Spatial and temporal analysis of recent seismicity in different parts of the Vlora-Lushnja-Elbasani-Dibra Transversal Fault Zone, Albania

Abstract

Spatial and temporal evaluation of current seismic activity throughout the Vlora-Lushnja-Elbasani-Dibra (VLED) transversal fault zone were carried out at the beginning of year 2016. The seismotectonic b-value, fractal dimension Dc-value and precursory seismic quiescence Z-value are considered for a detailed statistical analysis. Completeness magnitude Mc-value varies from 2.5 to 2.7 for different parts of the VLED fault zone. The b-value is calculated as 1.10±0.04 for the south western part and 1.13±0.05 for the middle part, whereas it is estimated as 0.94±0.07 for the north eastern part of the study region. 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. On the contrary, no earthquakes are observed in some periods after decrease of b-value. Dc-values are computed as 2.66±0.04 for the south western part, 2.64±0.03 for the middle part and 2.15±0.02 for the north eastern part of the VLED fault zone. These rather large values show that earthquake activity is more clustered at larger scales or in smaller areas in the study area.Considering the phenomenon of seismic quiescence as a precursor of the main earthquakes gives successful outcomes in defining the potential anomalies and possible locations of future earthquakes. Quiescence analysis of current seismicity at the beginning of 2016 in the VLED fault zone is performed with the test of standard normal deviate Z-value. Distributions of resulting Z-values show six anomalous regions along the different parts of the VLED fault zone. These quiescence areas are detected at (i) 40.81ºN-19.86ºE (including Kuc-Bubullim, southeast of Lushnja town), (ii) 41.00ºN-20.01ºE (in the Cerriku, south of Elbasani town), (iii) 41.31ºN-20.13ºE (around Bene-Qafe, northeast of Elbasani town), (iv) 41.43ºN-20.21ºE (Krasta-Batra, south of Bulqiza town), (v) 41.28ºN-20.49ºE (including Carrishta-Stebleve, northeast of Librazhdi town), (vi) 41.51ºN-20.51ºE (including Qerrenec-Gjorica, west of Dibra town). As an important result, analyses of spatial and temporal characteristics of the earthquake activity may supply significant clues for revealing the future seismic hazard along the VLED fault zone, and these anomaly regions may be interpreted as the locations of next possible earthquakes.

Statistics of the earthquakes in the central Himalaya and its vicinity in last 56 years, with an emphasis in the 25 April 2015 Gorkha, Nepal earthquake

“…The Grassberger and Procaccia (1983) correlation dimension calculation method or sphere counting method is among the extensively used method to study space time characteristics of earthquake activity. It is based on power law and is used for spatio-temporal studies on the space-time characteristics of earthquake activity for various parts of the world (Oncel and Wilson, 2007;Ormeni et al, 2017;Pailoplee and Choowong, 2014;Roy et al, 2011). In this method the correlation integral function is defined as:…”

Analysis of Seismicity in Elbasani Geothermal Zone during Five Last Decades

“…The Elbasani fault zone is expressed by the diaper dome of Dumrea, Quaternary depression of Elbasani, and transversal structure of Labinoti. Analyses of spatial and temporal characteristics of the earthquake activity may supply significant clues for revealing the future seismic hazard along the VLED fault zone, and these anomaly regions may be interpreted as the locations of the next possible earthquakes [10]. Historical seismicity indicated that Elbasan has been destroyed by strong earthquakes.…”

Correlations between seismic b-value and heat flow density in Vlora-Lushnja-Elbasani-Dibra Fault Zone in Elbasani area, central Albania

“…This parameter tells us about the structure and features of the Earth's crust in an area in which earthquakes occurred. It is related to the type of rocks, how they are arranged, and their ductility under stress (Aki 1965;Wyss 1973;Fytikas 1980;Katsumata 2006;Utsu 1971;Bayrak, Öztürk 2004;Polat et al 2002;Öztürk, Bayrak 2012;Öztürk 2011;Ormeni et al 2017;Nanjo 2020;Ormeni et al 2022). However, the correlation between heat flow data and seismic b-value has not been studied intensively for different parts of the world.…”

“…However, the correlation between heat flow data and seismic b-value has not been studied intensively for different parts of the world. There are few studies for spatial and temporal evaluation of the b-value for different parts of Albania (Aliaj et al 2010;Ormeni 2015;Ormeni et al 2017;Özturk, Ormeni 2021). However, the correlation between the heat flow density and seismotectonic b-value was not studied for different zones of Albania.…”

“…Heat flow studies and 3D-seismic tomography can identify the Earth's crust and heterogeneity of the upper-most mantle. The changes in b-value from its average value of about 1.0 for different parts of Albania may result from many reasons such as heterogeneity or an increase in microcrack density (Aliaj et al 2010;Ormeni et al 2017;Öztürk, Ormeni 2021). If the Earth materials have different properties or lots of cracks, a large b-value may be observed.…”