Characteristics of the strong ground motions from the 6 April 2009 L’Aquila earthquake, Italy

Spectral-Element Simulations of Seismic Waves Generated by the 2009 L'Aquila Earthquake

“…In particular, the epicentral area corresponds to the upper and middle Aterno valley, with Quaternary lacustrine deposits forming its basins. The depth of the deposits in this area varies from about 60 m to more than 200 m from the upper to the middle Aterno valley (Bosi and Bertini, 1970), and much evidence of ground-motion amplification has been found (e.g., De Luca et al, 2005;Akinci et al, 2010). Finally, remarkable topographic ridges characterize the region, including the Gran Sasso and Maiella massifs to the east and the Simbruini Mountains to the west (e.g., Chiarabba et al, 2010;Fig.…”

“…The 2009 M w 6.3 L'Aquila mainshock was recorded by a dense network of receivers (e.g., Akinci et al, 2010;Chiarabba et al, 2010 Figure 1.…”

“…In fact, these time series provide onscale seismic signals recorded very close to the event, and, in other studies, they have been used to estimate, for example, source parameters, seismic attenuation, and local site amplification effects (e.g., Bindi et al, 2009;Akinci et al, 2010).…”

“…Moreover, these effects can be intensified and complicated by topographic ridges, which can cause amplifications, reflections, and multipathing (e.g., Lee et al, 2008;). Significant site amplifications have been observed for the 2009 M w 6.3 L'Aquila event in neighboring regions (e.g., Ameri et al, 2009;Bindi et al, 2009;Akinci et al, 2010;Çelebi et al, 2010). At L'Aquila city, for example, based on previous studies (e.g., De Luca et al, 2005), these effects are related to the presence of a basin filled with lacustrine sediments with a maximum depth of 250 m. Central Italy features several other sedimentary basins, and these can have a similar influence on ground motion (e.g., Bindi et al, 2004Bindi et al, , 2009Castro et al, 2004).…”

“…Imaging of the source (Anzidei et al, 2009;Atzori et al, 2009;Cirella et al, , 2012Pino and Di Luccio, 2009;Cheloni et al, 2010;Scognamiglio et al, 2010) highlights a complex rupture history composed of two main slip releases and controlled by spatial variations of material properties along the fault Lucente et al, 2010;Di Stefano, Chiarabba, et al, 2011) as well as temporal variations (Lucente et al, 2010;Zaccarelli et al, 2011). The source characteristics are partly responsible for the southeast directivity (Pino and Di Luccio, 2009;Akinci et al, 2010) and the unusually high levels of strong acceleration recorded close to L'Aquila city Çelebi et al, 2010). We note that all previous source imaging studies have adopted 1D layered seismic wavespeed models for the inversion, even excluding the topography which, however, is relevant in a region like Abruzzo that is crossed by the Apennines.…”