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220 G. LAVECCHIA ET ALII

7. CONCLUSIONS BARATTA M. (1897) - Materiali per un catalogo dei fenomeni sismici
avvenuti in Italia (1800-1872). Mem. Soc. Geog. It., 7, 81-164.
Taking into account data from the previous literature BARCHI M.R., DE FEYTER A., MAGNANI M.B., MINELLI G., PIALLI G.
and the seismological evidence discussed here, we feel & SOTERA B.M. (1998) - The structural style of the Umbria-Mar-
confident enough to state that the ABT and SBT are che fold and thrust belt. Mem. Soc. Geol. It., 52, 557-578.
active segments of the outer front of the Apennine- BELLO M., FRANCHINO A. & MERLINI S. (2000) - Structural model of
Eastern Sicily. Mem. Soc. Geol. It., 55, 61-70.
Maghrebian fold-and-thrust belt system. They are both
BEN AVRAHAM Z., BOCCALETTI M., CELLO G., GRASSO M., LENTINI
first-order crustal-scale seismogenic structures which F., TORELLI L. & TORTORICI L. (1990) - Principali domini strut-
strongly control reverse, reverse-oblique and strike-slip turali originatisi dalla collisione Neogenico-Quaternaria nel Medi-
seismic activity. Relatively deep (10-to-30 km) seismicity terraneo. Mem. Soc. Geol. It., 45, 453-462.
occurring in the pede-Apennine region and in mainland BOLLETTINO MACROSISMICO - Istituto Nazionale di Geofisica, Roma.
Sicily may be associated with brittle shearing of the mid- http://www.ingv.it/~roma/attivita/pererischio/macrosismica/macros/
dle and lower crust thrusts segments, whereas the shal- bollettino/elenco.html.
low seismicity (<~10 km) close to the ABT and SBT sur- BOLLETTINO SISMICO ITALIANO. http://www.ingv.it/~roma/reti/rms/
bollettino/
face tip line is associated with reverse, oblique and BONCIO P., LAVECCHIA G. & PACE B. (2004) - Defining a model of 3D
strike-slip shearing of the two upper crust thrust seg- seismogenic sources for Seismic Hazard Assessment applications:
ments and of their frontal and lateral splays. The case of central Apennines (Italy). Journal of Seismology, 8,
Although there is knowledge of a significant number 407-425.
of moderate to relatively large earthquakes which struck BOSCHI E., GUIDOBONI E., FERRARI G., GASPERINI P., MARIOTTI
both the ABT and SBT seismogenic compressional D. & VALENSISE G. (2000) - Catalogo dei forti terremoti in Ita-
provinces (42 events with 4.5≤M aw ~6.0 in Sicily and 76 in lia dal 461 a.C. al 1997. Annali di Geofisica, 43, 843-868 and
the Adriatic within the completeness interval), the seismic CD-ROM.
BOUSQUET J.C. & LANZAFAME G. (1986) - Deformations compressives
hazard of Sicily is commonly underestimated (WORKING quaternaires au bord sud de l’Etna. C.R. Acad. Sc. Paris, 303,
GROUP MPS, 2004 and references therein). In this paper, 235-240.
we point out not only a close geometric and seismotec- BUTLER R.W.H., GRASSO M. & LA MANNA F. (1992) - Origin and
tonic similarity between the ABT and SBT (figs. 2 and 5), deformation of the Neogene-Recent Maghrebian foredeep at the
but also an impressive, and up to now unnoticed, equiva- Gela Nappe, SE Sicily. Journal of Geological Society of London,
lence between the yearly energetic release per unit area of 149, 547-556.
the «Pede-Apennine Province» and of the «Mainland CACCAMO D., NERI G., SARAO A. & WYSS M. (1996) - Estimates of
Sicily Province» (tab. 3). The highlighted differences in stress directions by inversion of earthquake fault plane solutions
seismic activity between the «Coastal-Adriatic Province» in Sicily. Geophys. J. Int., 125, 857-868.
and the «Southern Sicily Province» also appears CALAMITA F., CELLO G., CENTAMORE E., DEIANA G., MICARELLI A.,
PALTRINIERI W. & RIDOLFI M. (1991) - Stile deformativo e crono-
extremely intriguing, as they are similar in terms of active logia della deformazione lungo tre sezioni bilanciate dall’appenni-
tectonics and seismogenic sources. This difference may no Umbro-Marchigiano alla costa Adriatica. Studi Geologici Ca-
be ascribed to a more ductile mechanical behaviour of merti, Vol. speciale 1991/1, 295-314.
the shallow SBT, under different rheological constraints, CALAMITA F., COLTORTI M., PIERUCCINI P. & PIZZI A. (1999) - Evolu-
and/or to longer recurrence time intervals. Our research zione strutturale e morfogenesi plio-quaternaria dell’Appennino
certainly needs further development, but we hope it will umbro-marchigiano tra il preappennino umbro e la costa adriati-
ca. Boll. Soc. Geol. It., 118, 125-139.
help to stimulate a revaluation of the seismic potential of CALAMITA F., SCISCIANI V., MONTEFALCONE R., PALTRINIERI W. &
Sicily in terms of seismic hazard assessments. PIZZI A. (2002) - L’ereditarietà del paleomargine dell’Adria nella
geometria del sistema orogenico centro-appenninico: l’area abruz-
zese esterna. Mem. Soc. Geol. It., 57, 355- 368.
ACKNOWLEDGEMENTS
CALAMITA F., VIANDANTE M.G. & HEGARTY K. (2004) - Pliocene-Qua-
We wish to acknowledge Laura Peruzza and Marco Menichetti ternary burial/exhumation paths of the Central Apennines (Italy):
for constructive comments on the manuscript and Pierpaolo Guar- implications for the definition of the deep structure of the belt.
nieri for accompanying us to visit some Sicilian active folds. Many Boll. Soc. Geol. It., 123, 503-512.
thanks to Bruno Pace and Paolo Boncio for daily discussion on the CARBONE S., CATALANO S., DI STEFANO A., GUARNIERI P. & LENTINI
topics. F. (2000) - Evoluzione tettonica della Sicilia orientale. In: Le ricer-
che del GNDT nel campo della pericolosità sismica (1996-99). F.
Galadini, C. Meletti, A. Rebez (Eds.). CNR-Gruppo Nazionale
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