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S262 Int J Earth Sci (Geol Rundsch) (2010) 99 (Suppl 1):S243–S264

active compression (eastern Marche–Adriatic region, among the ABT, the SBT and the STC indicate comparable
mainland-southern Sicily and northern Sicily offshore) seismogenic potential to ongoing compression along the
(Figs. 1, 3). The surface and depth geometry of the Apennine–Maghrebian thrust front, with evident implica-
seismogenic volumes involved in the deformations were tions in terms of seismic hazard implications.
assumed from previous papers (Lavecchia et al. 2007a, b),
where they had been constrained from integrated geologi-
cal–seismological data.
The errors involved in the evaluation of the crustal References
deformation using seismicity catalogue may be significant,
owing to the possible restrictions on the validity of the Aki K, Richards P (1980) Quantitative seismology. Theory and
methods. Freeman, San Francisco
adopted formulas, as well as to the uncertainties of the used
Anderson H, Jackson J (1987) Active tectonics of the Adriatic region.
parameters, that include not only the completeness and Geophys J R Astron Soc 91:937–983
quality of the seismological record, but also the adopted Azzaro R, Barbano MS (2000) Analysis of seismicity of southeastern
geometry of the seismotectonic source. The standard Sicily: proposal of a tectonic interpretation. Ann Geofis 43:171–
188
deviations associated with our solutions were evaluated
Azzaro R, Barbano MS, Camassi R, D’Amico S, Mostaccio A,
following the approach described in Papazachos and Piangiamore G, Scarfı ` L (2004) The earthquake of 6 September
Kiratzi (1992), which allows the determination of the range 2002 and the seismic history of Palermo (Northern Sicily, Italy):
of fluctuations of the results, considering all the possible implications for the seismic hazard assessment of the city. J of
Seismol 8:525–543
random errors of the model parameters by means of a
Baratta M (1897) Materiali per un catalogo dei fenomeni sismici
generator of Gaussian noise type. The seismic strain rate avvenuti in Italia (1800–1872). Mem Soc Geogr Ital 7:81–164

tensor _ e ij and the velocity tensor (U ij ) components were Barba S, Basili R, Carafa MMC (2007) Finite element modeling-
computed for the ABT, SBT and STC seismotectonic derived slip rates of seismogenic sources (http://diss.rm.
ingv.it/fem/S2_D3.8.html), deliverable D3.8 of Project S2
provinces, with the eigenvalues measured in mm/year and
‘‘Valutazione del potenziale sismogenetico e probabilita ` dei forti
the direction angles of the eigenvectors expressed as trend terremoti in Italia’’ INGV/DPC http://www.ingv.it/progettiSV/
and plunge (table within Fig. 5). In the map of Fig. 5, the Progetti/Sismologici/sismologici_con_frame.htm
direction of the eigenvector associated with the highest Barbano MS, Bottari A, Careni P, Casentino M, Federico B, Fonte G,
Lo Giudice E, Lombardo G, Patane ` G (1979) Macroseismic
absolute eigenvalue (k1) of each province is projected and
study of the Gulf of Patti earthquake in the geostructural frame
the coordinates of the vertex of the polygons, which of north-eastern Sicily. Boll Soc Geol Ital 98:155–174 http://
schematise the surface geometry of each province, are www.ingv.it/progettiSV/Progetti/Sismologici/sismologici_con_
given. The level of seismic activity in terms of seismic frame.htm
Barchi MR, De Feyter A, Magnani MB, Minelli G, Pialli G, Sotera
potential, expressed as G–R slope, has also been computed
BM (1998) The structural style of the Umbria-Marche fold and
for the three provinces (Fig. 4), which are almost equal in thrust belt. Mem Soc Geol Ital 52:557–578
terms of their mean b values (1.1–1.2) and moderately Basili R, Barba S (2007) Migration and shortening rates in the
different in terms of their average a values (4.5–4.8). Northern Apennines, Italy: implications for seismic hazard.
Terra Nova 19:462–468
In all three analysed provinces, the strain tensor is of the
Billi A, Presti D, Faccenna C, Neri G, Orecchio B (2007)
reverse-type, with a prevailing sub-horizontal contractional Seismotectonics of the Nubia plate compressive margin in the
component (k 1 ) and with shortening rates of 0.3–0.4 mm/ south Tyrrhenian region, Italy: clues for subduction inception.
year in a nearly WSW–ENE direction across the ABT J Geophys Res 112:B08302. doi:10.1029/2006jb004837
Boncio P, Bracone V (2008) Active stress from earthquake focal
province, of 0.1–0.2 mm/year in a nearly N–S direction
mechanisms along the Padan Adriatic side of the Northern
across the SBT province and of 0.3–0.4 mm/year in the Apennines (Italy), with considerations on stress magnitudes and
NW–SE direction across the STC province, respectively. pore-fluid pressure. Tectonophysics 299:195–210
These evaluated compressional seismic releases are modest, Boschi E, Guidoboni E, Ferrari G, Gasperini P, Mariotti D, Valensise
G (2000) Catalogo dei forti terremoti in Italia dal 461 a.C. al
but tectonically controlled and not strongly different in the
1997. Ann Geofis 43:843–868
three regions. This is an interesting result, as in the recent Caccamo D, Neri G, Sarao A, Wyss M (1996) Estimates of stress
literature a growing importance in active tectonic terms has directions by inversion of earthquake fault plane solutions in
been attributed to the STC belt, where most of the recent Sicily. Geophys J Int 125:857–868
Castello B, Selvaggi G, Chiarabba C, Amato A (2005) CSI Catalogo
Africa–Nubia convergence would be accommodated (Goes
della sismicita ` italiana 1981–2002. http://www.ingv.it/CSI/
et al. 2004; Montone et al. 2004; Pondrelli et al. 2004; Neri Catalano S, Torrisi S, De Guidi G, Grasso G, Lanzafame G,
et al. 2005; Billi et al. 2007). Conversely, the seismicity of Romagnoli G, Tortorici G, Tortorici L (2007) Sistema a pieghe
the eastern Marche–Adriatic region, and especially that of tardo- quaternarie nell’area di Catania: un esempio di fronte
orogenico attivo. Rend Soc Geol Ital 4:181–183
the mainland-southern Sicily region, has been underesti-
Chiarabba C, Jovane L, DiStefano R (2005) A new view of Italian
mated (Kiratzi 1994; Pondrelli et al. 1995; Jenny et al. 2006; seismicity using 20 years of instrumental recordings. Tectono-
Billi et al. 2007). Conversely, similar velocity tensors physics 395:251–268

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