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Article Dans Une Revue Bulletin of Volcanology Année : 2007

The November 2002 eruption at Piton de la Fournaise volcano, La Réunion Island: ground deformation, seismicity, and pit crater collapse

Marc-Antoine Longpré
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Thomas Staudacher
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John Stix
  • Fonction : Auteur

Résumé

Abstract An eruption on the eastern flank of Piton de la Fournaise volcano started on 16 November, 2002 after 10 months of quiescence. After a relatively constant level of activity during the first 13 days of the eruption, lava discharge, volcanic tremor and seismicity increased from 29 November to 3 December. Lava effusion suddenly ceased on 3 December while shallow earthquakes beneath the Dolomieu summit crater were still recorded at a rate of about one per minute. This unusual activity continued and increased in intensity over the next three weeks, ending with the formation of a pit crater within Dolomieu. Based on ground deformation, measured by rapid-static and continuous GPS and an extensometer, seismic data, and lava effusion patterns, the eruptive period is divided into five stages: 1) slow summit inflation and sporadic seismicity; 2) rapid summit inflation and a short seismic crisis; 3) rapid flank inflation, onset of summit deflation, sporadic seismicity, accompanied by stable effusion; 4) flank inflation, coupled with summit deflation, intense seismicity, and increased lava effusion; and finally 5) little deflation, intense shallow seismicity, and the end of lava effusion. We propose a model in which the pre-intrusive inflation of Stage 1 in the months preceding the eruption was caused by a magma body located near sea level. The magma reservoir was the source of an intrusion rising under the summit during Stage 2. In Stage 3, the magma ponded at a shallow level in the edifice while the lateral injection of a radial dike reached the surface on the eastern flank of the basaltic volcano, causing lava effusion. Pressure decrease in the magmatic plumbing system followed, resulting in upward migration of a collapse front, forming a subterranean column of debris by faulting and stoping. This caused intense shallow seismicity, increase in discharge of lava and volcanic tremor at the lateral vent in Stage 4 and, eventually the formation of a pit crater in Stage 5.

Dates et versions

hal-00311769 , version 1 (21-08-2008)

Identifiants

Citer

Marc-Antoine Longpré, Thomas Staudacher, John Stix. The November 2002 eruption at Piton de la Fournaise volcano, La Réunion Island: ground deformation, seismicity, and pit crater collapse. Bulletin of Volcanology, 2007, 69 (5), pp.511-525. ⟨10.1007/s00445-006-0087-0⟩. ⟨hal-00311769⟩
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