Iranian Journal of Geophysics

Iranian Journal of Geophysics

Investigation of the seismic parameter b value and the fractal seismicity dimension (Dc value) in relation to the 2017 Sarpol Zahab–Ezgeleh earthquake

Document Type : Research Article

Authors
Muhammed Hossein Mousavi 1
Amir Talebi 2
Faegheh Mina Araghi 2
1 M.Sc., Department of Physics Education, Farhangian University, Tehran, Iran
2 Assistant Professor, Department of Physics, Faculty of Science, Arak University, Arak, Iran
10.30499/ijg.2025.530992.1710
Abstract
The 7.3 magnitude Serpel Zahab earthquake, which occurred on November 12, 2017, in the Zagros region, underscores the need for thorough seismic hazard analyses in this active tectonic zone. In the present study, the spatiotemporal variations of the seismic parameters b-value and DC-value in the vicinity of the earthquake were examined using an integrated earthquake catalog recorded by the National Seismological Center (IRSC) during the period from January 1, 2006, to October 31, 2024. The results indicate that in the active tectonic segments, the b-value varied between 0.4 and 1.4, a reduction in this parameter adjacent to the fault prior to the mainshock suggests stress accumulation and the potential for an imminent rupture. In contrast, an increase in the DC-value reflects enhanced heterogeneity in the fault structure and a more complex fracture mechanism nearing failure. Immediately following the main event, a significant increase in the b-value was observed, indicative of stress release through smaller aftershocks, alongside a decrease in the DC-value. The temporal analysis of the b-value revealed a decreasing trend before and a pronounced increasing trend after the earthquake, attributable to stress redistribution within the region’s geological framework. Additionally, low b-value values (less than 0.5) at depths between 10 and 20 kilometers confirm a concentration of stress within this depth interval. These findings clearly demonstrate the complementary roles of the b-value and DC-value in characterizing seismic behavior, assessing fault evolution, and understanding the tectonic processes in reverse, strike-slip, and extensional faults of the Zagros region. The obtained results serve as a crucial tool for evaluating seismic hazard in tectonically active areas.
Keywords
b-value
DC-value
Sarpol Zahab
seismotectonics
Zagros
Subjects
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Iranian Journal of Geophysics
Volume 20, Issue 4
September and October 2026
Pages 1-16

  • Receive Date 23 June 2025
  • Revise Date 16 September 2025
  • Accept Date 25 October 2025
  • First Publish Date 16 May 2026
  • Publish Date 23 July 2026