Amplification Maps for Syrian Territory with Respect to Ground Motion Levels and Based on Slope Angle-Velocity Model

In this paper, the ASTER Digital elevation model (DEM) corresponding to ۳۰× ۳۰ m data spacing (medium resolution) is used to produce slope steepness, slope variations in the Syrian territory. The topographic slope corresponding to time-averaged shear wave velocity model (Vs۳۰) developed by Allen and Wald [۱] has been used to derive empirical formula, and then to generate base data of Vs۳۰ map for the Syrian territory. We have found that the values of Vs۳۰ vary between Vs۳۰ ۱۸۰ to ۷۶۰ m/s and fit the geological and topographic setting of Syria. Site-specific amplification factors (Fa and Fv) maps have been estimated with respect to the empirical equations proposed by Borcherdt [۲] . The value of short-period amplification factor Fa varies from ۰.۹۱ to ۱.۸۵, while the value of mid-period Fv lies in the range ۱.۱۶ - ۳.۱۵. Comparing the estimated values of amplification factors for the Syrian territory shows a good similarity to those assigned in IBC-۲۰۰۶ for the same site-class. The acceleration-independent amplification factor F found to be changing from ۱.۳۸ to ۵.۸۳. The reclassified amplification factor F map shows clearly the areas with high potential for amplifying ground motion. The obtained maps are highly required by the Syrian anti-seismic design code. These maps have stored numerically with a resolution of ۳۰× ۳۰ m. The results show that the slope angle-velocity model is an applicable technique for estimating seismic surface shear wave velocity (Vs۳۰ ). Image processing and remote sensing data, as well as digital elevation model can be used successfully to derive amplification maps.

Keywords:

Topographic slope , Time-averaged shear velocity , Amplification factors , Syria