urgent question now is whether further fissures will open, and where. The current seat of the eruption is located between two icecaps; the emergence of a new fissure beneath the ice would renew the threat of a jökulhlaup or glacial meltwater flood.

For all our Eyjafjallajökull coverage: Eyjafjöll « The Volcanism Blog.

News
Ný sprunga opnaðist – myndir – RÚV, 31 March 2010
Iceland: new craters open up. ‘We saw the Earth open up’ – Iceland Review Online, 1 April 2010
Nýr gígur á hálsinum – Morgunblaðið, 1 April 2010

Information
Global Volcanism Program: Eyjafjöll – summary information for Eyjafjallajökull, which the GVP calls Eyjafjöll (1702-02=)