Seismicity and Seismotectonics Study in Southwestern Albania Using a Local Dense Seismic Network

Abstract

The Albanides represent a complex orogen made up of a heterogeneous tectonic nappe pile of Paleozoic, Mesozoic, and Cenozoic domains. Albania is tectonically active, and moderate to strong earthquakes have occurred in the past. However, abundant microseismicity has not been monitored and studied by a dense seismic network. During this study, a seismic network of 40 stations was deployed in southern Albania for one year. A total of 2113 microearthquakes were well located. The most accurately located events and 810 focal mechanisms were used in order to define the seismotectonics and the stress pattern in the area. Results indicate that thrust and strike-slip faulting both exist in southwestern Albania, suggesting a continuation of the complex tectonic setting of the neighboring northwestern Greece to the north.

Present‐day crustal stress field in Greece inferred from regional‐scale damped inversion of earthquake focal mechanisms

“…Serpetsidaki et al . [] repeated the same analysis in SW Albania, using again a temporary seismic network of 40 stations but a much larger data set (~810 solutions). This time the stress inversion results in all six subareas are in general consistent with ours, both for σ 1 axes (azimuths from N62°E to N233°E, plunges 3°–30°) and σ 3 axes (azimuths from N91°E to N318°E).…”

“…Based on analysis of gravity observations, Shaw and Jackson [2010] suggested that the elastic part of the Ionian Sea lithosphere is flexed owing to the SW motion along KTF, which may explain the presence of a thrust component. Along Epirus and southern Albania low-angle thrust faulting dominates as a result of the continent-continent collision [Hatzfeld et al, 1995;Tselentis et al, 2006;Serpetsidaki et al, 2012]. To the south of Zakynthos lowangle thrust faulting occurs at the shallow dipping interface of the subduction.…”

“…Taking into account that most of the earthquakes the authors used were actually smaller than magnitude 3.0, we conclude that any differences reflect the influence of local stresses. Serpetsidaki et al [2012] repeated the same analysis in SW Albania, using again a temporary seismic network of 40 stations but a much larger data set (~810 solutions). This time the stress inversion results in all six subareas are in general consistent with ours, both for σ 1 axes (azimuths from N62°E to N233°E, plunges 3°-30°) and σ 3 axes (azimuths from N91°E to N318°E).…”

“…Despite the fact that geodetic studies have resolved relatively well the strain field in the Aegean and mainland Greece, the crustal stress field is known in much less detail. Previously published studies derived present-day stress either by using P and T axes of earthquake focal mechanisms [e.g., Hatzfeld et al, 1990Hatzfeld et al, , 1995Hatzfeld et al, , 1999 or by inverting a limited number of earthquake focal mechanisms and obtaining the stress tensor for subjectively chosen subareas [Kiratzi, 2002;Bohnhoff et al, 2005;Ganas et al, 2005;Tselentis et al, 2006;Konstantinou et al, 2011;Serpetsidaki et al, 2012;Friederich et al, 2014]. In this work, we present new crustal stress data of unprecedented detail for Greece inferred from the inversion of 1614 earthquake focal mechanism solutions by using the method of Hardebeck and Michael [2006].…”

Analysis of global navigation satellite system data along the Southern Gas Corridor and estimate of the expected displacements

“…north-northeast (AG01, AG02, AG03, AG14, and AG15 sites), the GPS stations on the Albanian shoreline (GNSS stations KRYE, APOL, and RRAD) point toward the north-northwest ( Figure 2). The strain velocities in the internal region of southern Albania (GNSS stations LABO, DERV, and LESK) are perfectly parallel to the west-southwest direction of convergence, as documented by the slip vectors on the principal thrusts (Muço, 1994;Louvari et al, 2001;Serpetsidaki et al, 2012). This remarkable difference in the direction from the coastal to the internal sector is likely because of a strong mechanical coupling characterizing the Karaburuni-Sezani detachment (ALCS201) and the Durresi Offshore thrust (ALCS315).…”