GNGTS 2022 - Atti del 40° Convegno Nazionale

GNGTS 2022 Sessione 1.1 27 ACTIVE TECTONICS AND FAULT EVOLUTION IN THE WESTERN BALKANS N. D’Agostino 1 , A. Copley 2 , J. Jackson 2 , R. Koci 3 , A. Hajrullai 3 , L. Duni 3 , N. Kuka 3 1 Osservatorio Nazionale Terremoti, Istituto Nazionale Geofisica e Vulcanologia, Roma, Italy 2 Bullard Laboratories, University of Cambridge, UK 3 Department of Seismology, Institute of Geosciences, Energy, Water and Environment, Tirana, Albania The western Balkans occupy a region influenced by two major active tectonic processes: the collision between the Adriatic Sea and the Dinarides in the west and the extension of the Aegean Sea and its surroundings as they move towards the Hellenic Trench. An understanding of the kinematics and dynamics of the western Balkans has significance for our understanding of continental tectonics in general. The region is rich in observational data, with many well- studied earthquakes, good geodetic coverage by GNSS, and abundant exposure of active faulting and its associated geomorphology, especially within the Mesozoic carbonates that cover much of the extensional areas. We first use such observations to establish the regional kinematic patterns, by which we mean a clarification of how active faulting achieves the motions observed in the deforming velocity field obtained from GNSS measurements. We then use observations from geomorphology and the evolution of drainage systems to establish how those kinematic and faulting patterns have changed and migrated during the Late Neogene-Quaternary. The kinematics, and its evolution, can then be used to infer characteristics of the dynamics, by which we mean the origin and effect of the forces that control the overall deformation. The principal influences are: (a) the distribution and evolution of gravitational potential energy (GPE) contrasts arising from crustal thickness variations and elevation, in particular the growth of topography by shortening in the Albanides-Hellenides mountain ranges and the high elevation of mainland Greece relative to the Mediterranean sea floor; (b) the ability of the boundaries of the region, along the Adriatic coast and in the Hellenic Trench, to support the forces arising from those GPE contrasts. The evolution in space and time indicates an interaction between the anisotropic strength fabric of the upper crust associated with faulting, and the more distributed and smoother patterns of flow that are likely to characterise the ductile deformation of the lower, aseismic part of the lithosphere --- both of which influence the deformation on the scale of 100—200~km.