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

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.