Tracking Magma Storage: New Perspectives From 40 Years (1980–2020) of Ground Deformation Source Modeling on Etna Volcano

Alessandro Bonaccorso,Marco Aloisi

doi:10.3389/feart.2021.638742

Alessandro Bonaccorso, Marco Aloisi

Open Access

https://doi.org/10.3389/feart.2021.638742

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Abstract

A key issue on active volcanoes is to investigate the position and characteristics of the magma reservoirs over time. The aim is to better understand the crustal magma transfer, therefore also to define the volcanic hazard and plan the mitigation strategies. Mt. Etna volcano is characterized by a lively eruptive activity with frequent major flank eruptions that can be both purely effusive and explosive-effusive. This volcano has been monitored over 40 years by ground deformation measurements. The studies and modeling of the eruptive processes through these data have mainly concerned single eruptions and the recharge phases that preceded them. In this study, for the first time, we present four decades of numerous recharge periods modeled over time by using the same typology of measurements (geodetic baselines) and the same modeling method. This uniform approach enables tracking the location of magma storage in a robust and unambiguous way during its recharging, which causes the volcano to inflate. In particular, the recharging periods that preceded the main eruptive activities were investigated. The tracking of the source positions contributes to update the representation of the shallow-intermediate plumbing system (last 10 km). Moreover, as a new result, we highlight that the recharges preceding the explosive eruptions are accompanied by a deepening over time of the centroid of the pressure source. This result opens up new scenarios on the relationship between the position of the recharging storage and the subsequent eruptive style.

Highlights

The arrival of new magma from depth and its storage in the plumbing system within intermediateshallow reservoirs characterize the recharge phases that precede the eruptions of many volcanoes
We investigated the position of the pressure centroid during the main recharging phases of the last 40 years at Etna volcano
We used the same type of deformation measurements and the same modeling method that made it possible to fix the position of the source over time in a uniform and robust approach

Summary

INTRODUCTION

The arrival of new magma from depth and its storage in the plumbing system within intermediateshallow reservoirs characterize the recharge phases that precede the eruptions of many volcanoes. It is interesting to note that this erupted volume, despite being produced by the activity of about 50 episodes of short lava fountains over 3 years, is of the same order of magnitude as that emitted by the major flank effusive eruptions After this phase of strong explosiveness in 2016–2018 there was another recharge phase (Figure 2D) that preceded the short but powerful eruption in December 2018 (Calvari et al, 2020), which in particular with its intrusion promoted a new reprise of the acceleration of the sliding of the eastern flank (i.e., De Novellis et al, 2019; Aloisi et al, 2020; Mattia et al, 2020). For this sub-interval, both EDM and GPS measurements were inverted, and we obtained a standard deviation of about 0.03 (m) using 129 baselines varying from −0.02 to +0.25 (m)

DISCUSSION

CONCLUSION

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