Moderate earthquakes in Albania during 2009 and their associated seismogenic zones

Rrapo Ormeni(1), Siasi Kociu(2), Akli Fundo(3), Shkelqim Daja(4) & Viktor Doda(1)
(1) Polytechnic University, Institute of GeoSciences, Energy, Water and Environment Tirane, Albania "Don Bosko" street, Nr. 60. E-mail: rrapo55@yahoo.com, E-mail: vdoda@yahoo.com (2) Professor on leave from Institute of Seismology Tirane, JPMorgan Chase Bank, Chicago, IL, USA. E-mail: smkociu@hotmail.com (3) Polytechnic University, Tirane, Albania, "Mother Tereza" square. E-mail: aklifundo@yahoo.com (4) Polytechnic University, Mining and Geology Faculty, Tirane, Albania, "Elbasani" street. E-mail: dajash@yahoo.com

In 2009, moderate earthquakes occurred in the Lezha-Ulqini and Lushnje-Elbasani-Dibra seismogenic zones in Albania. The earthquake of 21 August 2009 (ML 5.0) occurred in the Adriatic Sea near the town of Ulqini at the Albania-Montenegro border. The mainshock was located 9 km southeast of the epicentre of the 15 April 1979 Ms 7.1 earthquake that caused loss of life and considerable damage to buildings in Montenegro and Albania. The earthquake of 6 September 2009 (ML 5.4) occurred in Gjorica, at the eastern Albania- the former Yugoslav Republic of Macedonia (FYROM) border, south of the city of Peshkopia, Albania. The mainshock of the 6 September 2009 earthquake was located 12 km northeast of the epicentre of the 30 November 1967, Dibra/Debar earthquake (Ms=6.7) that caused loss of life and considerable damage to buildings in Albania and FYROM. For this analysis, the local and regional data concerning the epicentral locations, focal mechanisms, macroseismic data of the mainshocks, and their aftershock activity were used. Based on the focal mechanisms, the motion of the 21 August 2009 earthquakes was pure thrust with compressional axes NE-SW, and the 6 September 2009 earthquake occurred on a normal fault with a NW-SE strike direction of tensional stress. The region affected by the August 2009 sequence, together with the seismogenic region of the 1979 Ulqini event, forms a roughly NW-SEtrending active seismotectonic zone in western Albania and continues through southern Montenegro. The region affected by the September 2009 sequence, together with the seismogenic region of the 1967 Dibra event, forms a roughly NE−SW-trending active seismotectonic zone in eastern Albania that continues in the western FYROM. Both zones present a threat to the nearby urban areas in Albania, Montenegro and the FYROM.

Adriatic Sea, earthquake, Gjorica earthquake, focal mechanism, faults, aftershocks.