Professor of geophysics Magnús Tumi Guðmundsson told ruv.is this morning that as long as the Bárðarbunga caldera is not sinking faster than it has until now and the eruption in Holuhraun remains stable, the probability of a sub-glacial eruption will decrease.
However, if the caldera starts dropping faster, or the eruption in Holuhraun subsides, then the magma will likely find another way to the surface, he reasoned.
Volcanologist Ármann Höskuldsson told eyjan.is yesterday that he believes the current activity will lead to a sub-glacial eruption because there is much more magma underground than is currently being emitted at Holuhraun.
The caldera subsidence also indicates a sub-glacial eruption, although it is impossible to predict when it would start, he added.
According to Magnús Tumi, it is unusual that an eruption remains stable for such a long time. The Holuhraun eruption has now lasted three weeks and one has to go all the way back to the 1963-1967 eruption which created Surtsey island to find a comparable eruption.
The new lava in Holuhraun now covers 37 square km (16 square miles) and would cover most of Iceland’s capital, as seen on this map.