The subsidence of the caldera in Bárðarbunga continues to cause uncertainty about the future development of the eruption. An event of this magnitude has not occurred since 1875 when Lake Öskjuvatn was formed in an eruption which caused major difficulties in Iceland and contributed to the mass exodus of Icelanders to North America.
Such a subsidence is not unusual globally. For example, the crater in Piton de la Fournaise á eyjunni Reunion in the Indian Ocean was lowered by 340 meters (1,000 feet) in 10 days in 2007 when a big eruption occurred. The Fernandina crater in Galapagos also subsided 300 meters (950 feet) in 1968 in similar circumstances.
Scientists Magnús Tumi Guðmundsson and Páll Einarsson speculate about this on the Institute of Earth Sciences website, mbl.is reports. They say that obviously there is a connection between the subsistence in Bárðarbunga and the eruption in Holuhraun. One of the possible scenarios is a major ash producing eruption in Bárðarbunga.