The quakes in Bárðarbunga are marked with green stars.
© IMO
The quakes in Bárðarbunga are marked with green stars.
A strong earthquake swarm hit the monster volcano Bárðarbunga late yesterday evening, Monday. Two separate 4+ earthquakes, including a 4.6 magnitude quake, as well as one measuring more than 3 on the Richter scale hit in short succession around midnight. The epicenters of all the quakes were in the eastern part of the caldera, at a significant depth.

According to the Seismic Monitoring System of the Icelandic Meteorological Office the first quake, a 2.8 magnitude quake was detected at 23:34 at a depth of 4.1 km (2.5 mi), followed by a second 2.7 magnitude quake 17 seconds later at a depth of 2.5 km (1.6 mi). Nine minutes past midnight a magnitude 4 quake was then detected at a depth of 1.1 km (0.7 mi). At the exact same moment a second, 4.6 magnitude quake was detected closer to the center of the caldera, at a depth of 7.1 km (4.4 mi). These were then followed by a third sharp 3.5 magnitude quake at a depth of 2.2 km (1.4 mi).

Geophysicists believe the activity in Bárðarbunga is caused by magma being thrust from the earth's mantle up into the magma chambers beneath the volcano's caldera. The volcano has been showing increasing levels of activity for the past year or so, following the 2014-15 Holuhraun eruption at the northern edge of the system.