Scientists see volcanic eruption 'trigger'

SOUTHAMPTON, England, Oct. 12 (UPI) -- British scientists say they have identified a repeating underground trigger for the largest explosive volcanic eruptions on Earth.

Researchers from the University of Southampton have been studying the Las Canadas volcanic caldera on Tenerife in the Canary Islands, which has generated at least eight major eruptions during the last 700,000 years.

These catastrophic events have created eruption columns more than 15 miles high and thrown gas and ash over 80 miles away from the volcano, they said.

In an analysis of igneous rocks discovered in pyroclastic deposits of major eruptions, the scientists found pre-eruptive mixing within the magma chamber of older cooler magma with younger hotter magma appears to be the repeating trigger in large-scale eruptions, a Southampton release said Friday.

The analysis showed signs of major mixing events in the magma chamber immediately before eruption, they said.

"Stirring young hot magma into older, cooler magma appears to be a common event before these explosive eruptions," researcher Rex Taylor said.

The Las Canadas volcano is considered worthy of particular study in light of its history of large, destructive eruptions and its proximity to populated areas, the researchers said.