New physical characterization of the Fontana Lapilli basaltic Plinian eruption, Nicaragua

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 (SiO 2 >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 × 10 8 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 km 3 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.

CO2-driven large mafic explosive eruptions: the Pozzolane Rosse case study from the Colli Albani Volcanic District (Italy)

“…Fuego, Guatemala, Davies et al 1978;Rose et al 1978;Tarawera, New Zealand, Walker et al 1984;Houghton et al 2004;Mount Etna, Coltelli et al 2005; Nicaragua, Costantini et al 2009) and even basaltic welded ignimbrite associated with caldera collapse (Gran Canaria, Freundt and Schmincke 1995), the products of major explosive eruptions from the ultrapotassic Colli Albani Volcanic District (Roman Province, Italy) represent the most noticeable exception (Fig. 1).…”

Mafic Plinian eruptions: Is fast ascent required?

“…The Fontana Lapilli, which erupted near Masaya volcano in the late Pleistocene (60 ka), provides the samples for part of this study [ Costantini et al ., ; Costantini et al ., ]. Wehrmann et al .…”

“…[] divided the Fontana Lapilli into seven units, labeled A–G. Units A–C, attributed to the opening stages of the eruption, are characterized by thin, moderately sorted for A, graded for B, and poorly sorted beds for C [ Costantini et al ., ; Costantini et al ., ]. The main portion of the deposit consists of units D–F and lower G, which are composed of many alternating beds of moderately sorted, massive‐to‐weakly stratified, and nongraded layers [ Costantini et al ., ; Costantini et al ., ].…”

Causes and consequences of bimodal grain-size distribution of tephra fall deposited during the August 2006 Tungurahua eruption (Ecuador)

“…Such mathematical expressions, as given below in Eqs. 1 and 2 for exponential and power laws, respectively, describe reasonably the decay rate of many other well-documented fallout deposits (Bonadonna and Houghton 2005;Rose et al 2008;Carey et al 2009;Costantini et al 2009;Watt et al 2009) .…”