Work

Assessment of Nonlinear Site Response Using eHVSRs During the 2023 Kahramanmaraş Earthquake Sequence

Year: 2026

Type: article

Abstract: This study presents the first evaluation of the degree of nonlinearity in site response at strong-motion stations in Türkiye during the 6 February 2023 Kahramanmaraş earthquake sequence (Mw 7.8 and Mw 7.5) using earthquake horizontal-to-vertical spectral ratios (eHVSRs). The analysis uses 2050 weak-motion and 175 strong-motion records from 24 AFAD stations in the Kahramanmaraş and Hatay regions, where some of the strongest ground motions and most severe damage were observed. The selected stations cover a broad range of site conditions, from soft alluvial deposits to relatively stiff sites, as characterized by Vs30. Conventional assessments of nonlinear site response generally rely on peak ground-motion measures and one-dimensional site proxies, particularly Vs30. In contrast, this study evaluates nonlinear behavior within a record-based framework that accounts for the combined influence of source characteristics, propagation path, local site conditions, and basin-related wave effects. Nonlinear site response is quantified by comparing strong-motion and weak-motion eHVSR spectra, where the weak-motion reference is derived from records with peak ground velocity (PGV) lower than 1 cm/s. A principal methodological contribution is the use of record-specific S-wave windows selected according to the event-dependent energy content of each record, rather than a uniform fixed-duration window. This energy-based procedure focuses on the dominant S-wave energy while reducing pre-event noise and late-arriving coda effects. Incorporating record-specific S-wave duration improves degree of nonlinearity (DNL) estimates, proving that nonlinear response is driven not just by peak amplitude and near-surface stiffness but also by duration-dependent cyclic deformation demand. The proposed framework provides record-based constraints for empirical ground-motion models and regional three-dimensional physics-based earthquake simulations.

Source: Applied Sciences

DOI: 10.3390/app16178394

Authors: Bilal Özaslan, Mehmet Mustafa Önal

Institution: Ahi Evran University

Language: English

Topic: Seismic Performance and Analysis

Subfield: Civil and Structural Engineering

Field: Engineering

Domain: Physical Sciences

Open Access status: gold

Estimated APC paid: $2,896

Funder: Türkiye Bilimsel ve Teknolojik Araştırma Kurumu