Akademik Veri Yönetim Sistemi
74.TÜRKİYE JEOLOJİ KURULTAYI, Ankara, Türkiye, 11 - 15 Nisan 2022, ss.1
Various parameters are used for geotechnical characterization and
considering seismic site conditions. Among them, the most widely
used one is the average shear wave velocity (Vs30) of the first 30
meters of the Earth's surface. Within the scope of the study, Vs30
measurements of accelerometer stations which are operated by the
Disaster and Emergency Management Presidency (AFAD)
throughout Turkey, were mapped, and the slope and elevation values
of these points were calculated using high resolution digital elevation
models. In addition, the geological units and the morphological
terrain classes in which the stations are located were determined, and
their correlations with the measured Vs30 values were examined. As
expected, the Vs30 values were found sensitive to slope,
morphology, and geology, while the sensitivity to elevation was
weak.
Two different Vs30 prediction models were examined for
performance analysis. The predictions of the global Vs30 model of
the United States Geological Survey (USGS), which is based on the
topographic slope for different soil classes, differ from the
measurements in Turkey, especially in low-slope regions. On the
other hand, the Vs30 prediction model based on the available
borehole and geophysical data throughout Italy which includes
different factors such as lithology, slope, morphological land classes,
and elevation, resulted in generally higher Vs30 values than the
measured ones across Turkey.
Performance analysis results showed that current Vs30 prediction
models across Turkey are especially less consistent in younger units
characterized by low Vs30 values. This implies that a more detailed
characterization of young lithologic units is needed for Vs30
prediction. In this study, classification of young units on the basis of
water saturation level was established using spatial factors, and new
Vs30 prediction models were developed. This approach better
reflects the divergent Vs30 values observed in younger units.