The eruption of Cumbre vieja under the eye of the satellites of Copernicus

More than a week after the “Cumbre Vieja” volcano erupted on the Spanish island of La Palma, satellite imagery has been invaluable to the authorities” efforts to monitor and manage the crisis.

From measuring gas emissions to assessing damage, the Sentinel satellites of the European Copernicus network provided crucial data.

For example, the Copernicus emergency management service has thus made available daily maps to monitor the lava flow and to evaluate the number of buildings potentially affected by the advance of the molten rock. And according to the latest data, more than 1,000 homes and businesses were destroyed.

One of Copernicus’ satellites, Sentinel 5, is capable of detecting nitrogen dioxide (SO2) emitted into the atmosphere. Last Sunday, emissions reached Italy, as shown in the image (below) posted online by the environmental data analysis platform ADAM.

By combining satellite data and weather models, the Copernicus atmospheric monitoring service is able to predict the evolution of the SO2 plume that, in the coming days, will reach the Arctic Ocean through southern Spain, Italy and the Balkans before heading to the Atlantic Ocean.

Despite significant concentrations highlighted by the application, scientists agree that these concentrations are not dangerous to health or the environment. They remain at an altitude of 5,000 to 10,000 meters and will not have a particular influence on air quality and do not cause acid rain.

Satellites also give a more accurate picture of the eruption area. Remote sensing specialist Iban Ameztoy used data from Copernicus’ Sentinel 2 satellites to create animations that make it possible to “fly over” the area, thanks to one of the first cloudless images of a part of the large lava flow over the weekend.

On Sunday, September 26, the lava flow was also captured by NASA’s Earth observation satellite, Landsat 8.

Two days after Cumbre Vieja erupted, the most active volcano in Europe, Sicily’s Etna, also experienced another intense episode of activity, as evidenced by the lava and vast plume of smoke captured by the satellites of Copernicus.

Hard to get images

Satellite imagery is not an accurate and predictable science. To obtain good images, weather conditions are thus paramount. In addition, observation satellites pass over a particular location only every other day, which does not allow real-time observation.

Another important parameter is how the images are obtained and processed. Experts apply special filters to highlight aspects such as moisture or, in this case, to better see the lava flow.

Each satellite has its own specificity. Sentinel 2 satellites are the most powerful in terms of optical capabilities.

Margin of error

Sometimes these spectacular images can also give rise to misinterpretation. Last week, when the Atmospheric Monitoring Service showed sulfur dioxide emissions from the volcano, many rushed to “alert” about a possible SO2 “cloud” that would affect Europe. The scientists then explained that these emissions remain in the upper atmosphere and do not affect air quality. The gases from the La Palma volcano are certainly less harmful than the SO2 we produce by burning fossil fuels.

But questions remain, however, as the lava, after traveling six kilometers, reached the waters of the Atlantic Ocean on Thursday. This encounter between magma and seawater produces clouds where potentially toxic gases, such as chlorine, are present. Emanations that have so far caused no casualties.

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