Ground motion characteristics of the 2016 central Italy earthquake sequence

The 2016 Central Italy earthquake sequence occurred between August and November 2016. During the sequence, three mainshock events were well recorded by networks operated by the Italian Institute of Geophysics and Volcanology (INGV) and the Italian Department of Civil protection (DPC): (1) 24 August 2016 (M6.1), (2) 26 October 2016 (M5.9), and (3) 30 October 2016 (M6.5). These events occurred on normal faults roughly trending southeast-northwest. Each mainshock event has been followed by many aftershocks. We have analyzed recorded ground motions and supporting metadata for the three mainshocks and three of the principal aftershock events. Processing is performed on a component-by-component basis and the usable frequency range is identified. We take the seismic moment, moment magnitude, and moment tensor from an INGV catalogue. Finite fault dimensions, strike, and dip are assigned to each mainshock event. We compare ground motion intensity measures to local and global ground motion models, which shows several interesting features, including (1) fast distance attenuation for high frequency intensity measures at distances > 100 km; (2) over-prediction of ground motion by global models at short periods; and (3) a general under-prediction of ground motions at close distances. Effects 1 and 2 were also observed from the 2009 L'Aquila earthquake data, and may represent regional features. We analyze the spatial distribution of ground motions for the three mainshock events by means of a Kriging analysis performed on within-event peak ground acceleration residuals.