Sürdürülebilir Kalkınma Amaçları

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• MakaleAçık Erişim2026/r/munzur/5985
  Effect of Source Parameter Variability on RVT-Based Site Response Analysis: A Case Study for the Aegean Region of Türkiye

  Icen, Abdullah

  This study investigates the influence of source parameter variability specifically stress drop and anelastic attenuation on site response analysis using the Random Vibration Theory (RVT) framework. Site amplifications were computed for a representative site in the Aegean region of Türkiye using four different source parameter sets based on regional literature. A single set of randomized Vs profiles was used to account for subsurface variability, while varying source models enabled the evaluation of epistemic uncertainty in site amplification. The epistemic uncertainty associated with source parameters, expressed as τsource, peaks at approximately 0.04 s, reflecting the sensitivity of high-frequency site response to stress drop and attenuation. The study provides a regionally calibrated quantification of source-parameter-driven epistemic uncertainty for the Aegean region. The findings emphasize the need to account for source-related uncertainty in seismic hazard assessment. Unlike most previous RVT-based studies, this work explicitly isolates and quantifies the effect of stress drop and attenuation on site amplification, highlighting a novel contributor to epistemic uncertainty. Future work should incorporate Monte Carlo simulation of source parameters to support PSHA applications.

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• MakaleAçık Erişim2026/r/munzur/5974
  Farklı Deprem Düzeylerinde Doğrusal Olmayan 1B Zemin Tepki Analizi ve TBDY (2018) ile Ampirik Büyütme Fonksiyonu Kıyaslaması

  Icen, Abdullah

  Bu çalışmada, Türkiye Bina Deprem Yönetmeliği (TBDY, 2018) kapsamında elde edilen DD-1, DD-2 ve DD-3 tasarım spektrumlarına uyumlu yer hareketleri kullanılarak bir boyutlu (1B) doğrusal olmayan zemin tepki analizleri gerçekleştirilmiştir. Analizlerde Hatay–İskenderun 3113 kuvvetli yer hareketi istasyonuna ait VS30 = 240 m/s hız profili kullanılmıştır. Kayıt seçimi, PEER NGA-West2 ve SMD-TR veri tabanlarından seçilmiştir. Her bir deprem düzeyi için doğrusal olmayan (NL) analizler uygulanmış; yüzey spektrumlarıyla taban spektrumlarının oranından periyot-bağımlı büyütme eğrileri elde edilmiştir. Elde edilen büyütme eğrilerinin ortalamaları, TBDY (2018)’de tanımlı Fs–F1 katsayıları ile ve İçen ve Sandıkkaya (2023) ampirik zemin büyütme modeliyle karşılaştırılmıştır. Sonuçlar, kısa periyot bölgesinde (T < 0.3 s) büyütmelerin yaklaşık 1 civarında olduğunu ve TBDY’nin Fs katsayılarının genel olarak konservatif bir yaklaşım sergilediğini göstermektedir. Uzun periyot bölgesinde (T > 0.6 s) ise büyütmelerin İçen ve Sandıkkaya (2023) modeliyle uyumlu olduğu, ancak TBDY’nin F1 katsayılarının bu bölgede daha düşük kaldığı ve dolayısıyla kısmen yetersiz tahminler ürettiği belirlenmiştir. Bu çalışma, farklı deprem şiddet düzeylerinde (DD-1–DD-3) doğrusal olmayan davranışın zemin büyütmesi üzerindeki etkisini nicel olarak ortaya koymakta ve TBDY (2018)’deki zemin büyütme katsayılarının özellikle uzun periyot bölgesinde yeniden kalibrasyon gerektirebileceğini göstermektedir.

  İncele
• MakaleAçık Erişim2026/r/munzur/5973
  Bayesian vs. Frequentist Mixed-Effects for Regional Site Amplification

  Icen, Abdullah

  Accurate treatment of regional site effects is essential for partially non-ergodic Ground-Motion Models (GMMs). This study compares a Bayesian hierarchical regression implemented with brms to a frequentist mixed-effects formulation using lmer for estimating period-dependent site amplification. Both models adopt the same functional form with a global linear term, a nonlinear term, and region-specific random slope deviations. The analysis uses residuals from the updated Türkiye strong-motion database (SMD- TR), spanning four regions and wide ranges of VS30, magnitude, and distance. Results indicate strong agreement in global behavior: linear and nonlinear terms show similar period trends in both frameworks, and the combined regional slopes are essentially identical at all periods. The overall residual standard deviation is also nearly the same, implying comparable fit quality. Differences primarily concern decomposition and uncertainty representation. The Bayesian model resolves sharper period-dependent regional features—most notably a peak near T ≈ 0.8 s consistent with basin/edge effects—while lmer yields smoother, more conservative deviations. For median predictions, either framework is suitable because the combined coefficients and overall standard deviation coincide. For interpretation and uncertainty propagation—especially when period-dependent regional structure matters—the Bayesian approach is preferable. In addition, brms permits weakly informative priors that encode physical expectations, which stabilizes estimates in data-sparse regimes and helps prevent overfitting. Taken together, these results clarify when each framework is most appropriate: brms for physically constrained inference and robust uncertainty quantification, lmer for speed and simplicity when median predictions are the primary goal

  İncele
• BildiriYalnız künye2026Scopus SJRQ4/r/munzur/1497
  Residual-Based Evaluation of Basin and Basin Edge Effects in Türkiye: Implications for Regional Site Amplification Modeling

  İçen, Abdullah

  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.

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  İncele
• MakaleYalnız künye2026Scopus SJRQ1/r/munzur/921
  Regionalized 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.

  AtıfOpenAlex1

  İncele
• MakaleAçık Erişim2025/r/munzur/6156
  A comprehensive case study on structural behavior before and after soil improvement

  Etli, Serkan; Icen, Abdullah

  Addressing the issue of inadequate engineering properties in soil is crucial for enhancing structural behavior and reducing damages, especially during seismic events. This study addresses the critical issue of inadequate engineering properties in soil and their impact on structural behavior, particularly during seismic events. Employing a case study methodology, structural responses are assessed before and after soil improvement, emphasizing the problem's significance. Site response analyses for pre-improvement phases reveal design insufficiencies and areas prone to soil liquefaction. The proposed solution is soil reinforcement through cement injection. Examining six cases under various earthquake scenarios and ground conditions, 132 dynamic analyses are conducted, highlighting substantial improvements post-soil improvement, especially in Interstory Drift Ratios (IDR) and roof drift ratios. These findings underscore the effectiveness of soil reinforcement in mitigating seismic damage, emphasizing its critical role in enhancing structural behavior and contributing to a better understanding of addressing soil inadequacies for improved seismic performance.

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  AtıfOpenAlex2·TR Dizin2

  İncele
• MakaleAçık Erişim2025Scopus SJRQ2/r/munzur/1316
  A 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.

  AtıfScopus4·WoS3·OpenAlex4

  İncele
• Veri SetiYalnız künye2024Scopus SJRQ1/r/munzur/2204
  An 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.

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  AtıfScopus28·OpenAlex33

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• MakaleAçık Erişim2024Scopus SJRQ1/r/munzur/1748
  Local 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.

  AtıfScopus22·OpenAlex27

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• MakaleYalnız künye2023Scopus SJRQ1/r/munzur/2695
  Region 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.

  AtıfScopus7·WoS7·OpenAlex9

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