GabyScientists have learned to tell when a volcano is gearing up to erupt by watching the surrounding trees. Before an eruption, those trees often green up—brighter leaves can signal a potentially imminent lava flow.
Until now, these subtle color shifts could only be spotted on the ground, but volcanologists have recently started monitoring them from space. That shift came from a collaboration between the National Aeronautics and Space Administration (NASA) and the Smithsonian Institution.
NASA said the new discovery could “change the game” for detecting the first signs of a volcanic eruption. The finding will help protect people from the devastating consequences of eruptions, including lava flows, falling rocks, landslides, and clouds of ash and toxic gases.
Florian Schwandner, a volcanologist and head of the Earth Sciences Division at NASA’s Ames Research Center in California, emphasized that the goal is to improve early warning systems for volcanic eruptions.
Satellites to the rescue
Signs of an imminent eruption visible from space include seismic activity, changes in the Earth’s surface height, and sulfur dioxide emissions. Scientists also monitor carbon dioxide (CO2) emissions associated with magma activity. However, satellites find it more challenging to detect CO2 than sulfur dioxide because CO2 is widespread in the Earth’s atmosphere.
“The release of a small amount of carbon dioxide, which may signal an eruption, will not be visible in satellite images,” said graduate student volcanologist Robert Bough.
Researchers are eager to detect CO2 emissions because they can be an early sign of an impending eruption. To do that, scientists developed a method that uses trees around volcanoes to monitor carbon dioxide, Live Science reported. CO2 that leaks from a volcano can fertilize nearby trees and plants, making their leaves greener and lusher.
Previously, measuring CO2 levels required scientists to travel to volcanoes. But now they don’t have to visit these remote and often dangerous places. Researchers can use satellites to capture the brightness of tree foliage – an indicator of volcanic gas concentration.
A recent study published in the journal Remote Sensing of Environment found a strong correlation between carbon dioxide levels and the intensity of tree color around Mount Etna in Italy. Using images taken by Earth-observation satellites from 2011 to 2018, the authors observed 16 distinct spikes in CO2 levels and particularly vibrant greenery that coincided with magma migrations at the volcano.
To expand the potential of the new method, researchers have launched the Airborne Validation Unified Experiment: Land to Ocean (AVUELO), during which satellite images of trees around volcanoes will be compared with ground observations. This will provide greater data accuracy and help scientists better calibrate space instruments.
Unfortunately, measuring the intensity of greenery from space is not a universal method for detecting eruptions. Not all volcanoes have nearby trees, or there may not be enough trees for observation from satellites. Trees damaged by fires, disease, or extreme weather may respond differently to changes in carbon dioxide levels.
