Réunion | INSTITUT DE PHYSIQUE DU GLOBE DE PARIS

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  Réunion

 

PGP researchers performed a lot of studies in La Reunion linked to the permanent observatory OVPF. For several years, the seismology team has been leading scientific and field works to better understand the volcanic and gravitational activities on the volcano. After the installation of permanent seismic stations within the ANR UNDERVOLC (Florent Brenguier), seismic antennas and video cameras have been installed in July 2015 by the European ERC SLIDEQUAKES (Anne Mangeney). The objective of this project is to detect, characterize and monitor the recurrent rockfall activity in the crater and to study its link with the volcanic activity. Indeed, recent works suggest that the characteristics of rockfalls, generated by the crater wall weakening, may provide information on the nature of future eruptions. The Dolomieu crater is a unique large scale laboratory for gravitational flows because of the high frequency of rockfall events and of the simple topography over which they are flowing. The rockfalls are currently detected, localized and their volume is calculated from the recorded seismic energy. They are also recorded by video cameras. These data together with the scanner-laser measurements of the crater topography performed by the ERC SLIDEQUAKES provide unique data to characterize the dynamics of gravitational flows and to follow their time change in relation to external forcing. Besides, our seismic/photogrammetric studies in link with acoustic and geochemical methods made it possible to calculate the magma flux from the generated seismic signal. This has a strong potential impact for quantification of the time change of the flux of magma emitted by a volcano during an eruption.