The Arctic seabed is as explosive geologically as it is politically judging by the "fountains" of gas and molten lava that have been blasting out of underwater volcanoes near the North Pole.
"Explosive volatile discharge has clearly been a widespread, and ongoing, process," according to an international team that sent unmanned probes to the strange fiery world beneath the Arctic ice.
They returned with images and data showing that red-hot magma has been rising from deep inside the earth and blown the tops off dozens of submarine volcanoes, four kilometres below the ice. "Jets or fountains of material were probably blasted one, maybe even two, kilometres up into the water," says geophysicist Robert Sohn of the Woods Hole Oceanographic Institution, who led the expedition.
Chunks of broken sea floor rock, or "talus ejecta" and large-grain pyroclastic deposits cover an outer slope of the Oden volcano on the seabed floor near the North Pole.
He and his colleagues, who describe the underwater scene in the journal Nature today, estimate that exploding mixtures of lava and gas flew out of the volcanoes at speeds of more than 500 metres a second. When the material hit the frigid seawater, Sohn says it would have formed huge clouds that rained volcanic material down on the sea floor, creating the carpet of glassy shards and bits that can be seen for kilometres.
The team explored the volcanoes last summer as the Russians were planting a flag on the nearby sea floor triggering an international flap over ownership of the seabed.
Sohn said in an interview Wednesday that his crew of 30 researchers from the U.S., Europe and Japan chuckled over the "grandstanding" as the Russians rumbled by in their icebreakers. But they stayed focused on the intriguing spot on the Gakkel Ridge they had come to explore. The 1,800-kilometre-long ridge, which cuts across the Arctic from Greenland to Siberia, is in international waters. It is one of the planet's "spreading" ridges where molten rock rises up from inside the earth creating new crust.