Effusive crises at Piton de la Fournaise 2014–2015: a review of a multi-national response model

Abstract

Many active European volcanoes and volcano observatories are island-based and located far from their administrative "mainland". Consequently, Governments have developed multisite approaches, in which monitoring is performed by a network of individuals distributed across several national research centers. At a transnational level, multinational networks are also progressively emerging. Piton de la Fournaise (La Réunion Island, France) is one such example. Piton de la Fournaise is one of the most active volcanoes of the World, and is located at the greatest distance from its "mainland" than any other vulnerable "overseas" site, the observatory being 9365 km from its governing body in Paris. Effusive risk is high, so that a well-coordinated and rapid response involving near-real time delivery of trusted, validated and operational product for hazard assessment is critical. Here we review how near-real time assessments of lava flow propagation were developed using rapid provision, and update, of key source terms through a dynamic and open integration of near-real time remote sensing, modeling and measurement capabilities on both the national and international level. The multi-national system evolved during the five effusive crises of 2014-2015, and is now mature for Piton de la Fournaise. This review allows us to identify strong and weak points in an extended observatory system, and demonstrates that enhanced multi-national integration can have fundamental implications in scientific hazard assessment and response during an on-going effusive crisis.

Constraining Spatiotemporal Characteristics of Magma Migration at Piton De La Fournaise Volcano From Pre‐eruptive Seismicity

“…Indeed, a major concern are distal flank eruptions close to inhabited areas outside of the Enclos Fouqué caldera. In addition, as the volcano is a popular tourist attraction (with over 350,000 visitors per year; Harris et al, 2017), the prediction of eruptive fissure location is important to plan the evacuation of visitors hiking into the caldera. Eruptions are generally preceded by an intense shallow seismic crisis lasting a few hours (Roult et al, 2012), which originates from a persistent structure located below the volcano summit around sea level (Lengliné et al, 2016;Sapin et al, 1996).…”

Thermal Remote Sensing for Global Volcano Monitoring: Experiences From the MIROVA System

“…Stationary, waning or intensifying trends obviously have different implications on the evaluation of the hazards and can be used (modeled) to define future eruptive scenarios, and possibly to make forecasts. At Piton de la Fournaise (La Réunion Island), the knowledge of the effusion rate trend (derived from thermal data), in combination with previously generated models of the likely lava flow path, has been useful to predict whether the flow will tend to lengthen or shorten, and whether the lava flows will reach the sea, cutting the national road that goes around La Réunion Island (Harris et al, 2017(Harris et al, , 2019. Moreover, by comparing this variable with the gas flux and deformation rate, it is possible to analyze the balance of the erupted/degassed material and eventually to quantify magmatic intrusions or endogenous growth .…”

“…At basaltic volcanoes equipped with a large ground-based monitoring network, such as Stromboli, Etna, Piton de la Fournaise, etc., MIROVA is commonly used to estimate timeaveraged lava discharge rates (TADR) and erupted volumes in near real time Laiolo et al, 2019), to define imminent eruptive scenarios and to model the path and length of lava flows (Harris et al, 2017(Harris et al, , 2019.…”

“…Taking into account the uncertainty in the TADR estimates (typically between 30 and 50%; Coppola et al, 2019b), several types of predictions are possible. For example, the initial flow rate (Q 0 ) can be used (as soon as the MODIS data has been processed) within an effusive response protocol (Harris et al, 2017(Harris et al, , 2019, to timely provide the observatory flow path projections and maximum run-out of the emplacing lava flow (Figure 8b).…”

Evidences of Plug Pressurization Enhancing Magma Fragmentation During the September 2016 Basaltic Eruption at Piton de la Fournaise (La Réunion Island, France)

“…These eruptions were mostly typical basaltic fissure eruptions with a few exceptions like the summit ash emission linked with the collapse of the Dolomieu summit caldera (Figure 1) during the April 2007 eruption (e.g., Michon et al, 2013;Peltier et al, 2009;Staudacher et al, 2009Staudacher et al, , 2016, which involved more magma than any other eruption at PdF since at least 200 years. Since, the eruptive regime at PdF has been mainly effusive, coupled with more or less intense Hawaiian-style and weak Strombolian-style activity (e.g., Gurioli et al, 2018;Harris et al, 2017;Peltier et al, 2018). Weak Strombolian-style activity at PdF is mainly characterized by short and sporadic bubble bursts that only form coarse lapilli, bombs and spatters with scarce ash emission (DynVolc 2017; Gurioli et al, 2018), while Hawaiian-style fragmentation is characterized by moderate sustained lava fountains, following the classification of Houghton et al (2016), and usually produce lapilli and coarse ash sometimes with Pele's hairs (e.g., Di Muro et al, 2014Gurioli et al, 2018;Villemant et al, 2009).…”