FOCAL MECHANISMS AND TECTONIC SEISMOLOGICAL EVIDENCES IN THE PESARO AND URBINO PROVINCE

"Campus Scientifico" of the University of Urbino, Localita' Crocicchia - ex Sogesta, 61029, Urbino, Italy

GAS - Geological Assistance & Services - Pianoro Bologna (Italy)
Gruppo CSA - Centro Studi Ambientali - Rimini (Italy)

A focal mechanism study was carried out concerning seismic events occurred in the Pesaro and Urbino province from 1990 to 2002, using data recorded by the seismic network of the Istituto Nazionale di Geofisica e Vulcanologia. Analysis of these data showed that events can be considered in different sectors having similar seismological evidence. Focal mechanisms show that events belonging to the same sector have generally a well defined seismological evidence. In particular, it was possible to point out clearly an extensional stress regime in the axial sector and a compressional one in the sector from the high valley of the Marecchia river to the low valley of the Metauro river. The Adriatic off-shore sector shows not clear evidence of a nevertheless possible active compression; on the other hand no earthquake with magnitude greater than 5 occurred in the zone of northern Marche Adriatic off-shore in historical and recent times.

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