Trees near a volcano appear greener when it nears eruption: NASA study

Scientists have found that the health of tress around volcanoes can indicate if it is becoming more active and might erupt.

NASA scientists, in partnership with the Smithsonian Institution’s AVUELO (Airborne Validation Unified Experiment: Land to Ocean), said they can detect early signs of volcanic eruptions by observing the changing colours of leaves from trees.

Previously, the subtle colour changes in tress could only be observed from the ground but latest research has found a way to monitor them from space. In a statement released by the space agency, they said these changes are visible in images from NASA satellites such as Landsat 8, along with airborne instruments flown as part of AVUELO.

"Volcano early warning systems exist," Florian Schwandner, a volcanologist and chief of the Earth Science Division at NASA's Ames Research Center in California, said in the statement. "The aim here is to make them better and make them earlier."

Seismic activity, changes in ground height, and sulfur dioxide emissions which are visible from space are the current indicators of a volcanic eruption. Carbon dioxide emissions are also observed by scientists, however there are some restrictions.

When magma rises under the Earth's crust, gases - sulpher dioxide, carbon dioxide - are released. Research has showed tropical plants located near volcanoes absorb the carbon dioxide, making them look greener and healthier.

Tracing the emission of sulphur dioxide in the atmosphere is relatively easier compared to carbon dioxide, because the latter blends with other gases in the atmosphere.

"A volcano emitting the modest amounts of carbon dioxide that might presage an eruption isn't going to show up in satellite imagery," Robert Bogue, a doctoral student in volcanology at McGill University, Canada, said in the statement.

Researchers are interested in detecting the emission of carbon dioxide - which occurs even before sulphur dioxide emission - as it is the very first sign of a imminent eruption.

There are 1,350 active volcanoes worldwide, mostly located in remote areas, making it difficult for scientists to measure the carbon levels in their vicinity. As part of the research, scientists had to trek through rugged and sometimes dangerous mountain terrains.

Volcanologists have teamed up with botanists and climate scientists to study trees to monitor volcanic activity.

"The whole idea is to find something that we could measure instead of carbon dioxide directly," Bogue said.

The statement said using satellites to monitor trees around volcanoes would give scientists earlier insights into more volcanoes and offer earlier warnings of future eruptions.