Lower Adriatic Sea seismic sequence (January 1986): spatial definition of the seismogenic structure

Abstract

In January 1986 a swarm-like seismic sequence (main shock M L = 4.8) took place in the lower Adriatic Sea. This sequence was recorded by the Italian Telemetered Seismological Network using a digital acquisition system. Using additional data collected by other Italian, Yugoslavian and Albanian institutions, 15 shocks of the sequence were located by means of the “master event” technique, and for two of them a focal mechanism solution was obtained. We attempted to frame our results within the knowledge available in the literature. The Adriatic microplate is regarded by many authors as a whole block; nevertheless it exhibits moderate seismicity. The question has arisen as to whether it can be considered an African promontory or whether it behaves independently. The area actived by the sequence is rather small (less than 10 km in diameter) owing to the low level of seismic energy release and does not show any particular trends. The focal mechanisms are consistent with the recent stress field in the Adriatic area inferred from previous studies, which indicate a compression axis oriented NE-SW.