NASA satellites detect signs of volcanic activity years before an eruption.
While there are clear signs that a volcano could erupt in the near future – such as increased seismic activity, changes in gas emissions, and sudden ground deformations – it is extremely difficult to accurately predict when an eruption will occur.
This is because none of the volcanoes behave in exactly the same way, and also because few of the world’s 1,500 active volcanoes have their own monitoring systems. Under the best of circumstances, scientists can accurately predict an eruption of an observed volcano several days in advance. But what if we knew of the impending eruption months or even years in advance?
Using satellite data, scientists from NASA’s Jet Propulsion Laboratory in Southern California and the University of Alaska in Fairbanks have developed a new method that brings us closer to this reality. This research was recently published in Nature Geoscience.
The new methodology relies on the subtle but significant increase in heat emissions over large areas of the volcano in the years preceding its eruption. This allows us to see that the volcano has woken up again, often long before any other signs appear, said Tarsilo Girona, lead author of the study, who previously worked at the Jet Propulsion Laboratory and now at the University of Alaska in Fairbanks.
The research team analyzed 16.5 years of radiant heat data from Moderate Resolution Imaging Spectrometers (MODIS) instruments aboard NASA’s Terra and Aqua satellites of several types of volcanoes that have erupted during the past two decades. Despite the differences between the volcanoes, the results are consistent: In the years before the eruption, the radiating surface temperature over a large portion of the volcano rose by about 1 ° C above its normal level. The temperature decreased after each eruption.
We’re not talking about hot spots, we’re talking about warming large areas of volcanoes. It’s likely linked to in-depth fundamental processes, said Paul Lundgren of the Jet Propulsion Laboratory, co-author of the study.
In particular, scientists believe that the increase in heat may be due to interactions between magma reservoirs and hydrothermal systems. Magma (molten rock under the Earth’s surface) contains gases and other fluids. When it rises through a volcano, gases diffuse to the surface and can emit heat. Likewise, this discharge can facilitate the flow of groundwater and raise the water level as well as the hydrothermal circulation which can increase the soil temperature. But scientists say other processes may also be involved, because while their knowledge of volcanoes continues to improve, it remains limited.
Volcanoes are like a box of mixed chocolate: They may look the same, but inside there is a lot of variety between them, sometimes even within the same volcano. Moreover, only a few volcanoes are well monitored, and some of the more dangerous volcanoes are the least likely to erupt, which means you cannot rely solely on historical records, Lundgren added.
The new method is important in its own right, but it could provide deeper insight into volcanoes when combined with data from other models and satellites.
In a study published in Scientific Reports last summer, Lundgren used Synthetic Aperture Interferometry Radar (InSAR) data to analyze the long-range deformation of Argentina’s Domio volcano. At the time, scientists weren’t sure if Domoyo was an extinct or extinct volcano, or if it was just a mountain. Lundgren’s research quickly clarified this. Unexpectedly, scientists have discovered a period of inflation, a condition in which a portion of the volcano expands as the new magma mass moves up and pushes the rocks out of the way. It turns out Domuyo is pretty much a volcano – and it’s active at it.
Lundgren then compared this deformation time series with the thermal time series created by Társilo Girona for Domuyo volcano. Lundgren’s goal was to determine whether the two processes – warming of surface radiation over large areas of the volcano and deformation – are related to each other.
We found that the thermal time series closely followed the deformation time series, albeit with some time separation. Lundgren explained that even if it remains unclear which process is likely to occur first by showing correlation, we can relate processes through physics-based explanations, not relying solely on what we can observe beneath the Earth’s surface.
In other words, the mix of data sets provides clues about what is going on deep in the volcano and how different processes affect and interact, which can improve the accuracy of the models used to predict volcanic eruptions.