Soil classification based on empirical earthquake data analysis in Tehran

Recently three major earthquake occurred near Tehran Megacity that provided high qualitydata recorded by Iranian Strong Motion Network (ISMN). These data provide a uniqueopportunity to evaluate site effects and to classify local soil conditions based on soil dominantfrequency in Tehran and neighboring area. The horizontal-to-vertical spectral ratio (HVSR)and soil to reference site spectral ratio (SR) of S-wave part of recorded motions was used toestimate the soil amplification characteristic at the sites. The soil classification scheme basedon dominant frequency given by previous studies by second author are used to classify thelocal soil conditions to four categories from hard to loose (I to IV). So, the local soilconditions at the recorded stations of strong ground motions are classified based on dominantfrequency identified from HVSR and SR ratios. Furthermore, the defined soil classes werecompared with those inferred from geotechnical analysis, which revel good conformity givenmore confirmation to identified results.

Keywords:

HVSR , SR , empirical analysis , local site effects , soil classification , Tehran city