New physical characterization of the Fontana Lapilli basaltic Plinian eruption,Nicaragua |
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| Authors: | L Costantini C Bonadonna B F Houghton H Wehrmann |
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| Institution: | (1) Departement de Mineralogie, Université de Genève, Rue des Maraichers 13, 1205 Geneva, Switzerland;(2) University of Hawaii at Manoa, Honolulu, HI, USA;(3) IfM-Geomar/SFB 574, Kiel, Germany |
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| Abstract: | The Fontana Lapilli deposit was erupted in the late Pleistocene from a vent, or multiple vents, located near Masaya volcano
(Nicaragua) and is the product of one of the largest basaltic Plinian eruptions studied so far. This eruption evolved from
an initial sequence of fluctuating fountain-like events and moderately explosive pulses to a sustained Plinian episode depositing
fall beds of highly vesicular basaltic-andesite scoria (SiO2 > 53 wt%). Samples show unimodal grain size distribution and a moderate sorting that are uniform in time. The juvenile component
predominates (> 96 wt%) and consists of vesicular clasts with both sub-angular and fluidal, elongated shapes. We obtain a
maximum plume height of 32 km and an associated mass eruption rate of 1.4 × 108 kg s−1 for the Plinian phase. Estimates of erupted volume are strongly sensitive to the technique used for the calculation and to
the distribution of field data. Our best estimate for the erupted volume of the majority of the climactic Plinian phase is
between 2.9 and 3.8 km3 and was obtained by applying a power-law fitting technique with different integration limits. The estimated eruption duration
varies between 4 and 6 h. Marine-core data confirm that the tephra thinning is better fitted by a power-law than by an exponential
trend. |
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| Keywords: | Basaltic Plinian eruption Masaya volcano Eruption parameters Volcanic hazards Explosive volcanism Volume calculation Tephra deposition |
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