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<p>Coulomb stress change (ΔCFS) is widely used to evaluate static earthquake triggering, yet threshold-based triggering statistics can be sensitive to assumptions about fault friction, including possible fluid-related weakening, and to hypocentral uncertainty. Using the 2024 Noto <i>M</i><sub>W</sub>7.5 earthquake sequence, we compute static ΔCFS for (i) the <i>M</i><sub>W</sub>5.5 foreshock acting on the <i>M</i><sub>W</sub>7.5 mainshock receiver plane and (ii) the mainshock acting on early aftershocks within the first 51.5&#xa0;h. To represent plausible time-varying fault strength potentially influenced by fluids, we convert a friction scenario <i>μ</i>(<i>t</i>) into effective friction <i>μ′</i>(<i>t</i>) under isotropic poroelastic relations for two upper-crustal end members, and evaluate ΔCFS at each aftershock’s reported hypocentral longitude, latitude, and depth. The foreshock yields positive ΔCFS on nodal plane II of the mainshock (~ 0.02 – 0.03&#xa0;MPa for <i>μ′</i> = 0.17 – 0.25), exceeding the commonly used 0.01&#xa0;MPa benchmark. For 2,982 aftershocks, the fractions with ΔCFS ≥ 0.01&#xa0;MPa are ~ 39 – 46% across four-time windows (ΔCFS ≥ 0.05&#xa0;MPa: ~ 36 – 44%), while perturbing hypocenters within location uncertainties produces broad 90% intervals (~ 30 – 58%). Sensitivity tests show that the threshold-based triggering fraction increases monotonically with <i>μ′</i> over 0.20 – 0.80, underscoring the dependence of ΔCFS statistics on frictional assumptions. Deformation and stress calculations indicate hanging-wall uplift and footwall subsidence consistent with reverse faulting, and a heterogeneous horizontal stress field at ~ 10&#xa0;km depth characterized by NW–SE extension and NE–SW compression. Overall, these results provide a quantitative reference for interpreting ΔCFS-based triggering in the Noto sequence while highlighting key sensitivities in fixed-threshold metrics.</p>

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Regional coulomb stress changes and stress triggering mechanisms of the noto MW7.5 earthquake

  • 期刊论文

  • 发表日期：

    2026年3月14日

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  • Mingyue Zhou,
  • Zhitong Jin,
  • Yongge Wan,
  • Zhaoxuan Guan

摘要

Coulomb stress change (ΔCFS) is widely used to evaluate static earthquake triggering, yet threshold-based triggering statistics can be sensitive to assumptions about fault friction, including possible fluid-related weakening, and to hypocentral uncertainty. Using the 2024 Noto MW7.5 earthquake sequence, we compute static ΔCFS for (i) the MW5.5 foreshock acting on the MW7.5 mainshock receiver plane and (ii) the mainshock acting on early aftershocks within the first 51.5 h. To represent plausible time-varying fault strength potentially influenced by fluids, we convert a friction scenario μ(t) into effective friction μ′(t) under isotropic poroelastic relations for two upper-crustal end members, and evaluate ΔCFS at each aftershock’s reported hypocentral longitude, latitude, and depth. The foreshock yields positive ΔCFS on nodal plane II of the mainshock (~ 0.02 – 0.03 MPa for μ′ = 0.17 – 0.25), exceeding the commonly used 0.01 MPa benchmark. For 2,982 aftershocks, the fractions with ΔCFS ≥ 0.01 MPa are ~ 39 – 46% across four-time windows (ΔCFS ≥ 0.05 MPa: ~ 36 – 44%), while perturbing hypocenters within location uncertainties produces broad 90% intervals (~ 30 – 58%). Sensitivity tests show that the threshold-based triggering fraction increases monotonically with μ′ over 0.20 – 0.80, underscoring the dependence of ΔCFS statistics on frictional assumptions. Deformation and stress calculations indicate hanging-wall uplift and footwall subsidence consistent with reverse faulting, and a heterogeneous horizontal stress field at ~ 10 km depth characterized by NW–SE extension and NE–SW compression. Overall, these results provide a quantitative reference for interpreting ΔCFS-based triggering in the Noto sequence while highlighting key sensitivities in fixed-threshold metrics.