Seismic Site Characterization in Delhi Region using Multi channel Analysis of Shear wave Velocity (MASW) Testing Dr D Neelima Satyam Associate Professor, Department of Civil Engineering VNR VJIET, Hyderabad, India neelima.satyam@gmail.com Dr K S Rao Professor, Department of Civil Engineering Indian Institute of Technology Delhi, New Delhi, India raok@civil.iitd.ernet.in ABSTRACT After the Bhuj earthquake the national capital region of Delhi attracted major attention of several scientific studies in the recent times. Since Delhi falls in zone IV (IS 1893:2002) with high seismic activity, there is a great need for site characterization and seismic hazard mapping of the area. Multi Channel Analysis of Surface Wave (MASW) tests were done in Delhi at 118 sites in predefined grids of 2kmX3km each. Shear-wave velocity, V S , is an important parameter for evaluating dynamic behavior of soil. This test carried outdone using 48 channel digital engineering seismograph with 4.5 Hz geophones. Data was analyzed using SeisImager/SW software and two dimensional shear wave velocity models at every 5m depth from ground surface was developed. Also, the average shear wave velocity up to 30m (V S30 ) is measured which is used for site characterization. Based on the Vs 30 value, Delhi is divided into three zones i.e., zone A (V S30 >350m/s), zone B (V S30 = 250-350m/s) and zone C (V S30 < 250m/s). KEYWORDS: Shear wave velocity, Multi channel Analysis of Shear Wave, Site Characterization. I NTRODUCTI ON Geophysical tests based on the generation and propagation of seismic waves are widely used in Earthquake Geotechnical Engineering. Seismic in-situ tests are often the only way to determine soil stiffness in undisturbed conditions, especially for coarse soils, in which undisturbed sampling is problematic. The shear modulus can easily be derived if the velocity of propagation of shear waves and the soil density are known. The shear wave disturbances, as they travel through the soil media, map out dilational and rotational strains. Hence, Vs is currently used as one of the important factors in site characterization. Shear wave velocity structure could be ascertained through invasive