The researchers were able to pinpoint the exact timing of the massive eruption thanks to a layer of fossilized rock which showed mass extinction of different life forms -- clearly linking the volcanic blasts to a major environmental catastrophe.

"The abrupt extinction of marine life we can clearly see in the fossil record firmly links giant volcanic eruptions with global environmental catastrophe," said Paul Wignall, a professor and palaeontologist at the University of Leeds, who was the lead author of the research paper in the May 29 edition of Science.

The eruption in southwest China unleashed about a half million cubic kilometers of lava, covering an area five times the size of Wales, according to the research by scientists at the British university.

The mass extinction of ocean life came about because of the collision of fast flowing lava with shallow sea water, which caused a violent explosion at the start of the eruptions and threw huge quantities of sulphur dioxide into the stratosphere.

"When fast flowing, low viscosity magma meets shallow sea ... there's spectacular explosion producing gigantic clouds of steam," Wignall said.