Can rainfall trigger volcanic eruptions? A mechanical stress model of an active volcano: ‘Piton de la Fournaise’, Reunion Island |
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| Authors: | S Violette G de Marsily J P Carbonnel P Goblet E Ledoux S M Tijani & G Vouille |
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| Institution: | Laboratoire de Géologie Appliquée, U.PM.C.-Paris VI, France;Centre d'Informatique Géologique, ENSMP, 35 rue Saint-Honoré, 77305 Fontainebleau, France;Centre de Géotechnique et d'Exploitation du Sous-sol, ENSMP, 35 rue Saint-Honoré, 77305 Fontainebleau, France |
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| Abstract: | This paper relates the hydrology of a volcano to its eruptive activity, which seem to be correlated. Based on the groundwater pattern previously determined by hydrologic and thermal modelling, we formulate hypotheses for the mechanisms linking rainfall and volcanic eruptions. We focus on: mechanical loading by the weight of the infiltrated rain, which might favour magma overpressure or slope instability on the eastern volcanic flank; unloading of the infiltrated water, discharged toward the ocean, which could increase the tangential tensile stress above the magma chamber. We test the sensitivity of the model to the magma chamber geometry and the rainfall distribution. The mechanical unloading of the infiltrated water is the mechanism most likely to trigger eruptions. However, the presence of a sliding surface and rainfall loading could favour the development of tensile stress in the 'shell' surrounding the magma chamber but with a lower intensity than in the previous case. |
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