A surveillance flight over the Bardarbunga volcano this morning revealed continuing subsidence of the 850 metre thick glacial ice which covers the caldera beneath. Strong seismic activity is still detected around the caldera; the last one, a magnitude 5.0 earthquake occurred at 14.47 GMT.
Following a surveillance flight last Friday over the Bardarbunga caldera, when measurements revealed up to 15 meter subsididence in the center of the caldera, another flight was organized this morning.
The results show that the downward movement continues; since Friday the subsidence has increased by 2.5 - 3.0 metres, or 80-90 centimeters per day. "The events in Bardarbunga can only be described as a slow caldera collapse," says statement on the University of Iceland´s Institute of Earth Sciences´ website. The subsidence is the largest one measured in an Icelandic volcano.
These events are belived to occur in relation to the magma flow out of a chamber, thought to be situated beneath the caldera in Bardarbunga, as magma has been flowing to the north, feeding the effusive eruption in Holuhraun which started last week.
According to a status report issued Saturday, by the Icelandic Civil Protection Agency´s Scientific Advisory Board, the initial measurements from Friday showed dramatic changes on the surface of the glacier above the caldera, corresponding to a volume change of 0.25 cubic kilometres, or 250 million cubic meters.