Yoğun kentsel ağlarda kaydedilen kuvvetli yer hareketi verilerine göre azalım ilişkilerinin yerelleştirilmesi

The regional dependency of ground motions underlines the necessity of adopting a more localized approach in the estimation of ground motion parameters (GMPs). This thesis kicks off with a consistency assessment of the five most suitable regional or global ground motion prediction equations (GMPEs) for the interested area and our local database including 6,534 individual horizontal-component ground motions recorded by the İstanbul Earthquake Rapid Response and Early Warning System (IERREWS) network during 78 small-to-moderate earthquakes. The examination uncovers a systematic overestimation tendency in GMPEs. Using the same database, an analysis is conducted to ascertain whether there are any regional azimuth-dependent effects on ground motions. Due to the vagueness of azimuthal effects, the ground motion recording axes are converted to their principal axes, indirectly introducing the azimuthal influence into the analyses. This thesis suggests a station-specific methodology to refine GMP estimations by isolating regional variations. Evaluation of regression outcomes, distance scalings, and residuals guide the selection of the most appropriate functional forms for the empirical equation. Comparisons of the spatial distribution of peak ground acceleration (PGA) for hypothetical and actual earthquakes serve as the basis for the evaluation of the result consistency. Local variations between GMPEs' estimates and station-specific approximations provide insight into the impact of regional effects on ground motions. The assertion is substantiated by the finding that PGAs calculated from actual earthquake records demonstrate a closer match with station-specific methodology's predictions, especially in regions with observed local differences.