ASSESSMENT OF SEISMOACTIVE LAYERS IN ELBASANI GEOTERMAL ZONE, ALBANIA

Abstract

Albania is part of one of the most active seismic regions in Europe with dozens of devastating earthquakes throughout history. In this study, we will present an investigation of the earthquakes of the Elbasani region, in terms of the location accuracy and analysis of the features of the seismoactive layers. The distribution of focal depth shows the activation of a lithospheric zone, which extends in depth between 0 and 40 km. Accurate assessment of seismoactive layers of the Elbasani zone is of great interest in the recognition of the real depth of seismic energy generation and relations with low velocity layers. The depth of earthquakes has particular interest in the case of moderate and strong earthquakes because it is related to their effect on the surface. Strong earthquakes with shallow focal depth cause greater damage than earthquakes of the same magnitude but with a deeper focal depth. The b-value depth analysis is related to the stresses for the seismoactive layers. The crustal structure of the Elbasani zone with high b-values is likely to be associated with crustal low-velocity zones. The earthquakes are relatively smaller beneath the low-velocity zones where the high heat flow values are observed. The location of moderate earthquakes with depths from 20 to 35 km, which means less surface effect than the same earthquake with a depth smaller than 10km. The intensity in the epicenter is dependent by the magnitude and by the focal depth. Analysis of these earthquakes show that shocks with Ml > 4.5 have greater depths than earthquakes with smaller magnitudes. This analysis shows that the seismoactive layer in Elbasani zone lies at a depth of about 30 km. These results are a step towards more detailed geodynamic and seismotectonic analysis.