The Zagros is known as one of the most seismically active mountain belts on Earth. In this study, we apply the parametric generalized inversion technique to estimate the source (i.e., moment magnitude, corner frequency, and stress parameter), path (i.e., quality factor and geometric attenuation slope), and site parameters for the entire Zagros mountains. We rely on strong ground motion records from 264 earthquakes (3.0 ≤ Mw ≤ 6.5) between 1976 and 2020, recorded by 241 three-component accelerometers. We find stress-parameter values ranging from 0.07 MPa to 32.9 MPa, with an average of 4.47 MPa, showing no clear dependence on magnitude. The estimated geometric attenuation and corresponding quality factor are, <InlineEquation ID="IEq1"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="24_2025_3829_Article_IEq1.gif" Format="GIF" Height="16" Rendition="HTML" Resolution="72" Type="Linedraw" Width="128" /> </InlineMediaObject> <EquationSource Format="TEX">$\gamma =1.012\pm 0.009$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>γ</mi> <mo>=</mo> <mn>1.012</mn> <mo>±</mo> <mn>0.009</mn> </mrow> </math></EquationSource> </InlineEquation>, and <InlineEquation ID="IEq2"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="24_2025_3829_Article_IEq2.gif" Format="GIF" Height="21" Rendition="HTML" Resolution="72" Type="Linedraw" Width="117" /> </InlineMediaObject> <EquationSource Format="TEX">$Q=\left(159\right){f}^{\left(0.49\right)}$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>Q</mi> <mo>=</mo> <mfenced close=")" open="("> <mn>159</mn> </mfenced> <msup> <mrow> <mi>f</mi> </mrow> <mfenced close=")" open="("> <mn>0.49</mn> </mfenced> </msup> </mrow> </math></EquationSource> </InlineEquation>, respectively. The mean value of near-surface attenuation, from regression of high-frequency empirical site transfer functions, is κ0 = 0.0351 ± 0.0299 s. Furthermore, we observe a weak correlation between κ0 and VS30. Our results present updated values for ground motion parameters (i.e., stress parameter, near-surface attenuation, quality factor and geometric attenuation slope) in the Zagros.

Estimating Seismic Sources, Paths, and Site Parameters in the Zagros Mountains (Iran), Based on Non-linear Inversion

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发表日期：

2025年9月20日

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Mehran Davatgari-Tafreshi,
Mohammadreza Jamalreyhani,
Dino Bindi

摘要

The Zagros is known as one of the most seismically active mountain belts on Earth. In this study, we apply the parametric generalized inversion technique to estimate the source (i.e., moment magnitude, corner frequency, and stress parameter), path (i.e., quality factor and geometric attenuation slope), and site parameters for the entire Zagros mountains. We rely on strong ground motion records from 264 earthquakes (3.0 ≤ M_w ≤ 6.5) between 1976 and 2020, recorded by 241 three-component accelerometers. We find stress-parameter values ranging from 0.07 MPa to 32.9 MPa, with an average of 4.47 MPa, showing no clear dependence on magnitude. The estimated geometric attenuation and corresponding quality factor are, $\gamma =1.012\pm 0.009$ $γ = 1.012 \pm 0.009$ , and $Q=\left(159\right){f}^{\left(0.49\right)}$ $Q = (159) f^{(0.49)}$ , respectively. The mean value of near-surface attenuation, from regression of high-frequency empirical site transfer functions, is κ₀ = 0.0351 ± 0.0299 s. Furthermore, we observe a weak correlation between κ₀ and V_S30. Our results present updated values for ground motion parameters (i.e., stress parameter, near-surface attenuation, quality factor and geometric attenuation slope) in the Zagros.