Volcanic hazard assessment for tephra fallout in Martinique

Abstract

Mount Pelée (Martinique) is one of the most active volcanoes in the Lesser Antilles arc with more than 34 magmatic events in the last 24,000 years, including the deadliest eruption of the 20th century. The current volcanic hazard map used in the civil security plan puts the emphasis on the volcanic hazard close to the volcano. This map is however based on an incomplete eruptive history and does not take into account the variability of the expected source conditions (mass eruption rate, total erupted mass, and grain-size distribution) or the wind effect on ash dispersal. We propose here to refine the volcanic hazard map for tephra fallout by using the 2-D model of ash dispersal HAZMAP. We first simulate the maximum expected eruptive scenario at Mount Pelée (i.e., the P3 eruption) using a seasonal wind profile. Building upon the good agreement with field data, we compute probability maps based on this maximum expected scenario, which show that tephra fallout hazard could threaten not only areas close to the volcano but also the southern part of Martinique. We then use a comprehensive approach based on 16 eruptive scenarios that include new field constraints obtained in the recent years on the past Plinian eruptions of Mount Pelée volcano. Each eruptive scenario considers different values of total erupted mass and mass eruption rate, and is characterized by a given probability of occurrence estimated from the refined eruptive history of the volcano. The 1979-2019 meteorological ERA-5 database is used to further take into account the daily variability of winds. These new probability maps show that the area of probable total destruction is wider when considering the 16 scenarios compared to the maximum expected scenario. The southern part of Martinique, although less threatened than when considering the maximum expected scenario, would still be impacted both by tephra fallout and by its high dependence on the water and electrical network carried from the northern part of the island. Finally, we show that key infrastructures in Martinique (such as the international airport) have a non-negligible probability of being impacted by a future Plinian eruption of the Mount Pelée. These results provide strong arguments for and will support significant and timely reconceiving of the emergency procedures as the local authorities have now placed Mount Pelée volcano on alert level yellow (vigilance) based on increased seismicity and tremor-type signals.

Modeling staged and simultaneous evacuation during a volcanic crisis of La Soufrière of Guadeloupe (France)

“…16 The current plan envisages a preventive and staged evacuation in less than 24 h. The first hours of the evacuation will be spent preparing the evacuation of the population (stopping activities, traffic control signs, identification of vulnerable people, etc.). For the phased evacuation strategy, the administrative boundary of the municipality is used as the unit of zones and the sequence starts with the evacuation of the most vulnerable municipality within the full area to be evacuated based on the volcanic hazard map of Guadeloupe 8,78 (see Figure 1, bottom left). Municipalities evacuate one by one every hour.…”

“…We thank Audrey-Michaud Dubuy and Guillaume Carazzo and the PREST INTERREG Project (PI: IPGP) for providing tephra fallout simulation results as part of their modeling of a series of eruptive scenarios for potential eruption of La Soufrie `re of Guadeloupe and Montagne Pele ´e. 78 Volcanological data used in the chracterization of the hazards were acquired thanks to recurrent funding from the IPGP and the Service national d'observation en volcanologie (SNOV) of CNRS-INSU, the EUROVOLC EU project and the ANR CASAVA ANR-RISK-09-002 project (2010-2014; https://sites.google.com/site/ casavaanr/accueil-du-projet-casava-programme-anr-risknat).…”

A GIS-based multi-hazard assessment at the San Pedro volcano, Central Andes, northern Chile

“…Most model-based volcanic hazard assessments focus on a single type of volcanic phenomena, for example, tephra fallout (Biass and Bonadonna, 2013;Biass et al, 2014Biass et al, , 2016aBiass et al, , 2017Bonasia et al, 2014;Sandri et al, 2016;Selva et al, 2018;Vásquez et al, 2019;Hayes et al, 2020;Michaud-Dubuy et al, 2021;Tadini et al, 2022;Titos et al, 2022) or PDCs (Sandri et al, 2018;Tierz et al, 2018;Charbonnier et al, 2020;Clarke et al, 2020;Esposti Ongaro et al, 2020;Flynn and Ramsey, 2020;Spiller et al, 2020). Double-hazard assessments focus on tephra fallout along with other types of volcanic phenomena, such as lava flows (Marrero et al, 2019;Gjerløw et al, 2022) or PDCs (Alcorn et al, 2013;Tennant et al, 2021).…”