Pitons, cirques and remparts of Reunion Island

World Heritage Research

Discover scientific research and academic studies that deepen our understanding of Pitons, cirques and remparts of Reunion Island from its history and significance to its conservation, management, and contemporary challenges.

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

  During the September 2016 eruption of Piton de la Fournaise volcano on Réunion Island, a sudden shift from typical effusive activity to explosive ash and bomb emission occurred. This transition was linked to the pressurization of a degassed, cooled magma plug beneath a secondary vent (Vent B), which enhanced magma fragmentation. The study integrated geophysical data with textural and petrological analyses, revealing that the explosive phase involved denser, crystal-rich tephra (sideromelane and tachylite) alongside more gas-permeable, vesicular fragments (golden pumice and fluidal scoria). Permeability measurements and chemical analyses suggested that the sideromelane and tachylite components originated from subsurface crystallization of the initial magma types. This finding highlights the potential danger posed by such transitions in volcanic activity, particularly for tourist areas accustomed to 'gentle' eruptions.

  Thivet, S., Gurioli, L., Di Muro, A., Derrien, A., Ferrazzini, V., Gouhier, M., Coppola, D., Galle, B., & Arellano, S. (2020). Evidences of Plug Pressurization Enhancing Magma Fragmentation During the September 2016 Basaltic Eruption at Piton de la Fournaise (La Réunion Island, France). Geochemistry, Geophysics, Geosystems, 21(2). Portico. https://doi.org/10.1029/2019gc008611

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• The 2007 caldera collapse of Piton de la Fournaise volcano: Source process from very-long-period seismic signals

  In April 2007, Piton de la Fournaise volcano on Réunion Island experienced its largest caldera collapse in at least 300 years, characterized by a series of 48 subsidence increments with seismic signals equivalent to magnitudes Mw 4.4 to 5.4. Analysis of these very-long-period (VLP) seismic events revealed a piston-like mechanism driven by the contraction of the magma reservoir and the collapse of the overlying rock column. The study found that the collapse dynamics were primarily controlled by rapid magma withdrawal, likely from a bubbly state, leading to an acceleration in subsidence increments—a pattern similar to the 2018 Kīlauea collapse. This suggests that such events are linked to progressive weakening of the volcanic edifice and increasing rates of magma extraction.

  Duputel, Z., & Rivera, L. (2019). The 2007 caldera collapse of Piton de la Fournaise volcano: Source process from very-long-period seismic signals. Earth and Planetary Science Letters, 527, 115786. https://doi.org/10.1016/j.epsl.2019.115786

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• Control of source fertility on the eruptive activity of Piton de la Fournaise volcano, La Réunion

  Research on Piton de la Fournaise volcano, Réunion Island, reveals that its eruptive activity is directly linked to the fertility of its mantle source. The study demonstrates that decadal-scale eruptive sequences are initiated by melt extraction from fertile, incompatible element-enriched veins within the plume source, while reactive flow of enriched melts increases mantle porosity, promoting further melt extraction. This dual control mechanism led to a fourfold increase in magma supply between 1998 and 2014, offering insights into similar surges at other hotspot volcanoes like Kilauea, Hawaii. The findings highlight the critical role of lithological heterogeneities in mantle plumes in regulating short-term eruptive activity.

  Vlastélic, I., Di Muro, A., Bachèlery, P., Gurioli, L., Auclair, D., & Gannoun, A. (2018). Control of source fertility on the eruptive activity of Piton de la Fournaise volcano, La Réunion. Scientific Reports, 8(1). https://doi.org/10.1038/s41598-018-32809-0

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• Uncovering the hidden signature of a magmatic recharge at Piton de la Fournaise volcano using small earthquakes

  A ring-shaped zone of weakness beneath Piton de la Fournaise volcano, revealed through advanced seismic analysis, suggests preexisting structural vulnerabilities that influence eruptive behavior. Using a template matching method, researchers detected thousands of small earthquakes in 2014 and 2015, uncovering persistent seismicity patterns linked to magma recharge. Notably, deep earthquake migration in 2015 preceded a shallow seismic swarm, indicating the formation of a hydraulic connection between deep magma sources and a near-sea-level reservoir—likely missed in past observations due to detection limitations. This study highlights how subtle seismic signals can decode volcanic processes, offering insights into the hidden dynamics shaping eruptions at UNESCO-listed Réunion Island's volcanic landscapes.

  Lengliné, O., Duputel, Z., & Ferrazzini, V. (2016). Uncovering the hidden signature of a magmatic recharge at Piton de la Fournaise volcano using small earthquakes. Geophysical Research Letters, 43(9), 4255–4262. Portico. https://doi.org/10.1002/2016gl068383

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• Improved detection of preeruptive seismic velocity drops at the Piton de La Fournaise volcano

  Researchers have identified a previously undetected preeruptive seismic velocity drop of 0.15% associated with the June 21, 2014 eruption at Piton de La Fournaise volcano on Réunion Island. This discovery was made possible by correcting seismic velocity data for pore pressure changes caused by rainfall, which had previously obscured the signal. The study used a transfer function to model the relationship between fluid pressure and seismic velocity variations, allowing for the isolation of true preeruptive signals during a period of low eruptive activity (2011–2013). This advancement improves the potential for more reliable volcanic eruption prediction by mitigating interference from environmental factors.

  Rivet, D., Brenguier, F., & Cappa, F. (2015). Improved detection of preeruptive seismic velocity drops at the Piton de La Fournaise volcano. Geophysical Research Letters, 42(15), 6332–6339. Portico. https://doi.org/10.1002/2015gl064835

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• Long‐term mass transfer at Piton de la Fournaise volcano evidenced by strain distribution derived from GNSS network

  Piton de la Fournaise, a basaltic volcano on Reunion Island, exhibits long-term mass transfer from its summit to the eastern flank, contributing to the formation of the Grandes Pentes relief. This process is evidenced by strain distribution analysis derived from a dense GNSS network installed since 2007. The study reveals that during summit deflation (2011-2014), the upper eastern flank extended eastward while the lower flank contracted, steepening the topographic slope. This deformation regime indicates progressive loading of the lower flank by the upper one, suggesting a potential instability. The research also highlights how volcanic 'pulsation'—alternating inflation and deflation—enhances rock fracturing, reduces stiffness, and increases permeability, providing insights into the volcano's structural dynamics.

  Peltier, A., Got, J.-L., Villeneuve, N., Boissier, P., Staudacher, T., Ferrazzini, V., & Walpersdorf, A. (2015). Long‐term mass transfer at Piton de la Fournaise volcano evidenced by strain distribution derived from GNSS network. Journal of Geophysical Research: Solid Earth, 120(3), 1874–1889. Portico. https://doi.org/10.1002/2014jb011738

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• Timing of a large volcanic flank movement at Piton de la Fournaise Volcano using noise-based seismic monitoring and ground deformation measurements

  A significant volcanic flank movement at Piton de la Fournaise (PdF) Volcano, La Réunion Island, was detected using noise-based seismic monitoring and ground deformation measurements. The study revealed that a large velocity reduction in seismic signals began just days before the major 2007 April 2 eruption, coinciding with widespread flank movement triggered by magma injection. This finding underscores the potential of combining seismic velocity changes with geodetic observations to monitor hazardous slope instabilities, providing critical insights for volcanic hazard assessment.

  Clarke, D., Brenguier, F., Froger, J.-L., Shapiro, N. M., Peltier, A., & Staudacher, T. (2013). Timing of a large volcanic flank movement at Piton de la Fournaise Volcano using noise-based seismic monitoring and ground deformation measurements. Geophysical Journal International, 195(2), 1132–1140. https://doi.org/10.1093/gji/ggt276

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