Stress Field Control during Large Caldera-Forming Eruptions

Abstract

Crustal stress field can have a significant influence on the way magma is channeled through the crust and erupted explosively at the surface. Large Caldera Forming Eruptions (LCFEs) can erupt hundreds to thousands of cubic kilometers of magma in a relatively short time along fissures under the control of a far-field extensional stress. The associated eruption intensities are estimated in the range 10 9 -10 11 kg/s. We analyse syn-eruptive dynamics of LCFEs, by simulating numerically explosive flow of magma through a shallow dyke conduit connected to a shallow magma (3-5 km deep) chamber that in turn is fed by a deeper magma reservoir (>∼10 km deep), both under the action of an extensional far-field stress. Results indicate that huge amounts of high viscosity silicic magma ( 10 7 > Pa s) can be erupted over timescales of a few to several hours. Our study provides answers to outstanding questions relating to the intensity and duration of catastrophic volcanic eruptions in the past. In addition, it presents far-reaching implications for the understanding of dynamics and intensity of large-magnitude volcanic eruptions on Earth and to highlight the necessity of a future research to advance our knowledge of these rare catastrophic events.

Understanding the plume dynamics of explosive super-eruptions

“…Our results have enormous implications for the assessment of the dynamics of super-eruptions. For the most extreme MFRs 13 , ~10 11 kg/s, similar to those estimated for the Young Toba Tuff (YTT) eruption 4 , the total plume height increases beyond the stratosphere (up to ~60–70 km) owing to the development of local over-plumes above the umbrella region, even though the NBL remains at ~20 km. The bulk mass spreads in the umbrella region between ~20 and ~50 km, and the local over-plumes develop above the main umbrella region (see Supplementary Figure 1 ).…”

“…Estimates of mass flow rates (MFRs) during these super-eruptions, obtained from different independent approaches, suggest that they are extremely high, ranging from 10 9 to 10 11 kg/s 4 , 8 , 10 – 12 . Such large MFRs require multiple vents or continuous emission along dykes 13 , 14 .…”

Seismological constraints on the 2018 Mt. Etna (Italy) flank eruption and implications for the flank dynamics of the volcano

“…As known, in volcanic environments the analysis of the stress field represents a valuable approach to infer the volcano dynamics (Costa & Marti, 2016; Gudmundsson, Acocella, & Vinciguerra, 2009; Hardebeck & Michael, 2006; Massa, D’Auria, Cristiano, & De Matteo, 2016; Plateaux, Bèthoux, Bergerat, & Lèpinay, 2014; Wyss, Habermann, & Bodin, 1992). Indeed, the stress changes play a key role in driving magmas and/or fluids migration within the shallow crust.…”

Determining the Stress Field in Active Volcanoes Using Focal Mechanisms

“…In volcanic environments, a spatio-temporal analysis of the stress fields represents a valuable approach to infer the volcano dynamics (Wyss et al, 1992;Hardebeck and Michael, 2006;Gudmundsson et al, 2009;Plateaux et al, 2014;Costa and Marti, 2016). Stress field variations play a key role in driving magmas and/or fluids migration.…”