Sürdürülebilir Kalkınma Amaçları
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- BildiriYalnız künye2026Scopus SJRQ4Residual-Based Evaluation of Basin and Basin Edge Effects in Türkiye: Implications for Regional Site Amplification Modeling
İçen, Abdullah; Ilki, A.; Goksu, C.; Cinar, T.; Erdik, M.
This study investigates basin, basin edge and complex topography effects in ground motion records using residuals from empirical ground motion models, to better understand regional site amplification patterns in Türkiye. Using data from the updated Strong Motion Database of Türkiye (SMD-TR) strong-motion database, we compute residuals using site amplification function and analyze their spatial distribution across regions. The clustering technique, Gaussian Mixture Models (GMM), is employed to identify regions with coherent residual patterns, primarily to capture regional site effects. After regionalization, peak amplifications within the VS30 range of 400–550 m/s are examined for potential associations with sedimentary basins or basin edge effects. The results reveal systematic amplification anomalies within the VS30 range of 400–550 m/s that are not fully captured by conventional site proxies such as VS30. Notably, residuals consistently cluster along basin edges and within deep valley regions, indicating the influence of complex three-dimensional and topographic amplification mechanisms. These observations underscore the limitations of current site characterization approaches and motivate further refinement of site response models, particularly for partially non-ergodic applications in seismic hazard analysis. This study focuses on residual-based evaluations to identify potential basin, basin-edge, and topographic effects that warrant more detailed investigation.
- MakaleYalnız künye2026Scopus SJRQ1Regionalized Bayesian site amplification models for Türkiye
İçen, Abdullah
Accurate representation of site amplification is essential for seismic hazard analysis, particularly in regions with complex geological structure. This study develops a Bayesian hierarchical site amplification model that captures nonlinear, period-dependent, and regionally variable behavior using an extensive strong-motion dataset from Türkiye. The model employs a piecewise VS30 functional form derived from nonparametric scaling and clustering, and incorporates nonlinear scaling with reference rock motion intensity (PSArock). Regional variability is introduced through random-slope adjustments, enabling spatial differences in amplification to be represented while maintaining statistical stability through partial pooling. Results indicate pronounced nonlinear and regional variability for soft soils and reduced regional differences for stiff sites (VS30 > 600 m/s). A key observation is a systematic amplification peak within the 400–550 m/s velocity range, where the model exhibits consistent underprediction across periods. Because this feature persisted even for stations located on flat basin interiors, a detailed investigation of stations in this VS30 interval was conducted and is presented in the study. Mapping and site-specific examination reveal that many of these stations are located near slope breaks, basin edges, or transitional geological settings, suggesting that 2D/3D wave-propagation or impedance-transition effects—rather than VS30 alone—may drive the increase in the amplification. Additionally, residual underprediction persists at high-VS30 rock sites, highlighting the need for improved empirical characterization of stiff-soil and rock conditions. Overall, the proposed Bayesian framework provides a flexible, data-driven, and uncertainty-aware approach for modeling site amplification, with direct applications in probabilistic seismic hazard analysis and performance-based earthquake engineering.
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İncele - MakaleAçık Erişim2025Scopus SJRQ2A New Ground-Motion Prediction Model for Shallow Crustal Earthquakes in Türkiye
Çeken, Ulubey; Sertçelik, Fadime; İçen, Abdullah
The recent expansion of the strong-motion observation network, along with the increase in data obtained during major earthquakes and efforts to create consistent metadata for source, path, and site effects for both old and new records, has significantly improved the quality of data and the level of modeling in Türkiye. The mainshock and aftershock records of the 6 February 2023 Kahramanmaraş earthquake doublet (MW 7.8 and 7.7), which are among the most destructive earthquakes in world history, constitute an up-to-date and important data source for this study. In this study, we present new ground-motion prediction models (GMPMs) for shallow crustal earthquakes using strong-motion data recorded in Türkiye. Our GMPMs are calibrated using 20,173 strong-motion records from 1565 shallow crustal earthquakes with depths of less than 35 km that occurred in Türkiye and its vicinity between 1976 and 2023. Our model is valid for magnitudes ranging from 4.0 to 7.8 (MW), and for the time-averaged 30 m shear wave velocity (VS30) values of 975 stations, which ranged from 131 to 1862 m/s. In the analyses performed, using the recently developed site amplification model, we calculated the model coefficients using the mixed-effects regression algorithms used by the GMPM developers. Additionally, a heteroscedastic model was created for aleatory variability as a function of MW. The closest distance to the surface projection of the fault plane (RJB) is between 0 and 350 km. Using the metadata prepared according to these criteria, we derived up-to-date ground-motion prediction models for horizontal-component peak ground velocity (PGV), peak ground acceleration (PGA), and 5% damped pseudo-spectral acceleration (PSA) response spectra, at 36 periods ranging from 0.01 to 10 s. The variability in the predictions was decomposed into within-event, between-event, and site-to-site deviations to determine the total standard deviations (σ). Compared to previous models, the proposed GMPMs were developed using a much richer database with recent major earthquakes, and the consistent estimates and lower residuals in the comparisons support the reliability of the models.
AtıfScopus4WoS3OpenAlex4İncele - Veri SetiYalnız künye2024Scopus SJRQ1An updated strong-motion database of Türkiye (SMD-TR)
Sandıkkaya, M Abdullah; Güryuva, Baran; Kale, Özkan; Okçu, Oğuz; İçen, Abdullah; Yenier, Emrah; Akkar, Sinan
We updated the earthquake strong-motion database of Türkiye (SMD-TR) that is initially compiled by Akkar et al. The updated data set consists of of 9244 earthquakes of magnitudes 3.0 ≤ M ≤ 7.8 that occurred between 1976 and 2023. It includes 95,890 three-component waveforms recorded at 1022 stations (55,375 records that are processed from 6710 events and 974 stations). The database is disseminated under research-oriented website DesignSafe (https://doi.org/10.17603/ds2-f21x-s189) and is compiled to provide ground-motion flatfile, which will be updated periodically until 2025. The released version includes events occurred in Türkiye until 28 February 2023, and hence, it comprises of the mainshocks and a great portion of aftershocks from the February 6th, 2023, Kahramanmaraş earthquakes. The database includes event metadata compiled from national and international seismological agencies as well as the literature. We classified events according to their tectonic environments (i.e. active crustal and subduction) and identified the aftershocks. The station information provided by AFAD1 was used to compute the major site parameters, including time-based average of shear-wave velocity of uppermost 30 m (VS30) and depth-to-rock horizon at which the shear-wave velocity (VS) attains 1 km/s (Z1). We also computed the finite-fault distance metrics and flagged the stations located on the hanging-wall side of the rupture, as well as identified pulse-like records. We developed an automatic processing algorithm to determine the waveform quality, apply appropriate filtercut-offs to remove low- and high-frequency noise, and compute ground-motion parameters. The automatic processing was applied to small-magnitude (M < 5.5) events, whereas manual processing scheme is preferred for waveforms recorded from larger events (M ≥ 5.5). The peak ground-motion values, spectral ordinates, and ground-motion duration are provided along with the key data processing parameters in the flatfile.
AtıfScopus28OpenAlex33İncele - MakaleAçık Erişim2024Scopus SJRQ1Local site effects at the selected stations affected by the February 6 2023 Türkiye Earthquake Sequences
Ilhan, Okan; Indır, Onur; Muratoğlu, Gamze; İçen, Abdullah; Albayrak, Kubilay; Sandıkkaya, M. Abdullah; Askan, Ayşegül; Arduino, Pedro; Taciroğlu, Ertuğrul
This paper explores the applicability of one-dimensional (1D) nonlinear (NL) and equivalent-linear (EL) site response analyses (SRA) for characterizing site effects at selected strong ground motion stations impacted by the February 6, 2023 Türkiye earthquakes. The 1D NL simulations generally underestimate site response at softer sites and for long periods likely due to basin effects and the uncertainties associated with site properties and the 1D approximation. The inclusion of the high-frequency spectral decay parameter (κ0) in 1D simulations decreases the prediction bias of nonlinear SRA, especially at soft sites for short periods. Moreover, the theoretical transfer functions (TTFs) are demonstrated to capture the fundamental site period through in horizontal-to-spectral vertical ratio (HVSR) using ground motion data before and after the February 6, 2023 main event.
AtıfScopus22OpenAlex27İncele - MakaleYalnız künye2023Scopus SJRQ1Region Specific Ground-Motion Predictive Models for Shallow Active Regions
İçen, Abdullah; Sandikkaya, M. Abdullah
Using a global dataset, we propose a series of ground-motion predictive models for acceleration response spectra. The proposed models include regional adjustments to source, path, and site terms with nonlinear soil behavior. The regression coefficients are computed using linear and nonlinear mixed-effect regression algorithms. Furthermore, we develop heteroscedastic variability models for between-event, site-to-site, and single-site standard deviations. The between-event sigma model depends solely on magnitude, but the single-site standard deviation model depends on both magnitude and distance. Finally, the site-to-site standard deviation model is given in terms of VS30 and spectral acceleration at rock site condition.
AtıfScopus7WoS7OpenAlex9İncele