Plants predict where rumbling volcanoes will blow

WANT to know where a rumbling volcano is likely to split at the seams? Look for the tallest and greenest plants.

Vigorous plant growth on the flanks of a volcano like that at Rabaul, Papua New Guinea (above), can indicate where magma is most likely to spurt out. Satellite images reveal that shrubs and trees grow taller and greener along stripes where the volcano eventually ruptures.

Nicolas Houli from the University of California, Berkeley, and his colleagues studied satellite images of Mount Etna in Sicily and Mount Nyiragongo in the Democratic Republic of the Congo. When they compared before and after pictures of the volcanoes they found a significant increase in plant reflectivity and greenness along the eruption fissures. These changes were visible up to two years before the eruptions, the team says in a forthcoming issue of Earth and Planetary Science Letters.

Theories for why this pattern of growth occurs include better water supply in the cracks where the plants grow, and more carbon dioxide seeping out of the ground.

“I was happy to see this paper as this technique could apply to many volcanoes and be of great help,” says Agust Gudmundsson, a volcanologist at the University of Gttingen in Germany. Knowing which way lava is likely to flow would help in planning evacuations.