Geographers and dendrochronologists teamed up in a cross-disciplinary study to look at the correlation between tree rings and volcanic eruptions, reports the Swiss Federal Institute for Forest, Snow and Landscape Research WSL and the ETH Zurich. Their results gathered from Mount Etna's west flank which erupted in January, 1974, state evidence that tree rings may be able to predict eruptions.
Scientists know that tree rings can provide a lot of of environmental information. For instance, the ring width reflects the tree's growth conditions, which are a combination of the temperature, precipitation and nutrient conditions during a given growing season, explains ScienceDaily. But this new study, published in Scientific Reports, makes it clear that tree rings may provide even more information than previously thought. "The ring width may also be influenced by volcanic activity on Mount Etna and in other volcanic regions," states geographer Ruedi Seiler, a PhD student at WSL.
The significance of this discovery is particularly important because a volcano’s history may provide key information in how it will behave in the future - in other words, knowing when and in what conditions a volcano erupted previously may help scientists to understand and predict when it could erupt again, which is obviously critical to putting protective measures in place. "I see great potential in this observation: we may be able to use tree rings to reliably date minor flank eruptions," says Nicolas Houlié, a geophysicist at ETH Zurich.
Although real-time monitoring with GPS, seismometers and gas monitoring devices have provided the scientific community with details for eruptions in the last twenty years, and the dates of volcanic events prior to 2,000 years ago can be determined using the C14 method, information about volcanic eruptions occurring in that gap of time is lacking. Houlié thinks that tree rings may provide a link for those eruptions: "Tree ring data could help to close the information gap for the period stretching from 20 to 2,000 years ago."
Houlié first noticed this trend while looking at a satellite image of a three kilometer green line on the north-east flank of Mount Etna (known as the Normalized Difference Vegetation Index (NDVI) which shows that the volcano erupted along that exact line a year later. Although there were no changes to the trees' growth before the 1974 eruption, the researchers highlight that the trees grew less in the two summers following the eruption than in other years, explains ScienceDaily. This could be enough to go back in tree ring histories and note patterns that play out in the volcanoes’ eruption events.