We present a 1:10,000 scale map of the coseismic surface ruptures following the 26 December 2018 Mw 4.9 earthquake that struck the eastern flank of Mt. Etna volcano (southern Italy). Detailed rupture mapping is based on extensive field surveys in the epicentral region. Despite the small size of the event, we were able to document surface faulting for about 8 km along the trace of the NNW-trending active Fiandaca Fault, belonging to the Timpe tectonic system in the eastern flank of the volcano. The mapped ruptures are characterized in most cases by perceivable opening and by a dominant right-oblique sense of slip, with an average slip of about 0.09 m and a peak value of 0.35 m. It is also noteworthy that the ruptures vary significantly in their kinematic expression, denoting locally high degree of complexity of the surface faulting.

We provide a database of the surface ruptures produced by the 26 December 2018 Mw 4.9 earthquake that struck the eastern flank of Mt. Etna volcano in Sicily (southern Italy). Despite its relatively small magnitude, this shallow earthquake caused about 8 km of surface faulting, along the trace of the NNW-trending active Fiandaca Fault. Detailed field surveys have been performed in the epicentral area to map the ruptures and to characterize their kinematics. The surface ruptures show a dominant right-oblique sense of displacement with an average slip of about 0.09 m and a maximum value of 0.35 m. We have parsed and organized all observations in a concise database, with 932 homogeneous georeferenced records. The Fiandaca Fault is part of the complex active Timpe faults system affecting the eastern flank of Etna, and its seismic history indicates a prominent surface-faulting potential. Therefore, this database is essential for unravelling the seismotectonics of shallow earthquakes in volcanic areas, and contributes updating empirical scaling regressions that relate magnitude and extent of surface faulting.

In this paper we present a method for handling uncertainties in the determination of the source parameters of earthquakes from spectral data. We propose a robust framework for estimating earthquake source parameters and relative uncertainties, which are propagated down to the estimation of basic seismic parameters of interest such as the seismic moment, the moment magnitude, the source size and the static stress drop. In practice, we put together a Bayesian approach for model parameter estimation and a weighted statistical mixing of multiple solutions obtained from a network of instruments, providing an useful framework for extracting meaningful data from intrinsically uncertain datasets. The Bayesian approach used to estimate the source spectra parameters is a simple but powerful mechanism for nonlinear model fitting, providing also the opportunity to naturally propagate uncertainties and to assess the quality and uniqueness of the solution. Another important added value of such an approach is the possibility of integrating information from the expertise of seismologists. Such data can be encoded in a prior state of information that is then updated with the information provided by seismological data. The performance of the proposed approach is demonstrated analyzing data from the 23 April 1909 earthquake occurred near Benavente (Portugal).

On the night of 15–16 May 1951, two moderate earthquakes with estimated magnitudes of M_w 5.4 and 4.5 occurred in northern Italy, about 40 km southeast of Milan, close to the small town of Caviaga. They were recorded by several observatories worldwide, as reported by the International Seismological Summary (ISS) On‐Line Bulletin (ISS, 1951; International Seismological Centre [ISC], 2011). Despite the moderate magnitudes, these two events caught the attention of seismologists and have been studied in detail, in particular by Caloi et al. (1956), because they were close to Caviaga in an area that was...