OVSM-IPGP recommends Mount Pelée to be placed under yellow volcanic watch
On Thursday December 3rd, the Martinique Volcanological and Seismological Observatory of the IPGP (Institut de Physique du Globe de Paris, CNRS) sent an explanatory note to the Prefect of Martinique, recommending that Montagne Pelée be upgraded to yellow volcanic alert (2nd alert level on a scale of 4).
Mount Pelee © IPGP
Publication date: 04/12/2020
General public, Observatories, Press, Research
Related observatories : Volcanological and Seismological Observatory of Martinique (OVSM-IPGP)
Related themes : Natural Hazards
This recommendation by the OVSM-IPGP follows the detection of changes in seismic signals measured as part of the observatory’s monitoring of the volcano, and consultation with a group of experts who have studied these phenomena.
Located to the north of the island of Martinique, Montagne Pelée, a stratovolcano linked to the subduction zone of the Lesser Antilles, has seen at least 4 eruptions in the last 250 years: phreatic eruptions without magma input in 1792 and 1851, and two magmatic eruptions, including the infamous eruption from 1902 to 1905 and the last one from 1929 to 1932.
- Since the introduction of modern observation networks in 1980, volcanic seismicity beneath Montagne Pelée has typically been very low, with an average of just a few dozen earthquakes recorded each year. Swarms of earthquakes have already been clearly recorded in 1980, 1985-1986, 2007 and 2014. However, the 2007 and 2014 swarms were directly linked to high-magnitude earthquakes in the Caribbean arc. The increase in seismicity of superficial volcanic origin (up to 4-5 km below the summit) observed since April 2019 is therefore clearly above the baseline level characteristic of Montagne Pelée. Although this seismicity could be linked to the gradual increase in seismicity on a regional scale (research work is underway), which would disrupt the volcano’s stress field, it is clearly not associated with major tectonic earthquakes such as in 2007 and 2014. This increase could therefore also be the result of changes in the activity of the hydrothermal system beneath Montagne Pelée.
- In addition, in April 2019, volcanic seismicity appeared at depth around and beneath Montagne Pelée (more than 10 km below sea level). This could correspond to the arrival of magmatic fluids at depth.
- Lastly, new tremor-like signals were observed on 8 and 9 November 2020: they could correspond to a reactivation of the hydrothermal system. Research is underway to better determine the processes behind these signals, and in particular the possible influence of heavy rainfall during this period.
Even if, in the current state of measurements, there is no deformation of the volcano on the scale of the observation network, the appearance, in a few months, of these three different types of seismic signals of volcanic origin shows a clear change in the behaviour of the volcanic system, whose activity is increasing compared with the basic level observed over several decades.
As a result, the OVSM-IPGP, after discussions with a group of around twenty experts from the institute, is increasing its vigilance and recommending that the alert level be raised to yellow.
This change to yellow volcanic alert means that the observation resources deployed by the OSVM will be stepped up and additional resources (human and instrumental) will be mobilised at the IPGP in order to better monitor and analyse the functioning and evolution of the volcanic system in real time.
The Prefecture of Martinique has followed this recommendation and the Montagne Pelée area will be placed on yellow volcanic alert from 4 December 2020.
