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S258 Int J Earth Sci (Geol Rundsch) (2010) 99 (Suppl 1):S243–S264

Fig. 4 Seismic potential of the Adriatic Basal Thrust (ABT), Sicilian MPS 2004b and DM w = 0.1 from Pace et al. 2006). The grey area
Basal Thrust (SBT) and Southern Tyrrhenian Compressional (STC) above the ABT1, SBT1 and STC1 slopes and the dotted areas above
seismotectonic province expressed as Gutenberg–Richter (G–R) the other G–R slopes (ABT2, ABT3, SBT2, SBT3, STC2, STC3)
slopes based on the earthquakes listed in Table 1, with exclusion of represent the uncertainty range owing to errors in event magnitude
the events from the interval of catalogue completeness. For each and completeness length of the catalogues, as calculated in this work.
province, three different G–R slopes were computed from the three The lower table reports the a value, b value and correlation coefficient
2
different completeness intervals given in Table 3 and different (R ) for the different computed G–R slopes
magnitude class subdivisions (DM w = 0.23 from Working group

The velocity tensor eigensystem calculated for the STC Discussion
seismotectonic province, assuming a rectangular parallel-
epiped shaped volume with a length of 260 km, surface In this paper, rates and azimuth of the seismic deformation
width of 50 km, an average depth of 20 km and computing which characterises the ABT province in the eastern
the moment tensor from the entire focal mechanism dataset Marche–Adriatic region, the SBT province in mainland-
in Table 2 indicate shortening at an average rate of southern Sicily and the STC province, off the northern
0.3 ± 0.1 mm/year along a N130°E direction. coast of Sicily have been obtained from seismic moment
For each province, the direction of the eigenvector summation of the seismic activity multiplied by the
associated with the highest absolute eigenvalue is projected moment tensor from available focal mechanisms and
in the map of Fig. 5 with a black arrow. divided by the inferred volume of the associated

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