On December 26, 2018, an earthquake measuring Mw 4.9 occurred located on the eastern flank of Etna at a depth of less than 1 km. This event is the main one among those located during the intense Etna seismic activity that began on 23 December 2018 and represents the most energetic event that occurred on Etna in the last 70 years. The earthquakes that occur in volcanic areas, such as Etna or Ischia, being very superficial, produce superficial faulting even for low magnitude values, as in fact happened for the one of 26 December which produced significant superficial faulting. In the days following the event, the emergency operational group of the National Institute of Geophysics and Volcanology (INGV) EMERGEO, which deals with the relief of cosismic effects on the natural environment (), has taken steps to acquire geological data on the ground in the epicentral area. Nearly 900 observation points along the fault line have been collected and catalogued. For each point, in addition to the photographic documentation, the geometric and kinematic characteristics of the break were measured. Aerial shots were also taken with a drone for the photogrammetric reconstruction of the deformation scenario. The observations showed that the earthquake of 26 December produced the rupture of the Fiandaca fault with superficial faulting for about 8 km, from Acicatena up to Monte Ilice, also with the mobilization of some minor adjacent structures.
Image 1 - Detail of the active faults in the lower south-eastern flank of Etna (from Azzaro et al., 2012). The area in which the geological survey carried out by EMERGEO from 26/12/2018 to 18/01/2019 highlighted surface faulting is highlighted in purple. The yellow star represents the epicenter of the earthquake.
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