The structures that are constructed on geologically unstable region where severe or moderately severe earthquakes are experienced and are likely to reoccur, should be de.igned con.idering the dynamic behaviour again.t po •• ible earthquake effect. apart from all other conventional design considerations. In view of the heavy con.truction programme in India, the Indian standard code of practice for Earthquake Resistant Design, based on seismic data obtained from the studies of past Indian earthquakes was fir.t publi.hed in 1962. Through revisions the present revi.ed copy has been made available a. I.S: 1893-1975, Criteria For Earthquake Resistant Design of Structures (Third Revision).