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STRESS INVERSION FROM FOCAL MECHANISM OF MODERATE EARTHQUAKES IN ALBANIA
Abstract
The present study seeks to relate the focal mechanisms of moderate earthquakes, regional tectonics and the tectonic stress distribution, in Albania. We have analyzed 33 moderate earthquakes (2.2 ? MW ? 4.9) recorded in the time period 2013-2015, by the Albanian broadband (BB) seismic network. Events were located within the upper crust, in the depth range 0 ? h ? 17 km, showing the present day active tectonics. Formal stress inversion of the focal mechanism data, support the variation in the direction of the actual stress field as well as of the stress index R?, between the outer and the inner tectonic domains in Albanian, respectively under a compressional and extensional tectonic regime. Both domains are connected through Vlora-Lushnja-Elbasani-Dibra (VLED) transversal source zone, characterized by normal faulting with a strong strike-slip component. Orientation of the stress axes, ?1, ?2 and ?3, vary according to the respective zones. Thus, along the Adriatic coastal region, stresses have the orientation ?1(2?/66?), ?2(20?/335?) and ?3(70?/162?) showing a compressional stress regime (R = 0.15) directed E-NE (N65?E), while in the Ionian region it changes to ?1(31?/260?), ?2(17?/159?) and ?3(53?/45?), showing a compressional stress regime (R = 0.5) directed to EW (N94?S); In the inner domain of an extensional regime (R = 0.98), stress axis results oriented ?1(55?/116?), ?2(2?/24?), ?3(34?/292?), having a NE (N22?E) direction; Along the transversal zone (VLED), of oblique displacements (R= 0.49), results support the orientation ?1(20?/1?), ?2(67?/152?), and ?3 (10?/267?), where the horizontal stresses are directed almost southward (N178?E). Focal mechanism solutions and horizontal stresses SHmax and SHmin, inferred from the formal stress inversion of focal mechanism data, show a good agreement with previous studies and support the continental collision mechanism between Adria microplate and Albanian orogen.
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References14
Muço B., The collision between Adria and Albanian orogen on the light of focal mechanism solutions, 10th European Conference on Earthquake Engineering, Duma (ed.) © 1995 Balkema, Rotterdam, ISBN 90 5410 528 3,1995;
Jouanne F., Mugnier L. J., Koci R., Bushati S., Matev K., Kuka N., Shinko I., Kociu S., Duni L., GPS constraints on current tectonics of Albania, Netherlands, Tectonophysics, Vol. 554–557, pp. 50-62, 2012.
Sulstarova E., Peçi V., Shuteriqi P., Vlora-Elbasani-Dibra (Albania) transversal fault zone and its seismic activity, Journal of Seismology, Netherlands, Vol. 4, Issue 2, pp 117–131, 2000;
Dushi E., Minarolli A., Kasaj E., Gjuzi O., Focal mechanism solutions for local earthquakes (M > 3.0), from Albanian Seismological Network (ASN), broadband recordings, XX Congress of the Carpathian Balkan Geological Association, Tirana, Albania, special issue - ISSN: 0254-5276, pp. 256, 2014.
Muço B., Focal mechanism solutions for Albanian earthquakes for the years 1964 - 1988, Netherlands, Tectonophysics, vol. 231, pp 311-323, 1994;
Kiratzi A., Dimakis E., Focal mechanism and slip models of moderate size earthquakes in Albania and adjacent countries, Italy, Ital J. Geosci. (Boll. Soc. Geol. It), Vol. 131, issue 2, (DOI: 10.33.01/IJG.2011.3.3), pp 00-00, 2012;
Baker C., Hatzfeld D., Caen L. H., Papadimitriou E., Alexis R., Earthquake mechanism of Adriatic Sea and Western Greece: implications for the oceanic subduction-continental collision transition, Geophysical Journal International, Italy Vol. 131, Issue: 3, pp 559-594, 1997;
Prondelli S., Morelli A., Boschi E., Seismic deformation in the Mediterranean area estimated by moment tensor summation, Geophys. J. Int., No. 122, pp. 938–952, 1995.
Klein, F.W., HYPOINVERSE, a program for VAX computers to solve for earthquake locations and magnitudes, U.S. Geological Survey Open-File Report 89-314, 59 pp. 1989;
Lienert R. B., Berg E., Frazer L. N., HYPOCENTER: An earthquake location method using centered, scaled, and adaptively damped least squares. Bulletin of the Seismological Society of America, Vol. 76, issue 3, pp. 771–783, 1986;
Zoback M. L., First and second order patterns of stress in the lithosphere: The World Stress Map Project, J. Geophys. Res., No. 97, pp. 11703-11728, 1992.
Hardebeck L. J., Shearer M. P., Using S/P amplitude ratios to constrain the focal mechanisms of small earthquakes, California, USA, BSSA, Vol. 93, No. 6, pp. 2434–2444, 2003.
Snoke J. A., Munsey W. J., Teague G. A., Bollinger A. G., A program for focal mechanism determination by combined used of polarity and SV-P amplitude ratio data, Earth. Notes., No. 55, pp. 15, 1984.
Delvaux D., Sperner B., New aspects of tectonic stress inversion with reference to the TENSOR program, Geological Society, London, Special Publications, London, 212, pp 75-100, 2003;
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