Most of the earthquake codes divide their countries into a few regions and allot basic seismic coefficients to those regions. These basic coefficients are in some cases multiplied by an ad-hoc factor based on the type of soil at site. The depth of soil cover over bed rock generally does not figure in any of these ad-hoc provisions. There have been very little attempts at microzoning of regions. For small regions like that of a city, it may be reasonable to assume the motion at bed rock to remain more or less similar during an carthquake but the ground motion at various location depends on the depth of over burden soil and its properties. Such phenomenon has been observed during actual earthquakes(1).