Empirical spectral amplification modeling for near-fault ground motions: Evidence and modification factors from the 2023 Kahramanmaraş earthquake sequence

Ömer Faruk Nemutlu , Mohamed Freeshah

Abstract

Near-fault ground motions are often influenced by forward rupture directivity effects, which may generate distinctive long-period velocity pulses and substantially increase seismic demands compared to far-field records. However, conventional design spectra prescribed in seismic codes generally fail to incorporate these near-fault characteristics, potentially resulting in unconservative structural designs. This study examines the spectral amplification associated with near-fault effects and introduces a coefficient-based modification approach derived through regression analysis. A total of 20 ground motion records from the 6 February 2023 Mw 7.7 Pazarcik earthquake were employed - 10 near-fault and 10 far-field - and to account for the bidirectional nature of seismic excitation, both the East-West (EW) and North-South (NS) components were analyzed separately, yielding 40 datasets. Five-percent-damped elastic acceleration response spectra were computed using the Newmark-Beta method across a broad period range, after which average spectra for the near-fault and far-field groups were compared and spectral ratios were calculated to quantify amplification due to fault proximity. The period range was classified into short (T

Key Words

coefficient-based modification; near-fault ground motions; Pazarcik earthquake; seismic design; spectral amplification

Address

Ömer Faruk Nemutlu — Civil Engineering Department, Faculty of Engineering and Architecture, Bingol University, Bingol, Türkiye
Mohamed Freeshah — Civil and Environmental Engineering Department, College of Engineering, United Arab Emirates University, Khalifa Bin Zayed St., Al Ain P.O. Box 15551, United Arab Emirates

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