SOUTHAMPTON (CMC) — Scientists from the University of Southampton have uncovered evidence of a previously unknown large volcanic eruption in the Caribbean Sea.

The findings, published in the journal Geology says by studying ash layers, known as tephras, in marine sediments the scientists identified an eruption that took place on Guadeloupe 2.4 million years ago.

The research indicates this eruption is the largest documented volcanic event in the region since that time.

Lead author, Professor Martin Palmer of the University of Southampton said: “Volcanic eruptions are relatively common in this area of the world, but while they are very disruptive for the local community, as seen on Montserrat over the past 20 years, they do not generally have a major impact on neighbouring islands.

He said while a large eruption of the scale that has been identified would represent an important hazard to human populations in the wider region if it occurred today “it is very important to note that our research suggests that such events are rare in the Lesser Antilles [as] there is no indication that another large eruption is imminent.”

The research team analysed a sediment core recovered by the Integrated Ocean Drilling Program (IODP) Expedition at a site 30km southwest of Montserrat and 75km west of Guadeloupe in the northeastern Caribbean Sea. This is close to several volcanically active islands in the Lesser Antilles. The core contained an unusually thick (18 cm) tephra that was deposited 2.4 million years ago.

By analysing the isotopes, trace elements and grain morphology of the tephra, together with volcanological models, the researchers were able to identify the origin and magnitude of the large Volcanic Explosivity Index (VEI) 6 eruption.

In comparison, the largest Montserrat eruptions since 1995 had a VEI of 3-4.

“Reconstructing the magnitude of past volcanic eruptions is important to inform predictions about future eruptions and hazards. This is difficult to accomplish from records on land – old eruptions are often eroded away, buried beneath later eruptions, or obscured by vegetation and soil,“ Palmer said.