TITLE:
Present Tectonic Setting and Spatio-Temporal Distribution of Seismicity in the Apennine Belt
AUTHORS:
Enzo Mantovani, Marcello Viti, Daniele Babbucci, Caterina Tamburelli, Nicola Cenni, Massimo Baglione, Vittorio D’Intinosante
KEYWORDS:
Seismotectonics, Seismic Hazard, GPS, Apennines, Mediterranean
JOURNAL NAME:
International Journal of Geosciences,
Vol.6 No.4,
April
20,
2015
ABSTRACT: In previous papers, we
have argued that a close connection may exist between the discontinuous
northward displacement of the Adria plate and the spatio-temporal distribution
of major earthquakes in theperiAdriaticregions[1]-[3]. In particular, five seismic
sequences are tentatively recognized in the post 1400 A.D. seismic history,
each characterized by a progressive migration of major shocks along the eastern
(Hellenides, Dinarides), western (Apennines) and northern (Eastern Southern
Alps) boundaries of Adria. In this work, we describe an attempt at gaining
insights into the short-term evolution of the strain field that underlies the
migration of seismicity in the Apennine belt. The results of this study suggest
that seismicity in the study area is mainly conditioned by the fact that the
outer (Adriatic) sector of the Apennine belt, driven by the Adria plate, is
moving faster than the inner (Tyrrhenian) belt. This kinematics is consistent
with the observed Pleistocene deformation pattern and the velocity field
inferred by GPS data. The spatio-temporal distribution of major shocks during
the last still ongoing seismic sequence (post 1930) suggests that at present
the probability of next major shocks is highest in the Northern Apennines.
Within this area, we suggest that seismic hazard is higher in the zones located
around the outer sector of the Romagna-Marche-Umbria units (RMU), since that
wedge is undergoing an accelerated relative motion with respect to the inner
Apennine belt. This hypothesis may also account for the pattern of background
seismicity in the Northern Apennines. This last activity might indicate that
the Upper Tiber Valley fault system is the most resisted boundary sector of the
RMU mobile wedge, implying an higher probability of major earthquakes.