While Iceland fears experiencing a powerful volcanic eruption, could France experience a similar situation? We asked the question to Patrick Allard, CNRS research director emeritus, volcanologist at the Paris Institute of Globe Physics (IPGP).
Iceland prepares for imminent volcano eruption Fagradalsfjall, in the southwest of the country, near the capital, Reykjavik. Areas of cracks appeared near the town of Grindavik, whose 4,000 residents were evacuated as a precaution. Unlike Iceland, “France is not at all in a dorsal zone of tectonic plate separation”estimates Patrick Allard, CNRS research director emeritus, volcanologist at the Paris Institute of Globe Physics (IPGP).
However, “the risks of eruption are less taken into consideration” as in Iceland or Italy, notably in the French West Indies where two volcanoes are active.
franceinfo: Can we know in France what Iceland is about to experience?
Patrick Allard: A priori, yes, it is possible. But it is not the same tectonic context. Iceland is located on the famous mid-ocean ridge and a volcanic chain that is 15,000 kilometers long, and approximately 1,500 meters high from the ocean floor, from which the tectonic plates that formed the Atlantic Ocean, the plates of North America and Eurasia. France is not at all in a dorsal zone of plate separation, but it has been affected in the past by zones of fracturing of the earth’s crust, such as the Rhône gap or the Rhine gap. Volcanoes were formed there, particularly in the Massif Central, where there was a volcano larger than Etna in Sicily: the Plomb du Cantal. It is now completely eroded.
Is the situation in the Massif Central comparable to what is happening in Iceland?
The most recent volcanism which would somewhat resemble that of Iceland is the Puys chain in Auvergne, where the last activity dates back 6,400 years. On a human scale, it seems far away, but on a geological scale, it is very recent! Where there are still active magma reservoirs, it is especially under the Dore mountains (Puy de Dome). We see that in the past of this region, there can be phases of activity and phases of pause of several thousand years. Volcanism in the Massif Central is in a phase of dormancy or even extinction for the Puys chain, but could resume in a few tens of thousands of years.
Are there risks of an eruption in mainland France?
No, not in mainland France. But very close to us, in Germany, there is a very active volcano which is on the Rhine divide: the Laacher see. It has had large eruptions in the past and is still fueled by a source of heat and gas. There are CO2 bubbles rising to the surface in a large crater lake.
“The Laacher see volcano could erupt again and one day pose problems for the whole of Europe.”
Patrick Allard, volcanologistat franceinfo
Volcanoes are like elephants, they tend to sleep and erupt from time to time. A volcano can sleep for 700 years like Pinatubo in the Philippines, and then wake up in 1991 to have a cataclysmic eruption.
We also have volcanoes that we know well, particularly in Overseas…
Yes, we have one of the most active volcanoes in the world: the Piton de la Fournaise, in Reunion, which has erupted two or three times a year on average in recent decades. This then generates large lava flows with not very explosive eruptions. It has quite recurring behavior so it is very predictable. All its eruptions for 15 years have been planned in advance. On the other hand, this is not the case for volcanoes in the Antilles, such as Mount Pelée in Martinique and Soufrière in Guadeloupe. Both are active, but currently dormant. They have more viscous, gas-rich magma. They make large explosions or “fiery clouds”, these kinds of incandescent clouds which can hurtle down the slopes at more than 200 km/h and burn everything in their path. The difficulty is to plan the evacuation of populations in time.
Are we prepared enough in the event of an eruption?
We have Orsec crisis management plans which are still under discussion between us, volcanologists, and the Ministries of the Interior and Ecological Transition. But in France, the risks are less taken into consideration than in Italy, which is understandable, because the Italians have large volcanoes at home. In France, they seem quite distant. There are regular meetings, particularly with the prefects, to improve evacuation plans in the event of an alert.
Our societies and our authorities in general are still reluctant to anticipate risks.
Patrick Allard, volcanologistat franceinfo
For floods, we are quite well organized, the authorities know how to do it. For volcanic eruptions, the authorities are perfectly organized in Reunion. But in the West Indies, it is more complicated, the volcanoes of Mount Pelée and Soufrière having not erupted for a long time, there are not the means or the attention that is needed.