Clues for a relation between rotational effects induced by the Mw6.3 2009 L’Aquila (Central Italy) earthquake and site and source effects

摘要

The Mw6.3 2009 L’Aquila earthquake produced an impressivenumber of rotational effects on vertically organized objects such aschimneys, pillars, capitals and gravestones. We present the datasetof such effects, that consists of 105 observations at 37 different sitesand represents a compendium of earthquake-induced istances ofrotational effects that is unprecedented in recent times. We find thatthe absolute majority of the reported effects was observed in theepicentral zone and that most of the observations are located wherethe MCS intensity is between 7 and 8-9. The evident asymmetry inthe distribution of the rotational effects resembles the southeastwarddirectivity of the macroseismic effects and highlights asignificant convergence between rotations and damage. Finally, weperform some qualitative analyses to recognize and evaluate which*ManuscriptClick here to download Manuscript: revised_text.doc2geological and seismological parameters can be significantcontributors to local rotations. We find that surface geology andamplification of the seismic motion at each reported location stronglyinfluence the occurrence and the nature of the earthquake-inducedrotational effects. Conversely, the contribution of the pattern of slipdistribution on the fault plane plays only a secondary role inenhancing the rotational motion at each site.