The Vatnajökull ice cap in Iceland lost about a tenth of its mass during the twentieth century. As a result, the crust around its edges has risen and this, according to new research, has led to the rapid build-up of significant volumes of magma.
The finding suggests that melting glaciers can increase local volcanic activity over time periods that are relevant to humans. Carolina Pagli of the University of Leeds, UK, and Freysteinn Sigmundsson of the University of Iceland in Reykjavík calculated the rate of change of pressure decrease in the mantle beneath the 8,000-square-kilometre Vatnajökull ice cap. They then built a model that estimated the extra magma produced in the area to be 1.4 cubic kilometres per century. Taking the last major eruption below the ice cap as a metric, that would be equivalent to an eruption every 30 years if all the magma were ejected.