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Eruption of Fagradalsfjall in Iceland: CIEST2 initiative activated

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On 19 March, Iceland’s Fagradalsfjall volcano burst into life after remaining dormant for eight centuries. Using stereo imagery from the Pleiades satellites, Icelandic and French scientists were able to quickly determine daily lava and magma flow.

Iceland’s Fagradalsfjall volcano has been erupting for the last two weeks. It all began on 24 February, when two magnitude 5 earthquakes were recorded on the Reykjanes peninsula some 40 kilometres from the capital Reykjavik.

Since the eruption started, Icelandic scientists at the Institute of Earth Sciences, University of Iceland and the National Land Survey of Iceland have the volcano under close watch. Increased seismic activity and ground displacements measured by radar interferometry showed that magma was rising towards the surface. Icelandic scientists reached out to their French colleagues to request Pleiades satellite imagery.

ForM@Ter data hub activates CIEST2 initiative

On Saturday 20 March, the alert was raised and the CIEST2 natural disaster initiative at the ForM@Ter data hub was activated by Virginie Pinel, an expert in physical volcanology and remote sensing at the ISTerre Earth sciences institute. The Pleiades satellites were tasked the same day to acquire stereo imagery through the International Charter Space and Major Disasters.

The Pleiades rapid tasking request was executed through the Data Terra research infrastructure’s DINAMIS unit. A pair of Pleiades stereo images showing part of the volcano was acquired on Monday 22 March.

Interpretation of Pleiades stereo imagery acquired on Monday 22 March at 13:20. Pleiades©CNES, 2021 – Distribution Airbus DS.

Icelandic scientists worked with their French counterparts to interpret the imagery and generate a digital surface model (DSM) of the eruption area in less than 24 hours. Comparing the DSM with a two-metre-resolution archive model, they were able to calculate the thickness of lava from the eruption. Alongside this effort, French teams at ISTerre, LEGOS and ForM@Ter analysed results. On Tuesday 23 March, a fresh pair of images was acquired to compare the volume of lava and magma flow over 24 hours.

Second flow thickness map obtained on Tuesday 23 March after generating DSM from Pleiades imagery acquired on 23 March at 13:15, co-registered and compared with the Icelandic reference DSM.

First thickness of the lava flow obtained on Monday 22 March at midnight after generating the digital surface model (DSM) from Pleiades imagery, co-registered and compared with the Icelandic reference DSM. A volume of 1.33 million m3 gives a mean effusion rate of 5.8 m3/s since the start of the eruption. Second flow thickness map obtained on Tuesday 23 March after generating DSM from Pleiades imagery acquired on 23 March at 13:15, co-registered and compared with the Icelandic reference DSM.

Comparison of DSMs generated from Pleiades imagery acquired on Tuesday 23 and Monday 22 March. The difference in flow measured in 24 hrs is 0.48 million m3, corresponding to an effusion rate of 5.68 m3/s. Results obtained by Joaquin Belart (University of Iceland, National Land Survey of Iceland).

Qualifying the volcano plume with satellite imagery

The eruption in Iceland produced a plume of gas escaping from the eruptive fissure.

The Pleiades imagery acquired on 23 March 2021 highlights this volcano plume. Research scientists from the French geological survey BRGM involved in the CIEST² initiative used this satellite imagery to map the elevation and velocity of the plume.

This information is vital to predict volcanic ash and gas transport and dispersion in the atmosphere. The vPEM method (Volcanic Plume Elevation Model) is based on the small difference between PAN and XS acquisitions on the same Pleiades pass.

The eruption isn’t over yet and new eruptive vents could form in the days ahead. With the next acquisitions from Pleiades, scientists will be able to see how the magma flow is evolving.

The stereo imagery is available from the DINAMIS catalogue.

➡️ Learn more on the ForM@Ter data hub’s website


  • Information and CNES contact: Catherine Proy, ForM@Ter data hub project leader
  • Science contact: Virginie Pinel, ISTerre Earth sciences institute