THE PRODUCTION OF ESTIMATED-VS30 MAPS FOR TURKIYE ON GIS BY USING THE GEOLOGICAL AND ELEVATION MAPS

Date

2024-06-30

Author

Yılmaz, Mustafa Tolga
Koçkar, Mustafa Kerem
Temiz, Ahmet
Gökalp, Kıvanç
Şahin, Gökhan
Jalehforouzan, Amir
Akgün, Haluk
Askan Gündoğan, Ayşegül
Erberik, Murat Altuğ

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Vs30, the average S-wave velocity for top 30 m of ground is used for prediction of site effects onscenario- or event-based seismic intensity maps (Shakemaps), since this parameter is generally used forestimation of site amplification factors in ground-motion prediction equations, and consequently inconstruction of site-specific design spectra in several seismic codes involving that of Turkey. Therefore, thenational 1:500,000-scale digital geological map, and 30 m / 90 m resolution digital elevation data sets areused for development of estimated-Vs30 map of the county. The uniform database for Vs30 determined throughMASW surveys on sites of the strong-motion stations which are operated by the Disaster and EmergencyManagement Presidency of Turkey (AFAD) was used for statistical conclusions. First the geological units areclassified according to the formation descriptions, map details, and the statistical properties of Vs30distributions. It was concluded that 4 geological classes related to the geological ages can be considered inestimation of Vs30. Second, the most significant topographical functions to estimate Vs30 was investigatedthrough the correlation analyses. Consequently, the topographical slope, convexity and texture wereobserved to contribute significantly to Vs30 estimations. The optimum grid distance on digital elevation mapfor calculation of these topographical functions was estimated by statistical sensitivity analyses. Finally, thecoefficients of empirical functions that are relating these topographical parameters to Vs30 were determinedfor 4 classes separately by using the ordinary principle of least-squares. Alternatively, the quantile regressionanalyses were used for drawing envelopes of Vs30 pertinent to a given probability of exceedance, includingthe probability of 16% being lower, since this corresponds to mean minus one sigma for a Gaussiandistribution presumed in practical applications. Finally, Vs30 maps of Turkey for mean and lower estimationsof Vs30 were produced on GIS. A final discussion on Vs30 estimations for the region severely affected by therecent Mw7.8 and Mw7.5 February 6th, 2023 Earthquakes in Turkey is presented.

URI

https://hdl.handle.net/11511/117930

Collections

Department of Civil Engineering, Conference / Seminar