Morphostructural Zonation and Preliminary Recognition of Seismogenic Nodes Around the Adria Margin in Peninsular Italy and Sicily
The study is based on the assumption that strong earth-quakes are associated with the nodes that are specific structures formed around the intersections of the fault zones. The nodes have been delineated with the morphostructural zonation method, based on the idea that the lithosphere is made-up of different-scale blocks, separated by mobile boundaries. The morphostructural map, compiled with the GIS technology at the scale of 1:1,000,000, shows the hierarchical block-structure of the region, the network of boundary zones, the bounding blocks, and the loci of the nodes. The results of the morphostructural analysis indicate the very important role of the E-W trending fault zones in the present-day block-structure of the region around the Adria margin, peninsular Italy and Sicily, especially in the Apennines. The crustal earthquakes with M ≥ ۶٫۰ recorded in the region are nucleated at some of the mapped nodes. With the assumption that the future strong events will occur at the nodes, the seismic potential of each node has been evaluated for two magnitude thresholds, M ≥ ۶٫۰ and M ≥ ۶٫۵٫ The pattern recogni-tion algorithm “CORA-3” has been used in order to identify the nodes capable of earthquakes with M ≥ ۶٫۰ . Due to the few recorded quakes with M ≥ ۶٫۵ in the studied region, pattern recognition is not applicable to identify the nodes prone to quakes with M ≥ ۶٫۵٫ The nodes capable of such earthquakes have been identified by the criteria of high seismicity nodes, previously derived from pattern recognition in the Pamirs-Tien Shan region. The results obtained indicate a high seismic potential for the studied area and provide important information for seismic hazard assessment: a number of nodes where strong events have not been recorded to date, have been recognized to be prone to large earthquakes and they may warrant a detailed interdisciplinary investigation.