The Earthquake Rotated Objects induced by the 2012 Emilia (Northern Italy) seismic sequence: relation with seismological and geomorphological factors

Abstract

In the past few years, the awareness that earthquake-induced rotational effects can be significant in the near-fault region of an earthquake, and the consequent implications in seismic engineering, has gained rotational seismology a strong recovery in the attention of the scientific community. Impulses came from direct observations as well as numerical simulations, and special volumes related to this topic have been recently published by the Bulletin of the Seismological Society of America (Lee et al., 2009) and by the Journal of Seismology (Igel et al., 2012). In particular, some of the most recent papers on this subject addressed the earthquake-rotated objects (EROs hereinafter), considering the possible contribution to EROs occurrence from true rotational motion and/or translational motion (Kozák, 2006, 2009; Yang et al., 2010; Hinzen, 2012), the geometry of the structure (Mucciarelli et al., 2011), the clockwise/ counterclockwise (CW/CCW hereinafter) sense of rotation (Yegian et al., 1994), and the geological conditions at the site (Cucci and Tertulliani, 2011; Castellano et al., 2012). The renewed attention to earthquake-induced rotations allowed the collection of a significant dataset of EROs following the Mw 6.3 2009 L’Aquila (Central Italy) event (see Cucci et al., 2011 for a complete description of the dataset); this kind of data collection is a sound starting point for subsequent quantitative analyses of the data. In this paper, we present a newⒺdataset of EROs (available in the electronic supplement to this paper) originated by the Emilia seismic sequence, which occurred in northern Italy in 2012. The main aim of this study is to verify whether and how the distribution of the 2012 EROs is influenced by some geophysical observables (epicentral distance, intensity, directivity, lithology, etc.), in a geomorphological and seismological context completely different from that of 2009 L’Aquila.