Scientists have identified a crystal in volcanic rocks that could help estimate the size of future eruptions.
Volcanologists from the University of Geneva, in partnership with the University of Heidelberg, have devised a new approach based on a small crystal called zircon in volcanic rocks. This crystal contains uranium and thorium; radioactive elements whose crystallization can be dated.
Additionally, zircon only crystallizes in a specific temperature range that allows scientists to calculate the cooling rate of magma beneath the volcano. The greater the volume of magma, the longer it takes to cool it. Using thermal modeling, volcanologists can use the estimated magma cooling rate to determine the volume of magma beneath a dormant volcano. This volume of magma is not directly observable because it is located at a depth of between 6 and 10 kilometers.
“Knowing the size of a volcanic reservoir is important to identify volcanoes most likely to produce a large magnitude eruption in the future. Our method is a new way to assess candidates for such flares,” researcher Gregor Weber said Thursday.
This method – published in the scientific journal Nature Communication – was used on the dormant Mexican volcano of Nevado de Toluca, located in a densely populated area near Mexico City. Calculations have determined that the maximum size of a future eruption will be 350 km3, or about four times the volume of Lake Geneva.
According to the University of Geneva, the most devastating volcanic eruptions in the past 100 years have been from volcanoes that rarely erupt. These dormant volcanoes – which often have large populations nearby – have often gone under the radar of scientists. About 800 million people live around volcanoes worldwide.