Tuesday, 25 November 2014

Magnitude 5.4 Earthquake beneath the Vatnajökull Glacier in Iceland.

The Icelandic Met Office, which also monitors seismic activity, recorded a Magnitude 5.4 Earthquake at a depth of 4.1 KM beneath the Vatnajökull Glacier slightly after 9.00 am GMT on Monday 24 November 2014. This is roughly 4.1 m to the northeast of the Bárðarbunga Volcano, which lies beneath the Vatnajökull Glacier and which began an active cycle at the end of August 2014, with magma apparently rising beneath the volcano then migrating to the Holuhraun Lava field, to the north of the glacier. Magnitude 5.4 Earthquakes at shallow depths are potentially quite dangerous, but the remote location of this event makes it highly unlikely that there were any casualties or damage.

The approximate location of the 24 November 2014 Vatnajökull Glacier Earthquake. Google Maps.

 Seismic activity beneath volcanoes can be significant, as they are often caused by the arrival of fresh magma, which may indicate that a volcano is about to undergo an eruptive episode. Bárðarbunga last erupted in about 1862, and has undergone several periods of raised seismic activity since then, most recently in 1996 and 2010, so there is no reason to believe that this weeks events will automatically lead to an eruption from the volcano itself. Bárðarbunga began to undergo seismic activity (Earthquakes) on 19 August, and lava began to erupt from a fissure in the Holuhraun lava field, no the north of the Vatnajökull Glacier, late in the evening of Thursday 28 August, and has continued since then, with lava flows now covering over 37 square kilometres of land. 

Lava flows in the Holuhraun lava field. Arctic-Images/Corbis.

Iceland lies directly upon the Mid-Atlantic Ridge, a chain of (mostly) submerged volcanoes running the length of the Atlantic Ocean along which the ocean is splitting apart, with new material forming at the fringes of the North American and European Plates beneath the sea (or, in Iceland, above it). The Atlantic is spreading at an average rate of 25 mm per year, with new seafloor being produced along the rift volcanically, i.e. by basaltic magma erupting from below. The ridge itself takes the form of a chain of volcanic mountains running the length of the ocean, fed by the upwelling of magma beneath the diverging plates. In places this produces volcanic activity above the waves, in the Azores, on Iceland and on Jan Mayen Island.
The passage of the Mid-Atlantic Ridge beneath Iceland. NOAA National Geophysical Data Center.
See also...
The Icelandic Met Office recorded a Magnitude 5.4 Earthquake at a depth of 3.9 km beneath the Vatnajökull Glacier slightly before 7.10 am local time (which is...

Lava began to erupt from a fissure in the Holuhraun lava field, no the north of the Vatnajökull Glacier in central Iceland, late in the evening of Thursday 28 August, and has continued to do so for the next three days. The lava field lies to the northeast of  Bárðarbunga, a volcano...
The Icelandic Met Office recorded a Magnitude 5.0 Earthquake at a depth of 3 km beneath the Vatnajökull Glacier slightly before 8.15 am GMT on Thursday 28...
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