SEISMIC SOIL MICROZONATION IN TURKEY: BRIDGING GAPS BETWEEN INTERNATIONAL STANDARDS AND LOCAL IMPLEMENTATION

Abstract

Seismicity and geological settings of Turkey are very active and complex, where advanced techniques have to be implemented to mitigate seismic risks through techniques such as soil microzonation. The present study critically reviews the soil microzonation practice under the provisions of the Turkish earthquake code (TEC) and the implementation problems, such as inconsistent geotechnical data, insufficient local capacity, and enforcement gaps in regulations. The study highlights ort similarities and differences in the classification of soils, site-specific ground motion analyses, and geotechnical hazards assessments (e.g., liquefaction, landslides) by comparing Turkey against international practices such as Eurocode (EU), Japanese, American (NEHRP/ASCE/IBC), and Chinese (GB). The methodology puts important emphasis on detailed investigations of the site, including drilling boreholes, conducting in situ tests (SPT, CPT), and geophysical survey (MASW) to derive seismic microzonation maps as a reliable means. These maps provide assessments of shear wave velocity, amplification potential, and liquefaction susceptibility—information essential for seismic design and urban planning. Comparative results show that while site-specific assessments and Vs-based soil classification are common to all standards, they differ in their regulatory frameworks and treatment of hazards and in the rigor applied to their implementation. Findings support the ort h of embracing the best practices of the global standards in order to enhance the Turkish soil microzonation, which will lead to safer construction practices and urban development resilient to earthquakes.

Keywords

• Soil Microzonation
• Turkish Earthquake Code (TEC)
• Site Effects
• Seismic Risk Assessment; Geotechnical Investigation.

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