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Impact of the 2007 caldera collapse to eruptive variability at Piton de la Fournaise: insights from long-term satellite-retrieved effusion rate.

Adele Campus 1, Nicolas Villeneuve2,3,4, Oryaëlle Chevrel3,4,5, Aline Peltier3,4, Andrea Di Muro6, Diego Coppola1

  • Affiliations:  1 Earth Science Department, University of Turin, Turin, Italy; 2 Université de La Réunion, Laboratoire GéoSciences Réunion, F-97744 Saint Denis, France; 3 Université Paris Cité, Institut de physique du globe de Paris, CNRS, F-75005 Paris, France; 4 Observatoire Volcanologique du Piton de la Fournaise, Institut de Physique du Globe de Paris, 97418 La Plaine des Cafres, France; 5 Université Clermont Auvergne, CNRS, IRD, OPGC, Laboratoire Magmas et Volcans, 63000 Clermont-Ferrand, France; 6 Université Claude Bernard Lyon 1, Lyon, France 

  • Presentation type: Talk

  • Presentation time: Thursday 14:45 - 15:00, Room R380

  • Programme No: 3.11.7

  • Theme 3 > Session 11

Abstract

Piton de la Fournaise volcano (La Réunion island, France) is one of the world's most active effusive volcanoes, averaging two eruptions per year. In April 2007, the collapse of the Dolomieu caldera was accompanied by its largest effusive eruption of the past century, with a bulk volume of approximately 240 Mm³. This event temporarily altered the volcano's frequent effusive activity. We examine 24 years (2000--2023) of satellite thermal data from the Moderate Resolution Imaging Spectroradiometer (MODIS) and the Visible Infrared Imaging Radiometer Suite (VIIRS) to analyze effusion rate trends for 37 eruptions before and after the collapse. Our reconstructed time series and evaluation of eruptive attributes, such as total lava volumes, eruption duration, and peak effusion rates, allowed us to identify five distinct eruption groups with differing characteristics. These groups underline the complex behaviors of the Piton de la Fournaise eruptions, challenging the traditional "pressure-cooker" model usually invoked for closed-vent basaltic volcanism. Furthermore, our analysis shows that while the long-term lava output rate has remained nearly constant (~0.7 m3/s) over the last 24 years---suggesting a steady-state condition---the frequency and characteristics of eruptive groups shifted after the April 2007 caldera collapse. We propose that this collapse altered magma ascent from the shallow (upper crustal) system to the surface without affecting its overall rate. Long-term satellite-derived effusion rate assessments may improve our understanding of basaltic volcano dynamics and refine hazard assessments for frequently active volcanoes like the Piton de la Fournaise eruptions.