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Propagation and arrest of the May 2021 lateral dike intrusion at Nyiragongo (D.R. Congo)
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  • Delphine Smittarello,
  • Julien Barrière,
  • Nicolas d'Oreye,
  • Benoit Smets,
  • Adrien Oth,
  • Tara Shreve,
  • Josue Subira,
  • Blaise Mafuko Nyandwi,
  • Valerie Cayol,
  • Raphael Grandin,
  • Christelle Wauthier,
  • Dominique Derauw,
  • Halldor Geirsson,
  • Nicolas Theys,
  • François Darchambeau,
  • Sam Poppe,
  • Patrick Allard,
  • Corentin Caudron,
  • Philippe Lesage,
  • Sergey Samsonov,
  • Louise Delhaye,
  • Magdalena Oryaëlle Chevrel,
  • Niche Mashagiro,
  • Adalbert Muhindo Syavulisembo,
  • Francois Kervyn
Delphine Smittarello
European Center for Geodynamics and Seismology

Corresponding Author:delphine.smittarello@ecgs.lu

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Julien Barrière
European Center for Geodynamics and Seismology
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Nicolas d'Oreye
National Museum of Natural History
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Benoit Smets
Royal Museum for Central Africa
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Adrien Oth
European Center for Geodynamics and Seismology
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Tara Shreve
Carnegie Institution for Science
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Josue Subira
Goma Volcano Observatory
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Blaise Mafuko Nyandwi
Royal Museum for Central Africa
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Valerie Cayol
Lyon University
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Raphael Grandin
Université de Paris, Institut de Physique du Globe de Paris, CNRS
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Christelle Wauthier
The Pennsylvania State University
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Dominique Derauw
Centre Spatial de Liège
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Halldor Geirsson
University of Iceland
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Nicolas Theys
Royal Belgian Institute for Space Aeronomy
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François Darchambeau
Université de Liège
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Sam Poppe
Université Libre de Bruxelles
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Patrick Allard
CNRS
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Corentin Caudron
Institut de Recherche et de Développement (IRD)
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Philippe Lesage
ISTerre Institute of Earth Sciences
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Sergey Samsonov
Natural Resources Canada
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Louise Delhaye
Royal Museum for Central Africa
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Magdalena Oryaëlle Chevrel
Université Clermont-Auvergne
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Niche Mashagiro
Goma Volcano Observatory
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Adalbert Muhindo Syavulisembo
Goma Volcano Observatory
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Francois Kervyn
Royal Museum for Central Africa
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Abstract

On the 22nd of May 2021, although no alarming precursory unrest had been reported, Nyiragongo volcano erupted and lava flows threatened about 1 million of inhabitants living in the cities of Goma (Democratic Republic of Congo) and Giseny (Rwanda). After January 1977 and January 2002, it was the beginning of the third historically known flank eruption of Nyiragongo volcano and the first ever to be recorded by dense measurements both on the ground and from space. In the following days, seismic and geodetic data as well as fracture mapping revealed the gradual southward propagation of a shallow dike from the Nyiragongo edifice underlying below Goma airport on May 23-24, then Goma and Gisenyi city centers on May 25-26 and finally below the northern part of Lake Kivu on May 27. Southward migration of the associated seismic swarm slowed down between May 27 and June 02. Micro seismicity became more diffuse, progressively activating transverse tectonic structures previously identified in the whole Lake Kivu basin. Here we exploit ground based and remote sensing data as well as inversion and physics-based models to fully characterize the dike sized, the dynamics of dike propagation and its arrest against a structural lineament known as the Nyabihu Fault. This work highlights the shallow origin of the dike, the segmented dike propagation controlled by the interaction with pre-existing fracture networks and the incremental crater collapse associated with drainage which led to the disappearance of the world’s largest long-living lava lake on top of Nyiragongo.