An Overview of Seismic Zonation Studies in India Mohapatra, A.K. Mohanty, W.K. Research Scholar Associate Professor e-mail: alokgpiitkgp@gmail.com e-mail: wkmohanty@gg.iitkgp.ernet.in Department of Geology and Geophysics, IIT, Kharagpur, Kharagpur ABSTRACT The paper discusses a brief history of seismic zoning studies in India through chronological order including the limitations on its use. It also discusses the progressive development of the seismic zonation map of India and how it was reviewed, revised and modified periodically with the availability of more data and with a better understanding of the dynamics of the earthquake. Seismic zoning is one such step for assessing the hazard in a country and provides input parameters to planers and civil engineers for safe designs and construction of structures, which can sustain due to an earthquake. The Seismic Zonation Map of a country is not only guides about the seismic status and susceptibility of a region, but also indicates the direction of future work. Such observations also point out that there is a clear-cut and urgent need to focus research and development, public awareness, geo-technical competence, enforcement on engineering aspects for earthquakes in India. Indian Geotechnical Conference – 2010, GEOtrendz December 16–18, 2010 IGS Mumbai Chapter & IIT Bombay 1. INTRODUCTION In the last decade, the Indian subcontinent has experienced many devastating earthquakes. The occurrence of earthquakes is not evenly distributed in India. Major earthquakes of India are associated with the collision plate boundary between the Indian and Eurasian plate. The occurrence of earthquake is irregular in the southern India, whereas the northeastern, the northern and the northwestern part of India are subjected to regular earthquakes. The Himalayan Frontier is seismically one of the most active regions of the world. The peninsular India is also not devoid of earthquake. It was recently significant for three severe earthquakes such as Killari in 1993, Jabalpur in 1997 and Bhuj in 2001. As per the UN report the damage and human loss due to earthquake in developing countries like India is quite high compared to the developed nations. The regular occurrence of earthquakes reminds us about the high level of seismic hazard and risk prevailing in the country. There is a dire need to integrate all the recent advances in our knowledge to produce the state of the art zoning map, both on large as well as micro scales on which the public can depend. Seismogenic zones were classified on the basis of historical seismicity, geology, tectonics, soil types, and seismo-tectonics intensity of ground motion. This review article discusses a brief history of seismic zoning studies in India through chronological order. We discuss the scope for future studies to prepare more realistic seismic zoning maps for India. As there is a wide variation in the intensity of ground motion and also in the frequency of occurrence of earthquakes, there was a need to divide India into broad zones in terms of expected ground motion to represent the seismic hazards. Besides the zoning map of India by the BIS, other non-official seismic hazard map have been available in literature by various workers (Auden, 1959; Guha, 1962; Kaila & Rao, 1979; Khattri et al., 1984; Bhatia et al., 1999 and Parvez et al., 2003;) based on the statistical or probabilistic models. 2. WHAT IS SEISMIC ZONING? Seismic Zoning can be defined as a process by which areas are subdivided into seismic zones based on expected of ground motion, which is expressed in terms of peak horizontal ground acceleration (PGA) or peak ground velocity (PGV). On the other way, seismic Zonation demarcates equal hazard with respect to a characteristic of strong ground shaking and of site or structural response. A seismic zoning map differs from seismicity map by the fact that it specifies the levels of force or ground motions for earthquake resistance design, where as seismicity map provides location and characteristics of earthquakes. 3. WHY SEISMIC ZONATION IS NECESSARY IN INDIA? Seismic zonation is a process, which provided information about any decision making for urban regional planning or for