Akademik Veri Yönetim Sistemi
18th World Conference on Earthquake Engineering (WCEE2024), Milan, İtalya, 30 Haziran - 05 Temmuz 2024, ss.1-3, (Tam Metin Bildiri)
Vs30, the average S-wave velocity for top 30 m of ground is used for prediction of site effects on
scenario- or event-based seismic intensity maps (Shakemaps), since this parameter is generally used for
estimation of site amplification factors in ground-motion prediction equations, and consequently in
construction of site-specific design spectra in several seismic codes involving that of Turkey. Therefore, the
national 1:500,000-scale digital geological map, and 30 m / 90 m resolution digital elevation data sets are
used for development of estimated-Vs30 map of the county. The uniform database for Vs30 determined through
MASW surveys on sites of the strong-motion stations which are operated by the Disaster and Emergency
Management Presidency of Turkey (AFAD) was used for statistical conclusions. First the geological units are
classified according to the formation descriptions, map details, and the statistical properties of Vs30
distributions. It was concluded that 4 geological classes related to the geological ages can be considered in
estimation of Vs30. Second, the most significant topographical functions to estimate Vs30 was investigated
through the correlation analyses. Consequently, the topographical slope, convexity and texture were
observed to contribute significantly to Vs30 estimations. The optimum grid distance on digital elevation map
for calculation of these topographical functions was estimated by statistical sensitivity analyses. Finally, the
coefficients of empirical functions that are relating these topographical parameters to Vs30 were determined
for 4 classes separately by using the ordinary principle of least-squares. Alternatively, the quantile regression
analyses were used for drawing envelopes of Vs30 pertinent to a given probability of exceedance, including
the probability of 16% being lower, since this corresponds to mean minus one sigma for a Gaussian
distribution presumed in practical applications. Finally, Vs30 maps of Turkey for mean and lower estimations
of Vs30 were produced on GIS. A final discussion on Vs30 estimations for the region severely affected by the
recent Mw7.8 and Mw7.5 February 6th, 2023 Earthquakes in Turkey is presented.