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<p>The East Anatolian Fault Zone, a continental transform boundary within the Arabia-Eurasia collision zone, presents significant challenges for seismic hazard assessment due to complex structural segmentation and demonstrated cascading multi-segment rupture mechanisms. This investigation develops a probabilistic seismic hazard assessment (PSHA) framework for the East Anatolian Fault Zone (EAFZ), incorporating novel multi-segment rupture scenarios that address demonstrated cascading failure potential observed during the 6 February 2023 Mw 7.8 Kahramanmaraş earthquake sequence. The PSHA implementation through OpenQuake Engine employs a systematic 162-branch logic tree quantifying epistemic uncertainties across three source-model configurations: Individual Segments Model (ISM), Limited Multi-Segment Model (LMSM), and Extensive Multi-Segment Model (EMSM), combined with six regionally calibrated ground-motion prediction equations. Regional PSHA reveals severe seismic exposure with peak ground accelerations approaching 2.0&#xa0;g for 2475-year return periods along well-defined high-hazard corridors. Critical urban centers exhibit substantial exposure: 475-year rock-site PGA values of 0.567&#xa0;g (Elazığ) and 0.500&#xa0;g (Hatay/Antakya) exceed conventional design spectra. Spectral acceleration analysis reveals pronounced period-dependent characteristics with short-period Sa (0.3&#xa0;s) exceeding 2.2&#xa0;g and pronounced intermediate-period spectral acceleration reaching 0.98&#xa0;g at Sa(0.5&#xa0;s) for near-fault sites. Disaggregation analysis identifies systematic site-specific controlling earthquake scenarios, with near-source locations dominated by proximal large-magnitude events while off-fault sites depend on distant high-magnitude scenarios. Physics-based simulation (PBS) provides an independent consistency check of the regional seismo-tectonic framework through forward-modeling comparison against strong-motion recordings from the 2023 earthquake sequence using SPECFEM3D. The assessment demonstrates amplitude-level agreement across the near-fault station network, with synthetic-to-observed peak ground velocity ratios of 0.94–1.07, while identifying systematic peak ground acceleration underestimation of approximately 25%, attributable to the 3&#xa0;Hz bandwidth limitation of the simulation mesh and the absence of a stochastic high-frequency component. All reported PSHA hazard values are reference rock-site estimates (<i>V</i><sub>s30</sub>= 760&#xa0;m/s) requiring site-specific amplification for engineering design applications.</p>

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Comprehensive probabilistic seismic hazard assessment for the East Anatolian Fault Zone: a multi-segment rupture framework with physics-based seismo-tectonic assessment using the 2023 Kahramanmaraş earthquake sequence

  • 期刊论文

  • 发表日期：

    2026年7月27日

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  • Osamah H. M. Al-Dahlaki,
  • Jingxuan Zhao,
  • Zhenning Ba,
  • Sihan Cheng,
  • Yuekai Hu

摘要

The East Anatolian Fault Zone, a continental transform boundary within the Arabia-Eurasia collision zone, presents significant challenges for seismic hazard assessment due to complex structural segmentation and demonstrated cascading multi-segment rupture mechanisms. This investigation develops a probabilistic seismic hazard assessment (PSHA) framework for the East Anatolian Fault Zone (EAFZ), incorporating novel multi-segment rupture scenarios that address demonstrated cascading failure potential observed during the 6 February 2023 Mw 7.8 Kahramanmaraş earthquake sequence. The PSHA implementation through OpenQuake Engine employs a systematic 162-branch logic tree quantifying epistemic uncertainties across three source-model configurations: Individual Segments Model (ISM), Limited Multi-Segment Model (LMSM), and Extensive Multi-Segment Model (EMSM), combined with six regionally calibrated ground-motion prediction equations. Regional PSHA reveals severe seismic exposure with peak ground accelerations approaching 2.0 g for 2475-year return periods along well-defined high-hazard corridors. Critical urban centers exhibit substantial exposure: 475-year rock-site PGA values of 0.567 g (Elazığ) and 0.500 g (Hatay/Antakya) exceed conventional design spectra. Spectral acceleration analysis reveals pronounced period-dependent characteristics with short-period Sa (0.3 s) exceeding 2.2 g and pronounced intermediate-period spectral acceleration reaching 0.98 g at Sa(0.5 s) for near-fault sites. Disaggregation analysis identifies systematic site-specific controlling earthquake scenarios, with near-source locations dominated by proximal large-magnitude events while off-fault sites depend on distant high-magnitude scenarios. Physics-based simulation (PBS) provides an independent consistency check of the regional seismo-tectonic framework through forward-modeling comparison against strong-motion recordings from the 2023 earthquake sequence using SPECFEM3D. The assessment demonstrates amplitude-level agreement across the near-fault station network, with synthetic-to-observed peak ground velocity ratios of 0.94–1.07, while identifying systematic peak ground acceleration underestimation of approximately 25%, attributable to the 3 Hz bandwidth limitation of the simulation mesh and the absence of a stochastic high-frequency component. All reported PSHA hazard values are reference rock-site estimates (Vs30= 760 m/s) requiring site-specific amplification for engineering design applications.