The speech of a scientist, a careful reading

In no way do I claim expertise, but some of you may struggle to understand certain acronyms and concepts used by Fabrice FONTAINE. Don’t worry, you will find them explained at the bottom of the reading. 😉⏬

How is our dear Madame PELÉE doing?

Hello Mr. FONTAINE, and thank you for accepting our invitation. We would like to talk to you about our dear Madame Pelée. But first, let’s focus on you.

– How does one become the Director of a volcanological observatory? In other words, can you tell us about your career path in a few lines ?

-I completed a Bachelor’s degree at the Ecole Normale Supérieure in Lyon, followed by a Master’s degree, a DEA, and a PhD in geophysics at the University of Montpellier II. During my PhD, as part of a study on the Galápagos, I spent five months at the University of Oregon. I then completed a post-doctorate in seismology at an Australian university, The Australian National University (Canberra), and obtained a habilitation à diriger les recherches in 2016. My area of expertise is seismology. From September 2009 to August 2020, I was a lecturer at the University of Reunion in the GeoSciences Reunion Laboratory and a member of the Volcanic Systems team at the Institute of Physics of the Globe of Paris (IPGP). I started my position as the new Director and Scientific Manager of the Martinique Volcanological and Seismological Observatory (OVSM) of IPGP on September 1, 2020.

Now let’s get back to the heart of the matter, Mount Pelée.

– How old is Mount Pelée approximately ?

– The estimated age of this volcano is 550,000 years old.

– Could she be as old as the creation of our island, Martinique ?

– Mount Pelée is not the oldest part of Martinique. In fact, the oldest parts of the island are located in La Caravelle and Sainte-Anne and are dated between 21 and 25 million years old.

– Currently, how is our dear Mount Pelée doing ?

– Since April 2019, we have been witnessing a seismic reactivation associated with diffuse CO2 emissions through the ground, which indicate a significant change in the hydrothermal-magmatic system of Mount Pelée. The evolution of the volcano can follow different scenarios that cannot be predicted with certainty, which requires increased scientific and societal vigilance.

– How is it different from the Pitons du Carbet or Montagne du Vauclin ?

– Mount Pelée is currently the only active volcano in Martinique, and its formation is more recent than that of the Pitons du Carbet, which likely began between 1 and 2 million years ago. In contrast, Montagne du Vauclin is even older. The Vauclin-Pitault range is between 8 and 16 million years old.

**– In order to check its health status, and in view of the population, what are the indicators that you rely on daily ? **

– We rely on several parameters such as:

• the number of earthquakes and the magnitude of the different types of volcanic earthquakes, allowing us to evaluate the seismic energy released;
• the location of earthquakes;
• the migration of seismicity in space but also in depth;
• the type of earthquake and their frequency content which reflects whether they correspond to rock fracturing processes (volcano-tectonic earthquakes with high frequencies), or for example to the circulation of volcanic fluids (seismicity with low frequencies) such as gas, water, or overpressured magma inside the volcanic edifice. Currently, there are no observations indicating that magma is rising inside the volcanic edifice of Mount Pelée;
• the appearance of new types of volcanic earthquakes ;
• whether volcanic seismicity is felt or not ;
• the detection of deformation of the edifice (which is not currently the case) ;
• the level of aquifers in the volcano ;
• monitoring of surface fractures ;
• monitoring of multiple parameters of thermal springs such as pH, conductivity, temperature, and composition ;
• the concentration, flux, and composition of diffuse soil degassing;
• the presence of degraded and dead vegetation zones ;
• the appearance of fumaroles and their chemical composition (which is not currently the case);
• the variation of flow rate of thermal springs;
• the landslides on the slopes of the 1929-1932 dome ;
• the foul odor (of H2S) felt in inhabited areas and the blackening of silverware near the volcano (which is not currently the case). – From which indicators would you estimate any danger to the Martinican population ?

– In case of a strong and rapid increase, even exponential increase, of observed parameters such as the following:

• Increase in felt volcanic seismicity ;
• Increase in low-frequency seismicity ;
• Appearance of connectivity in the location of earthquakes between the surface and magmatic storage areas ;
• Increase in the number and intensity of phreatic explosions
• ;
• Significant swelling of the volcanic edifice detected by deformation sensors (deep source, migration of the source towards the surface) ;
• Abnormal variation in water level in wells
• ;
• Thermal anomaly of the ground ;
• Increase in the temperature of fumaroles ;
• Appearance of SO2 degassing and injection of deep gases, abrupt variations in gas flux ;
• Incandescence at the summit and in other areas ;
• Development of fractures and landslides on the surface.

– Does observing animals in the surrounding area come into play in your analysis ?

– A phreatic explosion could be responsible for the death of animals, as was the case following the phreatic explosion of January 1792, which caused the death of several birds. A significant release of CO2 gas from the ground (high concentration, high flux) can lead to an accumulation of this gas in low-lying and poorly ventilated areas, which can affect the health of animals.

– What are the main animal behaviors that could alert to an imminent danger ?

– The fleeing of many animals in the volcano area could be related to a change in the ecosystem of these animals. However, its origin is very variable and its occurrence is not necessarily associated with a change in the activity of a volcano. Scientists use data from monitoring networks and knowledge of past and possible activity for this type of volcano, using analog volcanoes, as there are also gaps in knowledge (possible phenomena but not yet observed).

**– In case of danger, what are the guidelines to follow ? **

– Depending on the volcanic hazard considered (pyroclastic flow, lahars, explosive eruption, projection of blocks, volcanic ash fall), videos from the VolFILM, international project, funded by the World Bank, are available in several languages, including French thanks to the collaboration of the Paris Institute of Global Physics. They describe these phenomena and the attitudes to adopt in the case of a lahar or pyroclastic flow, ash fall.

Pedagogical and informative brochures in French produced by IVHHN (International Volcanic Health Hazard Network), in collaboration with the Paris Institute of Global Physics, are also available :

• Guide to preventive measures to be followed before, during, and after volcanic ash fall

• Guide for the public on the health risks of volcanic ash.

– Are the municipalities most exposed to the risk of an eruption informed of the recommendations to follow? Is there, as for earthquakes, cyclones, tsunamis, and other natural phenomena, a program to put the most at-risk populations in a situation ?

– Indeed, there is the civil security response organization plan (OrSec) for volcanic phenomena of Mount Pelée under the responsibility of the Prefect of Martinique..

– Sometimes, mudflows, also called lahars, are observed in Le Prêcheur. How should we interpret these phenomena? Are they dangerous for the surrounding population ?

– This term, of Indonesian origin, refers to a muddy flow with volcanic rock debris of all sizes as well as mud. Lahars form quickly, they follow valleys and grow by eroding material in the valley and when merging with other rivers. Lahars can represent a threat to the surrounding population. They can form in relation to an eruption (before, during, or after) or without any relation to eruptive activity (as is currently the case in the Prêcheur River). The Prêcheur River is equipped with an automatic lahar detection system. This device consists of a main system that includes three geophones and a secondary system for detecting the strongest flows based on pendulum sensors. These sensors were installed by the observatory at the end of 1999, following mudflows in January 1997 and 1998, inspired by existing systems in other volcanic observatories, such as the one operated by the USGS on volcanoes in the Cascades in the United States. In the event of a lahar caused by the remobilization of sedimentary deposits generated by one or more previous landslides – at the Samperre cliff level – cthis system automatically triggers the ringing of a siren in the town of Le Prêcheur.

– In conclusion, what would be the final words ?

– This volcano is now monitored by several modern monitoring networks of the Volcanological and Seismological Observatory of Martinique belonging to the Institute of Earth Physics of Paris. Good news for us scientists, but also for the population: knowledge of its eruptive past and volcanic processes has greatly increased in recent decades. This observatory is one of three French volcanological observatories (the Volcanological and Seismological Observatory of Martinique, the Volcanological and Seismological Observatory of Guadeloupe, and the Volcanological Observatory of Piton de la Fournaise). All three are part of the Institute of Earth Physics of Paris. With its Volcanological Observatory of Piton de la Fournaise, IPGP also operates, since 2019, the REVOSIMA (Volcanological and Seismological Surveillance Network of Mayotte), in co-responsibility with BRGM, and in partnership with IFREMER, CNRS, and many universities and institutes, within a consortium.

On behalf of Martinique Airlocal, I thank you for your availability and involvement, and wish you good luck in your research.

Petit lexique Do you not understand an acronym or concept? You are in the right place. 😊

DEA • Diploma of Advanced Studies

OVSG • Volcanological and Seismological Observatory of Guadeloupe

OVPF • Volcanological Observatory of Piton de la Fournaise

CO2 • Carbon dioxide

PH • Hydrogen potential

H2S • Hydrogen sulfide

SO2 • Sulfur dioxide

USGS • United States Geological Survey

BRGM • Bureau of Geological and Mining Research

IFREMER • French Research Institute for Exploitation of the Sea

CNRS • National Center for Scientific Research

Fumarole or fumerole • Emission of gas escaping from a volcano.

Phreatic explosion • Volcanic explosion is characterized by the violent expulsion of a large mass of water from the ground in the form of explosions. The consequence is the formation of a volcanic plume containing exclusively water vapor, fine droplets of condensed water, and possibly volcanic gases.

Pyroclastic • Referring to a rock formed by volcanic projections (a mixture of volcanic gases, water vapor, and solid particles at high temperatures).

Geophone • A sensor that records and/or measures the speed of seismic vibrations or micro-vibrations through the ground. This tool is different from an accelerometer and a seismometer (sensors that detect ground movements).

This exchange was very fruitful. On the one hand, I went back to school 👩🏽‍🎓📚. Having followed a literary path, and I’m not going to lie, there were some concepts that I didn’t remember or that seemed very distant to me #TeamLEtesVousLa. On the other hand, and even though I suppose that in the event of such a catastrophe, it will be chaos guaranteed 😱, a little like in all the action movies about the end of the world, I am still happy to see that there are advances and measurement tools to alert us 😌.

I even feel like I’m more protected in this area than regarding the poisoning of chlordane or everything that’s currently happening.

Anyway 😏, I’m going back to my Care Bears world. ⛅🌟🌈💖

See you soon.