The seismotectonics of the Po Plain (northern Italy): tectonic diversity in a blind faulting domain

We present a systematic and updated overview of a seismotectonic model for the Po
Plain (northern Italy). This flat and apparently quiet tectonic domain is in fact rather
active as it comprises the shortened foreland and foredeep of both the Southern Alps
and the Northern Apennines. Assessing its seismic hazard is crucial due to the
concentration of population, industrial activities and critical infrastructures, but it is also
complicated because a) the region is geologically very diverse, and b) nearly all
potential seismogenic faults are buried beneath a thick blanket of Pliocene-Pleistocene
sediments, and hence can be investigated only indirectly.
Identifying and parameterizing the potential seismogenic faults of the Po Plain requires
proper consideration of their depth, geometry, kinematics, earthquake potential and
location with respect to the two confronting orogens. To this end we subdivided them
into four main homogeneous groups. Over the past 15 years we developed new
strategies for coping with this diversity, resorting to different data and modeling
approaches as required by each individual fault group.
The most significant faults occur beneath the thrust fronts of the Ferrara-Romagna and
Emilia arcs, which correspond to the most advanced and buried portions of the
Northern Apennines and were the locus of the destructive May 2012 earthquake
sequence. The largest known Po Plain earthquake, however, occurred on an elusive
reactivated fault cutting the Alpine foreland south of Verona. Significant earthquakes
are expected to be generated also by a set of transverse structures segmenting the
thrust system, and by the deeper ramps of the Apennines thrusts.
The new dataset is intended to be included in the next version of the Database of
Seismogenic Sources (DISS; http://diss.rm.ingv.it/diss/, version 3.2.0, developed and
maintained by INGV) to improve completeness of potential sources for seismic hazard
assessment.