Estimating slip rate and geological moment in non-parallel structural zones: A case study of the Sistan and Makran zones in eastern and southeastern Iran

Abstract

This paper reports the slip rate and geological moment rate of the seismically active non-parallel structural zones of Makran and Sistan. The long-term slip rate and geological moment are crucial for evaluating fault activity. Field surveys and remote sensing techniques were used to estimate fault slip rates, which were subsequently applied to calculate the geological moment. We provide the first quantitative estimation of Quaternary slip rates for key faults in the Sistan and Makran zones, including the Zahedan, Gosht, Johl Darak, Sedich, Darpahn, Saravan, and Qasr-e Qand, with estimated slip rates of 1.53, 1.20, 1.33, 1.36, 2.60, 5.82, and 3.57 mm/yr, respectively. Fault slip rates and geometric characteristics (strike, dip, and rake) were utilized to identify areas with high seismic potential. In the Makran zone, an analysis of 23 faults yielded an average geological moment of 1.0975E + 18 Nm/yr. Similarly, in the Sistan zone, analysis of 29 faults resulted in an average geological moment of 2.76783E + 17 Nm/yr. The highest geological moments in the Makran zone are observed along the Sabzevaran and Jiroft faults in the west, and the Saravan fault in the east, with estimated values of 2.96416 × 10¹⁸ Nm/yr, 2.81245 × 10¹⁸ Nm/yr, and 2.34318 × 10¹⁸ Nm/yr, respectively. In the Sistan zone, the Zahedan fault exhibits the highest geological moment, estimated at 1.67287 × 10¹⁸ Nm/yr. Makran seismicity is driven by the Arabian-Eurasian collision and the Indian-Eurasian stress field. Deformation in the Sistan zone is driven by N-NW strike-slip faults and NW-SE thrusts linked to Arabian plate movement.