Identification of seismogenic nodes in the Alps and Dinarides

Seismogenic nodes - specific structures formed at the intersections of fault zones - have been identified in the Alps and Dinarides. The nodes have been delineated by the morphostructural Zoning (MZ) method and their seismic potential has been evaluated by the pattern-recognition method. With MZ we have compiled a morphostructural map (scale 1:1,000,000) for the study region. using the GIS technology. The map shows the hierarchical block-structure of the region, the network of boundary zones bounding blocks, and the loci of the nodes. A three-level hierarchy, has been established for the blocks and their boundaries. The recorded M greater than or equal to 6.0 earthquakes nucleate at the nodes delineated by MZ, i.e. ignoring the seismic record. Among all delineated nodes we recognized the seismogenic ones (D), prone to M greater than or equal to 6.0 earthquakes, with the pattern recognition aloorithin CORA-3. The majority of these nodes is associated with the first and second rank boundaries, i.e. larger earthquakes originate at the boundaries of larger blocks. We have identified a number of D nodes, where strong earthquakes have not yet been recorded. In the Alps, these nodes form spatial clusters in the French-Italian Alps, in the Northern Calcareous Alps, in the Dolomites, and in the Karawanken. In the Dinarides, such nodes occur on the Adriatic coast and form two small clusters in the South and in the east of Serbia. The nodes capable of M greater than or equal to 6.5 earthquakes are identified with the criteria of high seismicity nodes, previously derived from pattern recognition in the Pamirs-Tien Shan region. With these criteria we obtained satisfactory classification of the nodes for the Dinarides, while for the Alps the defined number of high seismic potential nodes is open to discussion.