Seismotectonics and structural dynamics of the eastern Sulaiman fold-and-thrust belt, Pakistan

Structural and kinematic analyses of the eastern Sulaiman Range, based on focal mechanism solutions reveal systematic spatial variations in faulting style. Thrust-dominated deformation characterizes the eastern and western parts of the study area, whereas the central region is dominated by left-lateral strike-slip faulting that is spatially associated with the Kingri fault system. The present-day stress field is characterized by a NW–SE-oriented maximum horizontal compressive stress (SHmax), consistent with ongoing oblique convergence between the Indian and Eurasian plates. These observations suggest that the present-day deformation is primarily governed by regional compressional stresses expressed through thrust faulting, while secondary stresses associated with mechanical resistance from the rigid Katawaz block may locally impede northward motion of the Indian plate and promote lateral strain partitioning through strike-slip faulting. This interaction may contribute to fault curvature, the development of en-echelon structural geometries, and the observed spatial variability in deformation across the Sulaiman fold-and-thrust belt. The spatial distribution and kinematics of the focal mechanism solutions are broadly consistent with a simple Riedel shear framework, although this interpretation remains preliminary. Frequency–magnitude analysis further reveals relatively higher Gutenberg–Richter b-values for strike-slip earthquakes than for thrust-faulting events, indicating greater structural complexity and fault heterogeneity within the strike-slip domain.