Stress Field Inversion Analysis of Earthquake Focal Mechanisms in Northwestern Iran: Implications for Tectonic Regimes
Author(s):
Article Type:
Research/Original Article (دارای رتبه معتبر)
Abstract:
Understanding the stress field is crucial for assessing seismic risks in Northwestern Iran, a region known for its high seismic activity and geological volatility. The intricate tectonic arrangements involving the Arabian, Anatolian and Eurasian plates contribute to the unstable nature of the area. This study focuses on deducing stress regimes through stress inversion analysis of earthquake focal mechanisms in the North Tabriz Fault system. Analyzing the stress field is essential for understanding the elastic characteristics and geodynamics of the region. This study considers the stress field surrounding the Tabriz Fault, aiming to determine stress parameters and principal stress orientations using focal mechanisms. By analyzing 35 earthquake focal mechanism datasets from the Global Centered Moment Tensor and the Iranian Seismological Center, stress field inversions were conducted using Michael's linear inversion method and the iterative joint inversion method. The two techniques yielded distinct outcomes, with the iterative joint inversion method proving more accurate in determining stress fields and principal stress orientations. The Plunge values of and were observed to be relatively insignificant, measuring 3.24 and 2.06, respectively. A value close to 90 degrees, specifically 86.14, was determined for . The trend values for and were found to be 146.08 and 55.97, respectively, while exhibited a trend value of 293.51. To estimate the orientation of the maximum horizontal stress (SH), the iterative joint inversion method was employed, yielding an estimation of . The trend and plunge calculated from this method for , and were also utilized in this estimation. The findings indicate the existence of strike-slip faults in proximity to the North Tabriz Fault. The stress direction observed and the trajectory of the fault system suggest the influence of a transpressional mechanism. The predominant right-lateral strike-slip motion observed aligns with the prevailing tectonic regime in the region, providing evidence of strike-slip and thrust faulting stress regimes. The results contribute to a better understanding of the stress field and geodynamic situation in Northwestern Iran. They provide valuable insights for spatial analysis of future earthquakes and assessing seismic hazards in the region.
Keywords:
Language:
English
Published:
Journal of the Earth and Space Physics, Volume:49 Issue: 4, Winter 2024
Pages:
105 to 119
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