On December 26, 2018, a magnitude 4.9 earthquake occurred on the eastern flank of Mount Etna at a depth of less than 1 km. This event was the largest among those recorded during the intense seismic activity that began on December 23, 2018, and represents the most energetic event to have occurred on Mount Etna in the last 70 years. Earthquakes that occur in volcanic areas, such as Etna or Ischia, are very shallow and produce surface faulting even for low-magnitude earthquakes, as occurred with the earthquake of December 26, which produced significant surface faulting. In the days following the event, the emergency operations group of theIstituto Nazionale di Geofisica e Vulcanologia (INGV) EMERGEO, which deals with the survey of the coseismic effects on the natural environment (http://emergeo.ingv.it/), 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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