New research carried out by scientists at Oxford and Bristol Universities has shown that the volcanic islands of Santorini are expanding, with uplift in the centre of 14cm between January 2011 and April 2012. Published online in Nature Geoscience this expansion has been caused by the intrusion of 10-20 million cubic metres of magma underneath the volcano, potentially priming it for eruption in the future.
But don’t go canceling that holiday to Santorini just yet. An eruption is unlikely to be coming anytime soon – especially as seismic activity on the island has trailed off. The estimated volume of magma intruded is somewhere between 20 and 50% of the volume typically erupted in a small eruption on the island (the last one of these being in 1950) – a volume equivalent to 15 of that well known unit of measurement: olympic stadiums. It is a significant amount of material and goes a long way to confirming the hypothesis that the build up of magma beneath Santorini is likely to be an episodic process rather than a slow continual one.
The small eruptions generally build up the island, and the size of the eruption is typically proportional to the length of time between them. However, the volume of magma is still a long way off from the volume that would cause a more explosive destructive eruption like the one that destroyed the island in 1628BC (or so) and possibly the entire Minoan civilisation with it.
What I find cool, is how they work out this stuff. They use high precision GPS, accurate to a couple of mm, and record the gradual changes over months and years.
This is combined with a satellite technology called INSAR, which uses Radar to calculate the distance to the ground, and how this changes between successive passes of the satellite. This data is often used to determine the amount of movement in the earth’s crust during large earthquakes. Also seismic stations help to build up a big picture of activity on the island.
Journalist-y type report here.