Greener trees can provide early warning of volcanic awakening

Greener plants can be used to foretell 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 hard to detect against ordinary background levels of the gas and difficult to measure directly because so many volcanoes are in inaccessible and heavily vegetated areas.

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Studying satellite images from Yellowstone national park in the US, taken between 1984 and 2022, they were able to show that plants became greener in the locations where volcanic activity was building (due to the extra carbon dioxide helping to boost plant growth), followed by browner when the volcanic activity peaked (due to sulphur dioxide and high temperatures killing the plants).

The findings, published in Geochemistry, Geophysics, Geosystems, suggest that using satellite images to monitor plant health could alert us to volcanic activity years in advance.

The technique is likely to work well on broad conical shaped stratovolcanoes in forested areas such as Taal volcano in the Philippines or Mount Etna in Italy.