GNGTS 2018 - 37° Convegno Nazionale

GNGTS 2018 S essione 1.1 155 scenarios of an enigmatic area, such as the Hyblean Plateau. In the present work we correlated mapped geological structures with hypocentral locations and fault plane solutions of the 2016 sequence. In addition, synthetic simulations for the strongest event of the seismic sequence have been provided in order to produce the earthquake scenario relevant for the area. The geometry depicted by the seismicity hypocenters highlights a NS structure at about 8 km of depth. Accordingly, focal solutions indicate left-lateral movements on a fault-system trending about N185°E. Fault kinematics agrees with the roughly N-S oriented shear zone, known as Scicli-Ragusa Fault System (SRFS), lying few kilometers to the west and characterized by a bulk left-transtensive regime since the late Quaternary time. On average, synthetic data seem to describe well the observed PGAs and PGVs, at least at the stations of the RAN with soil class A and B considered here. This could suggest that they are supposed to be not affected by strong site effects. The major scatter between synthetic PGMs and observed ones seem to not depend on distance and/or azimuth and/or soil site. This suggests that the differences could account for the several factors that determine the intrinsic inter-event variability of PGM, such as source and path effects not completely modelled. References Boore D.M.; 2009: Comparing stochastic point- and finite-source ground-motion simulations: SMSIM and EXSIM . BSSA, 99 , 3203-3216. Gruppo Analisi Dati Sismici; 2018: Catalogo dei terremoti della Sicilia Orientale - Calabria Meridionale (1999- 2015), INGV-Catania. http://www.ct.ingv.it/ufs/analisti/catalogolist.php. Fig. 2 - (A) T90 vs epicentral distance for the earthquakes with 3.8 ≤ M L ≤ 4.8 recorded by the accelerometric stations within 50 km from the epicenter of the master event, used to derive the path duration model for the synthetic simulations. T90 values are from the Italian Accelerometric Archive (Luzi et al. , 2017). For comparison, the path duration model by Herrmann (1985) (DP=0.05R, where R is the distance). (B) and (C) Comparison between synthetic (little black dots) and observed (white and yellow circles) PGA and PGV values, respectively. Vertical bars stand for the interval between the minimum and maximum values of PGM obtained from each realization. (D) Shakemap computed using the synthetic PGAs obtained from stochastic simulation. Triangles represent the RAN stations.