Photo of the eruption at Mount Redoubt in Alaska in 2009. Credit: Game McGimsey, USGS
New research methods could lead to earlier predictions of volcanic eruptions.
Although there are signs that a volcano is likely to erupt in the near future – an increase in seismic activity, changes in gas release and sudden deformation of the ground, for example – the infamous prediction of such eruptions is difficult.
This is partly because no two volcanoes behave in exactly the same way and because few of the world’s 1500 or so active volcanoes have monitoring systems in place. Under the best conditions, scientists can accurately predict an eruption of a monitored volcano a few days before it happens. But what if we knew months or even years before?
Using satellite data, scientists at NASA‘s Jet Propulsion Laboratory in Southern California and the University of Alaska, Fairbanks, have developed a new method that brings us closer to reality. The research was recently Nature Geoscience is an annual scientific journal published by the Nature Publishing Group, covering all aspects of Earth Sciences, including theoretical research, modeling, and fieldwork. Other related work is also published in fields that include atmospheric sciences, geology, geophysics, climatology, oceanography, paleontology and space science. It was established in January 2008.
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“The new methodology is based on a subtle but significant increase in heat emissions over large parts of a volcano in the years before its eruption,” said lead author Társilo Girona, formerly of JPL and now at the University of Alaska, Fairbanks. “It allows us to see a volcano wake up again, often before any of the other signs appear.”
Scientists recently discovered that Mount Domuyo in Neuquen, Argentina, shown here is an active volcano. Credit: Adobe Stock / Guillermo Cisneros
The study team analyzed 16 ½ years of radiant heat data from the Moderate Resolution Imaging Spectroradiometers (MODIS) – instruments aboard NASA’s Terra and Aqua satellites – for different types of volcanoes that have erupted over the past two decades. Despite the differences between the volcanoes, the results were uniform: in the years leading up to an eruption, the radiant surface temperature rose over a large part of the volcano by about 1 degree. Celsius from its normal state. It decreased after each eruption.
“We are not talking here about hotspots, but rather about the warming of large parts of the volcanoes,” said co-author Paul Lundgren of JPL. “So it’s probably related to fundamental processes that take place in depth.”
The scientists especially believe that the increase in heat may result from the interaction between magma reservoirs and hydrothermal systems. Magma (molten rock beneath the earth) contains gases and other liquids. As it rises through a volcano, the gases spread to the surface and can give off heat. This degassing can also facilitate the inflow of groundwater and the elevation of the water table, as well as hydrothermal circulation, which can raise the soil temperature. According to scientists, other processes may also be underway, because although their understanding of volcanic behavior improves, it remains limited.
“Volcanoes are like a box of mixed chocolates: it may look like it, but there is a lot of variety between them, and sometimes even within the same,” Lundgren said. “In addition, only a few volcanoes are well monitored and some of the most dangerous volcanoes are the least explosive, which means you can not rely heavily on historical records.”
Combine data
The new method is significant in itself, but it can provide even more insight into volcanic behavior when combined with data from models and other satellites.
In a study published in Scientific reports Last summer, Lundgren used data from interferometric synthetic diaphragm (InSAR) data to analyze long-term deformation at the Domuyo volcano in Argentina. At the time, scientists were not sure if Domuyo was a dormant or extinct volcano, or if it was just a mountain. Lundgren’s research quickly clarified this. He unexpectedly detected a period of inflation, that is, when a part of a volcano expands while a new mass of magma moves upwards and pushes rock out of the way. It turns out that Domuyo is very much a volcano – and an active one.
Lundgren then compares this deformation time series to the thermal time series created by Társilo Girona for the Domuyo volcano. Lundgren’s aim: to determine whether the two processes – an increase in radiant surface temperature over large parts of the volcano and deformation – are connected.
“We found that the thermal time series closely mimicked the deformation time series, but with some time separation,” Lundgren said. “While it is unclear what process is likely to happen first, by indicating the correlation, we can connect the processes through physics-based interpretations rather than simply relying on what we can observe on the ground.”
In other words, the combination of the data sets provides clues as to what is happening deeper in the volcano and how the different processes influence and interact with each other – data that the accuracy of models used to predict eruptions.
‘Although the research does not answer all the questions, it does open the door to new remote sensing approaches – especially for distant volcanoes – that should give us some fundamental insights into competing hypotheses about how volcanoes behave in general dynamic behavior over some time scales. of a few. years to decades, ”Lundgren added.
Look ahead
In the future, scientists will test the thermal time series method on more volcanoes and refine its precision.
“One of the goals is to one day have a tool that can soon be used in real time to look at volcanic activity in volcanic areas,” Girona said. “Even for small eruptions, there is evidence of thermal turbulence before the onset of the eruption event, so the new method helps us get a little closer to the goal.”
The data help supplement existing tools used in monitored volcanoes. But it also significantly increases the number of volcanoes for which life-saving data can be made available.
‘Using the new thermal method that detects changes in the surface temperature around volcanoes and the InSAR surface distortion measurements help identify volcanic observatories around the word which volcanoes are most likely to erupt and which volcanoes need to be equipped for closer observation, Said Lundgren. “Using satellite data increases the scope of what can be monitored regularly.”
As for the once largely ignored Domuyo, the story is still evolving: it is one of several volcanoes recently prioritized by the Argentine government to be equipped with a monitoring system.
References:
“Large-scale thermal eruption of volcanoes years before the eruption” by Társilo Girona, Vincent Realmuto and Paul Lundgren, 11 March 2021, Natural Sciences.
DOI: 10.1038 / s41561-021-00705-4
“The Dynamics of Large Silica Systems from Satellite Observations: The Intriguing Case of Domuyo Volcano, Argentina” by Paul Lundgren, Társilo Girona, Mary Grace Bato, Vincent J. Realmuto, Sergey Samsonov, Carlos Cardona, Luis Franco, Eric Gurrola and Michael Aivazis, 15 July 2020, Scientific reports.
DOI: 10.1038 / s41598-020-67982-8