The same goes for submerged calderas in the middle of the ocean, of which there are some examples near Japan.įor a time, scientists thought that Deception might be an unusual example of subduction happening in the ocean. Instead of taking place near the points between tectonic plates, these are holes in the ocean floor where there is a direct line to the Earth’s mantle. Most volcanoes at sea are like Hawaii and the Azores, which we describe as hot spots. The ones that scientists have observed happen on land. A classic example is the Cascade range in the north-western US, whose most famous volcano is Mt St Helens. Many volcanoes are caused by subduction, which is where two of the Earth’s tectonic plates crash against one another, sending one plate down and pushing the other upwards. Yet from a volcanic point of view, Deception is a great puzzle. Nowadays there are hazard maps to make visitors aware of the higher-risk spots on the island. We understand these subglacial eruptions much better now than we did in the 1960s. Ironically, the absence of larger glaciers is what made the island the most hospitable location in Antarctica. The scientists were not expecting it to produce much more than steam.

The reason why this melting was unexpected was because in scientific terms the glacier was “deceptively thin”. This was the main cause of the destruction of the UK and Chilean stations. This meant that it turned the glacier into meltwater as well as steam, creating a large overflow of mud to the surface. Scientists would normally expect that if this were hit by lava from below, it would evaporate benignly into steam.īut the lava moving upwards at Deception has several qualities that made things happen differently: it moves slowly and it has high water content. The island is situated in a place where there is a glacier on the ocean floor about 100m thick. The volcanic events at Deception fall into a rare category called subglacial eruptions.

Mt erebus green lava