RECOGNITION OF EARTHQUAKE-PRONE AREAS. XVI\@. GENERAL CRITERIA OF MODERATE SEISMICITY IN FOUR REGIONS OF THE MEDITERRANEAN BELT ${\bf (M\geq 5.0)}$

A. I. Gorshkov, A. G. Tumarkin, M. B. Filimonov, and A. D. Gvishiani

Abstract

Four regions of the Mediterranean mobile belt are considered (the Caucasus, Western Apls, Pyrenees, and the Appennines together with Sicily) to determine general geomorphic criteria of locations where $M\geq 5.0$ earthquakes can occur. The regions are studied all together because of similarities in the present-day earth dynamics in them. The search for general criteria of seismicity was done using the Cora-3 algorithm on morphostructural zonation maps for the regions. It was found that $M\geq 5.0$ earthquakes tend to occur near intersections of active lineaments that separate homogeneous (in the geologic-geomorphic sense) crustal blocks identified by morphoistructural zonation. For this reason the patterns to be recognized were chosen to be vicinities of intersections of lineaments. The general criteria were determined using a set of geomorphic and morphostructural parameters that characterize lineament intersections in all the four regions. These parameters contain indirect indications of the intensity and gradient of tectonic movements and of the degree of crustal fragmentation. The learning material for the recognition algorithm included patterns from all the four regions. Recognition resulted in determining typical features of the $M\geq 5.0$ event-prone intersections that are common to all the regions (seismicity criteria). According to the features obtained, the earthquake-prone lineament intersections are characterized by high gradients of neotectonic movements and increased crustal fragmentation. The criteria can be used to identify earthquake-prone locations elsewhere within the Mediterranean-Himalayan mobile belt.

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Computational Seismology, Vol. 1.