Anatomy of a Paroxysmal Lava Fountain at Etna Volcano: The Case of the 12 March 2021, Episode

Abstract

On 13 December 2020, Etna volcano entered a new eruptive phase, giving rise to a number of paroxysmal episodes involving increased Strombolian activity from the summit craters, lava fountains feeding several-km high eruptive columns and ash plumes, as well as lava flows. As of 2 August 2021, 57 such episodes have occurred in 2021, all of them from the New Southeast Crater (NSEC). Each paroxysmal episode lasted a few hours and was sometimes preceded (but more often followed) by lava flow output from the crater rim lasting a few hours. In this paper, we use remote sensing data from the ground and satellite, integrated with ground deformation data recorded by a high precision borehole strainmeter to characterize the 12 March 2021 eruptive episode, which was one of the most powerful (and best recorded) among that occurred since 13 December 2020. We describe the formation and growth of the lava fountains, and the way they feed the eruptive column and the ash plume, using data gathered from the INGV visible and thermal camera monitoring network, compared with satellite images. We show the growth of the lava flow field associated with the explosive phase obtained from a fixed thermal monitoring camera. We estimate the erupted volume of pyroclasts from the heights of the lava fountains measured by the cameras, and the erupted lava flow volume from the satellite-derived radiant heat flux. We compare all erupted volumes (pyroclasts plus lava flows) with the total erupted volume inferred from the volcano deflation recorded by the borehole strainmeter, obtaining a total erupted volume of ~3 × 106 m3 of magma constrained by the strainmeter. This volume comprises ~1.6 × 106 m3 of pyroclasts erupted during the lava fountain and 2.4 × 106 m3 of lava flow, with ~30% of the erupted pyroclasts being remobilized as rootless lava to feed the lava flows. The episode lasted 130 min and resulted in an eruption rate of ~385 m3 s−1 and caused the formation of an ash plume rising from the margins of the lava fountain that rose up to 12.6 km a.s.l. in ~1 h. The maximum elevation of the ash plume was well constrained by an empirical formula that can be used for prompt hazard assessment.

The FastVRP automatic platform for the thermal monitoring of volcanic activity using VIIRS and SLSTR sensors: FastFRP to monitor volcanic radiative power

“…Results retrieved from VIIRS indicate that the 12 March 2021 paroxysms was the most intense in terms of radiative power, with values estimated around 17 GW (VIIRS image of 12 March 2021 at 10:48 UTC). This latter event was one of the most powerful and peculiar, because was accompanied by the formation of lava fountains which fed a very high eruptive column and an extensive ash plume [Calvari et al, 2021;. Marchese et al [2021] investigated the Mt.…”

Characterization of Volcanic Cloud Components Using Machine Learning Techniques and SEVIRI Infrared Images

“…Between 13 December 2020 and 21 February 2022, a new explosive phase took place at Mt. Etna, giving rise to 66 paroxysmal lava fountain episodes (from INGV weekly bulletins at , accessed on 1 July 2022) [ 53 , 54 , 55 ]. These events were characterized by Strombolian explosions, lava fountains, formation of short-lived lava flows and generation of eruptive columns [ 56 ].…”

The Transition from MODIS to VIIRS for Global Volcano Thermal Monitoring

“…The chosen volcanic targets (Table 4 and Figure 11) show thermal emissions ranging from about 1 MW to more than 1 GW and embed a variety of volcanic activity that includes: silicic lava domes (Shiveluch, Sabancaya, Nevados de Chillan), andesitic lava domes (Bagana), lava lakes (Nyiragongo), open vent (Etna, Manam), and mafic lava flow (Kilauea, Pacaya). Some of these volcanoes have experienced important eruptive phases in the considered period (see Supplementary Material), such as Etna [99,100], Nyiragongo volcano [101], and Kilauea [102]. However, in addition to their recent activity, these volcanoes have been chosen because they are representative of a wide range of environmental and meteorological conditions spanning from ice-covered high-latitude volcanoes (e.g., Sheveluch) to tropical islands (e.g., Bagana, Kilauea).…”