Greener plants can be used to predict when a volcano is about to erupt, potentially providing a warning long before more conventional methods of volcano monitoring.
An increase in carbon dioxide emissions is often one of the earliest signs of volcanic unrest, but it is difficult to detect against usual background levels of the gas and difficult to measure directly because so many volcanoes are in inaccessible and heavily vegetated areas.
To get around this problem, Robert Bogue, at McGill University in Canada, and colleagues decided to investigate whether plant health could be used as a proxy for volcanic activity.
By studying satellite images of Yellowstone National Park in the US, taken between 1984 and 2022, they were able to show that plants became greener in places where volcanic activity was building (due to the extra carbon dioxide that helps promote plant growth ), followed by browner when the volcanic activity peaked (due to sulfur dioxide and high temperatures killing the plants).
The findings, published in Geochemistry, Geophysics, Geosystemssuggest that using satellite imagery to monitor plant health could alert us to volcanic activity years in advance.
The technique is likely to work well on broad cone-shaped stratovolcanoes in forested areas such as Taal Volcano in the Philippines or Mount Etna in Italy.