After the economic and airline disruption caused by the now infamous Eyjafjallajökull eruption in 2010, it's not surprising that the stirring of another Iceland volcano has gained great attention. This time it’s Bardarbunga, a volcano in central Iceland. Numerous earthquakes at 5 to 10 kilometers near the volcano have caused wide speculation about the potential of eruption. Associate Professor Josef Dufek is a volcanologist in the School of Earth and Atmospheric Sciences.
While it is still far from certain that this volcano will erupt, it is clear that magma is moving in the subsurface. The modest ground shaking observed at the surface is likely being generated by a dike event, where magma ascends along a fracture plane. Magma routinely stalls from such intrusions without reaching the surface. If the magma does reach the surface, it will still need to fragment and loft volcanic ash into the atmosphere before posing an aviation hazard similar to the events of 2010. The hazard for aircraft in such events is caused by abrasive volcanic ash, composed primarily of very small shards of quenched volcanic glass.
If eruption were imminent, the first indication would likely be shallowing of the magmatically driven earthquake sources as a dike propagates toward the surface. Thus far, this sort of seismic activity has not occurred. The current seismicity at depth is located beneath the considerable Vatnajökull ice-sheet, and any erupted magma would first interact with ice causing meltwater and potentially a large flooding event called a jökulhaup. In fact, one of the more probable indicators of an eruption would be greatly enhanced flow of water from glacial fed streams. The ice sheet thickness is significant, potentially as thick as 600 meters in the region above the magma, and this ice would need to be breached before any ash could access the atmosphere. This would take some time and would require a sustained eruption.
In the meantime, the Iceland Meteorological Office, which coordinates much of the observations of the volcano, has raised the aviation hazard to orange (next to highest level) to prepare for the potential of eruptive activity.
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