In Martinique, the tremors of Mount Pelée under close surveillance

In Martinique, the tremors of Mount Pelée under close surveillance

Violet Field inPlanetDec 27, 2020 4 min read4 views

Some 50 earthquakes occurred in the volcano in September, and 78 in November, against less than 10 earthquakes per month until 2019

Mount Pelée, the Martinican volcano, was calm until its yellow vigilance of the Orsec plan on December 4. - KENZO TRIBOUILLARD / AFP

At the foot of Mount Pelée, in Martinique, residents have their eyes riveted on this still active volcano, which recently gave signs of reactivation to the point of putting scientists on alert since early December.

In Martinique, everyone remembers the damage caused by the volcano at the start of the 20th century: its eruption in 1902 left some 30,000 dead and wiped the city of St-Pierre, the little Paris of the Antilles, off the map. The neighboring commune, the Prêcheur, had been covered with ashes. If other eruptions marked the north of the island until the mid-1930s, the volcano was calm until its yellow vigilance of the ORSEC plan on December 4, an alert intended for scientists more than for residents.

Some 50 earthquakes occurred in the volcano in September, and 78 in November, against less than 10 earthquakes per month until 2019, then explained the Volcanological and Seismological Observatory of the island (OVSM).

Reassure the population

To reassure the population, the prefecture, the mayors and the observatory host numerous public meetings.

At the Prêcheur, the communal hall is full. A large part of the 1,500 inhabitants, anti-covid mask on the nose, waits to really understand the stakes of the yellow alert issued by the OVSM.

In the audience, a woman speaks: "I do not see why I am informed if it is only a scientific alert". "We could not have communicated", replies the sub-prefect of St Pierre and Trinité, Nicolas Onimus, specifying that this alert is shared "at the world level" between scientists to follow the evolution of the volcano. “One day, a journalist would have known that something had happened and you would have said + but what is this circus, things are being hidden from us? », He comments.

Questions arise in particular on the development of an evacuation plan, the idea of twinning the municipalities concerned in the north with others further south making their way. But we must “know exactly how many inhabitants are vulnerable, who have heavy medical treatment, who cannot leave like that,” continues Nicolas Animus.

"I don't regret being there"

Nadège, she is diabetic. For thirty-four years, this native of the south has taken up residence in the north and founded her family there. Despite his fragile health, this announcement of the passage in yellow vigilance does not scare him.

“Either way, there will always be warning signs. Me, I do not regret being there, ”she reassures herself.

Her daughters, both mothers, are less serene. They were born and raised in the shadow of the volcano .“We have always seen it as something magnificent, but knowing that it is very scary since we know what it can cause,” Xénia confides.

Her sister, Méloé is counting on “new technology. We have a lot more details on what is happening in the mountain, at the top but also at the bottom. So it's okay, ”she explains.

"Very small" earthquakes

This information on the volcano's subsoil is transmitted by the many sensors, seismic stations, and GPS installed on the sides and around the crater. To interpret them, two scientists from the OVSM take turns to monitor the slightest movement.

“There, for example, we identified a small volcano-tectonic earthquake that took place under Mount Pelée this morning,” explains Jordane Corbeau, a post-doctoral fellow in seismology at the OVSM.

“These are very small earthquakes. The instruments can see them but they are of very low magnitude and no one can smell them, ”she explains, facing a huge bay window with a breathtaking view of the Pelée. On his desk, a computer screen lined with red and green oscillations.

To support the small team of the Martinican observatory, scientists from Guadeloupe and the Institut Physique du Globe in Paris are also on alert.

Soon, as a result of the yellow vigilance, other brand new instruments, in particular drones and new GPS, will be installed to watch over the mountain.