Ormeni, Rrapo; Hasimi, Albana; Öztürk, Serkan; Çomo, Ervin

In this study, the correlations between the heat flow density and seismotectonic b-value in the El-basani area of Albania were investigated to understand the how low-velocity layers underneath the Elbasani area in central Albania struggling the large-scale Vlora-Lushnja-Elbasani-Dibra Fault Zone affect the heat flow data. For this purpose, the heat flow and regional distribution of b-value were imaged for different locations and depths. To achieve the analysis, the Albanian Seismological Catalogue for the period between 1 July 1968 and 26 December 2022, including 1830 earthquakes with a local magnitude of 0.5 ≤ Ml ≤ 5.2 that occurred at the depths below 70 kilometres, was considered. The b-value was calculated as 1.03 ± 0.06 by considering the magnitude of the completeness value as Mc-value = 2.6. This result shows that the b-value of earthquake distribution in the Vlora-Lushnja-Elbasani-Dibra (VLED) fault zone is well represented by the Gutenberg and Richter (G-R) scaling law with the b-value close to 1.0. The regional variations of the b-value show that b-values smaller than 0.9 were observed in the western and south-western parts of the Llinxha-Kozan thermal water belt. The depth distribution of the b-value indicates that there exists a sharp decrease in the b-values from 1.15 to 0.7 in the depths varying from 5 to 20 km. The highest heat flow values were observed on the Dumrea diapiric dome and in the central part of the Elbasani area. Thus, our analysis indicates significant and robust correlations between the geothermal and earthquake distribution. The discontinuity of Moho interface is deep in the regions where high b-values were observed. Low b-values are found at the depths ranging from 20–25 km and 35–40 km in the Dumrea evaporite massif area. We have evidence that high b-values and large heat flow values are related to the low seismic velocity layers underneath the Elbasani area. The low-velocity zone (LVZ) in Albania occurs in the Earth’s crust and in the upper mantle. It is characterized by an unusu-ally low seismic shear wave velocity compared to the surrounding depth intervals. It is well known that the low-velocity layers in the Elbasani area are determined in the upper crust, at shallow depths of 2–4 km, and in the middle crust at a 10–14 km depth. Hence, it is suggested that the Moho interface in the eastern part of the Elbasani area is relatively deep (45 km) compared to the western part of Albania (35 km), and the magnitude of earthquakes is smaller where the high heat flow values were observed.

Ormeni, Rrapo; Öztürk, Serkan; Hasimi, Albana; Silo, Erald; Como, Elvin; Trofymchuk, O.; Rivza, B.

A detailed analysis of the b-value within the Elbasani fault zone, Albania, were studied. From instrumental seismicity in this area have been located 1830 seismic events, with magnitude Ml>0.5 Richter. In the zone of Elbasani, hot mineral water (thermal waters) spot out from natural springs which have been known since the 19th century. The statistical properties of seismicity are analysed by using b-value known as Gutenberg-Richter law. The magnitude of completeness (Mc) value is determined as 2.6, and the bvalue is calculated as 1.03 ± 0.06, and it is determined that the region has a normal stress level. It is seen that the Mc-value varies from 1.6 to 2.9, the b-value changes between 0.9 and 1.3. The regions with the large b-values (> 1.0) are estimated in the eastern parts of the of Elbasani zone. However, the regions with the low b-values (< 1.0) are observed in the north, west and southwest of Elbasani zone. The regions with the small b-values correspond to great-magnitude events, whereas the other large values are related to smallmagnitude earthquakes. These results reveal that b-values for all regions are well represented by a b-value typically close to 1.0. There are clear decreasing trends in temporal changes of b-values before the occurrences of some strong main shocks. The lower b-value indicate that there is still moderate stress accumulation in the southwest area of the Llinxha-Kozan thermal water belt. The b-values smaller than 1.0 indicate potential future earthquake area. Following the strong events, there are remarkable decreases in b-value as a function of time. Changes in b-value with time varies in a large band between 0.6 and 1.4. Probabilities of earthquake activity in different magnitude sizes show comparatively great values changing from 50-100 % for earthquakes of 0.5 ≤ Ml≤ 4.5 and the values relatively lower than 90 % for the earthquakes of 5.0 ≤ Ml. The Elbasani zone has a complex geological structure with a significant number of geothermal water resources and some features of seismicity.