Regional pattern of the earth's crust dislocations on the territory of Bulgaria inferred from gravity data and its recognition in the spatial distribution of seismicity
Regular Research Article
29 Apr 2013
1National Institute of Geophysics, Geodesy and Geography, Bulgarian Academy of Sciences, Acad. G. Bonchev St., bl.3, 1113 Sofia, Bulgaria
2University of Mining and Geology, St. Ivan Rilski, Sofia, Bulgaria
Abstract. Deformations in the earth's upper layer can be mapped using a variety of methods and techniques. This paper examines the regional pattern of linear structures on the territory of Bulgaria using Bouguer gravity anomalies. The gravity data were analyzed using integrated gradient interpretation techniques, such as the Total Horizontal Gradient (THG) and Vertical Gravity Gradient (VGG). Derived gravity maps reveal persistent lateral changes in density caused by faults, thrusts or dislocated block borders. We thoroughly examine and describe the observed lineation pattern and relate it to the existing tectonostratigraphic information. Several decades after the earliest attempts of potential field data application for revealing first order faults and crustal blocks in the Bulgarian territory, we take advantage of improved techniques and high quality gravity and seismological data for more reliable estimation of the seismogenic potential of faults and thrust structures in the earth's crust. The interpreted structural elements are compared with the epicentral map and epicentral density function of the examined area, to evidence relations between the revealed structures and seismicity. The study indicates possible seismological significance of these lineations and motivates the interest of further quantitative investigations for the purposes of seismic hazard assessment.