Application of Interpolation Methods for Peak Ground Acceleration Estimation in Emergency Management of Metropolises

Various interpolation techniques are applied to the data from 35 acceleration stations covered Tehran City, the capital of Iran. Data of Firozabad-Kojour (2004) and Kahak-Qom (2007) earthquakes, which recently occurred near to the Tehran City, were analyzed here. The accuracy of estimated PGA using different interpolation techniques is examined by comparing estimated and recorded PGAs at the test sites which are excluded from interpolation analysis. Furthermore, the interpolation at depth (on engineering bedrock) is also investigated by transferring the surface time histories to the depth using available geotechnical and geophysical information at the sites. Then, the PGAs at depth were interpolated beneath the test stations and multiplied to the amplification factors averaged over period ranges of 0.1 to 0.5 s using representative amplification functions for each site category given in previous study by Ghayamghamian and Nojavan (2008). This provides better estimation for PGA even with respect to surface interpolations.