EARTHQUAKE RUPTURE ON THE FIANDACA FAULT, DEC. 26, 2018, MW 4.9: FAULT FABRIC ANALYSIS, INTENSITY VS. SURFACE FAULTING, AND HISTORICAL SEISMICITY AT MT. ETNA VOLCANO, ITALY

Abstract

On December 26, 2018, a Mw 4.9 earthquake hits the eastern flank of Mount Etna volcano (Sicily). The epicenter is located between the Fleri and Pennisi villages, and focal depth is estimated at 0.3 km (http://cnt.rm.ingv.it/event/21285011). This earthquake is part of a seismic sequence begun on December 23, 2018 and a concurrent phase of volcanic eruption, eventually resulting in lava flows and a dyke intrusion (De Novellis et al., 2019).The earthquake is the result of the activation of the Fiandaca Fault; it is accompanied by widespread surface faulting and secondary environmental effects (Emergeo Working Group, 2019; Figs. 1 - 3), and have a maximum intensity of VIII EMS (Quest WG, 2019).Partial or complete ruptures of the Fiandaca Fault are well-documented in the last 150 years (Fig. 1). The last event that activated the entire structure, as happened in 2018, occurred in 1894 and generated extensive surface faulting and secondary effects (Riccò, 1894; Baratta, 1894; Imbò, 1935).Despite the abundant documentation of previous events, the Fleri earthquake represents the first opportunity to document coseismic effects of a strong, shallow seismic event at Mt. Etna through modern field techniques, sustained by accurate remote-sensed data, including unprecedented InSar measurements.