The eruption of Etna initiated on 30 May 2019: what is happening?

In the night of 29-30 May 2019, Mount Etna, in Sicily, Italy, erupted again. During the first eruptive phase, a dense column of ash was emitted from the New Southeast Crater; this activity ended in the afternoon of 30 May. Instead, a rather sustained Strombolian and effusive activity is continuing at the two fissures that opened in the north-east and south-east sectors of the New Southeast Crater (Nuovo Cratere di Sud Est). Images recorded by the surveillance IR cameras of the INGV and during field surveys by INGV staff show the expansion of two distinct lava flows within the Valle del Bove  (Figures 1 and 2).
20190531 Figura 1
Figura 1 – Top: Mean level of the volcanic tremor recorded at the ECPN (Cratere del Piano) seismic station, on the southwest side of the summit area. Below thermal (left) and high-definition (right) images recorded by the surveillance cameras of the INGV at Monte Cagliato, on the eastern flank of Etna, at the lower end of the Valle del Bove.
The northern lava flow extends toward the northern wall of the Valle del Bove and subsequently turns eastward, reaching a maximum distance of about 2 kilometers on the morning of May 31, at an estimated altitude of about 2050 meters. The second, southern lava flow is apparently more vigorously fed than the earlier, and emerges from a ground crack near the upper portion of the eruptive fissures that fed the eruption of December 2018. This flow expands towards the southeast along the western internal wall of the Valle del Bove, partially covering the lava flows of 2018. After skirting Serra Giannicola Piccola, in the early hours of 31 May the flow reached the bottom of the valley, with advancing lava fronts at about 1700 meters above sea level. Its estimated total length is about 3 kilometers.

20190531 aggiornamento Figura 2
Figura 2 – The eruptive scene at dawn on 31 May 2019, as recorded by the high-resolution surveillance camera installed at Monte Cagliato, on the eastern slope of Etna, at the lower end of the Valle del Bove.

The volcanic tremor amplitude, which suddenly increased in the first hours of the eruption, has progressively decreased since the afternoon of 30 May, remaining at medium-high values (Figure 1). The eruption was preceded by a few weeks of isolated seismic events with a maximum magnitude equal to Ml = 3.2 (27 April 2019, Pernicana fault, north-eastern flank of the volcano). On 29 May, a few hours before the start of the current eruption, a 
Ml = 2.8 earthquake occurred with its epicenter being located in the area of the village of Zafferana Etnea.

Article written by Boris Behncke, Marco Neri and Vincenza Maiolino, using the data obtained from the monitoring networks of the INGV.
Cover image: the eruptive theater on the night of May 30, 2019, taken from Santa Venerina village, on the eastern slope of Etna. Photo by B. Behncke.