The Caucasus Territory Hot-Cold Spots Determination and Description Using 2D Surface Waves Tomography

Abstract

Many questions have been raised about the thermal-mechanical development of plate tectonics boundary interactions, lithospheric processes, mantle activity, movement of faults, continental thinning, and generally the heat beneath our feet. The earthquake waves are originating in the Earth’s crust or upper mantle, which ricochet around the earth's interior and traveling most rapidly through cold, dense regions, and more slowly through hotter rocks. In this paper, in order to identify and describe the Caucasus territory Hot-Cold spots and better understand the regional tectonic activities based on the fast and slow wave velocity anomalies, the 2D tomographic maps of Rayleigh wave dispersion curves were imaged. To obtain these maps in the ever-evolving collision zone of the Eurasian-Arabic plates, we performed a 2D-linear inversion procedure on the Rayleigh wave in a period ranging from 5 to 70 s (depth ~200 km). To conduct this, ~1500 local-regional earthquakes (M≥3.7) recorded by the 48 broadband-short period stations from 1999 to 2018 were used. In this study, we assumed that the low-velocity tomography images or dark red-orange shades indicate hot spots (slow-regions) and high-velocity or dark blue-green-yellow shades imply cold spots (fast-regions). Therefore, by using the technique of increasing-decreasing the velocity anomaly in a wide area with complicated tectonic units the hot-zones and extensive cold-aseismic areas were described and investigated. Hence, for short-periods (5≤T≤25 s; 6.6≤depth≤30.8 km) 15 hot spots were determined. The result for medium-periods (30≤T≤45 s) show two hot spots with a depth of ~108 km. In long-periods (depth ~200 km), most part of the study area has covered by ultra-low-velocity anomaly as a permanent hot spots.