Seismic Site Characterization in Delhi Region using Multi channel Analysis of Shear wave Velocity (MASW) Testing

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, VS, 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 (VS30) is measured which is used for site characterization. Based on the Vs30 value, Delhi is divided into three zones i.e., zone A (VS30>350m/s), zone B (VS30 = 250-350m/s) and zone C (VS30< 250m/s)