REGULARITIES IN TIME AND SPACE DISTRIBUTION OF SEISMICITY IN THE PERIADRIATIC REGIONS - TECTONIC IMPLICATIONS

The pattern of energy release in the very active seismic belt along the Hellenides and southern Dinarides, which is interpreted as the main collison boundary between the Adriatic plate and the Balkan regions, has been characterized in the last three centuries by a fairly regular succession of active and quiescent phases. Statistical tests have indicated a very low probability of observing this kind of pattern associated with a random generation of earthquakes. The discontinuous release of seismic energy might be connected with a periodic activation of the underthrusting of the Adriatic Mesozoic platform beneath the Dinarides-Hellenides belts. This effect could condition the kinematic behavior of the whole Adriatic plate. This hypothesis might explain the fact that the Italian regions, lying on the other side of the Adriatic platform, also show a seismic energy release pattern characterized by alternating active and quiescent periods, which, furthermore, proves to be well correlated in time with those occurring at the Adriatic-Balkan border.