In the last three decades, large earthquakes have caused massive loss of lives and extensive physical destruction throughout the world (Armenia, 1988; Iran, 1990; US, 1994; Japan, 1995; Turkey, 1999; Taiwan, 1999, India 2001, Sumatra 2004, Pakistan, 2005). India has been facing threat from earthquakes since ancient times. In India, the recent destructive earthquakes are Killari (1993) Jabalpur (1997) Bhuj (2001) Sumatra (2004) and Indo-Pakistan (2005). Seismic activity of India is evident from these recent earthquakes within the intra plate and along the boundaries of Indo-Australian Plate and Eurasian Plate. Many researchers address the intra plate earthquakes and seismicity of South India (Purnachandra Rao, 1999; Ramalingeswara Rao, 2000; Sitharam and Sreevalsa, 2012; Iyengar and Raghukanth, 2004). Many earthquakes in the past have left many lessons to be learned which are very essential to plan infrastructure and even to mitigate such calamities in future.

The hazards associated with earthquakes are referred to as seismic hazards. The practice of earthquake engineering involves the identification and mitigation of seismic hazards. Study of seismic hazard and preparation of microzonation maps will provide an effective solution for city planning and earthquake resistant design of structures in an area. Seismic hazard is the study of expected earthquake ground motions at any point on the earth. Microzonation has generally been recognized as the most accepted tool in seismic hazard assessment and risk evaluation and it is defined as the zonation with respect to ground motion characteristics taking into account source and site conditions [TC4-ISSMGE, 1999]. The earthquake damage basically depends on three groups of factors: earthquake source and path characteristics, local geological and geotechnical site conditions, structural design and construction features. Seismic microzonation is the initial phase of earthquake risk mitigation and requires multidisciplinary approach with major contributions from geology, seismology and geotechnical engineering. Making improvements on the conventional macrozonation maps and regional hazard maps, microzonation of a region generates detailed maps that predict the hazard at much smaller scales. Seismic microzonation is the generic name for subdividing a region into individual areas having different potentials hazardous earthquake effects, defining their specific seismic behavior for engineering design and land-use planning.

The basis of microzonation is to model the rupture mechanism at the source of an earthquake, evaluate the propagation of waves through the earth to the top of bed rock, determine the effect of local soil profile and thus develop a hazard map indicating the vulnerability of the area to potential seismic hazard. Seismic microzonation will also help in designing buried lifelines such as tunnels, water and sewage lines, gas and oil lines, and power and communication lines. Very preliminary process of reducing the effects of earthquake is by assessing the hazard itself. As part of the national level microzonation programme, Department of Science and Technology, Govt. of India has initiated microzonation of 63 cities in India (Bansal and Vandana, 2007). Some of them are finished and some of them are ongoing. As an initial experiment, seismic hazard analysis and microzonation was taken up for Jabalpur city in Madhaya Pradesh. Further, for many other cities such as Sikkim, Mumbai, Delhi, North East India, Gauwhati, Ahmedabad, Bhuj, Dehradun and Chennai an attempt has been made to carryout microzonation considering geomorphological features and detailed geotechnical studies. Among the above Jabalpur, Sikkim, Gauwhati and Bangalore microzonation works have been completed. However, for Sikkim and Gauwhati, microzonation reports are already available and the report on microzonation of Bangalore is in the final stages which will be released within few months.

In this presentation the state-of-art practices of microzonation along with brief summary of the Indian experiments will be discussed along with details of earthquakes in India and the steps taken for disaster management in India with respect to earthquakes. Important issues related to seismic microzonation of Indian cities with reference to seismology, Grade and geological details, and geotechnical details are highlighted. For shallow overburden regions (region having engineering rock within 30m) application of 30m average site class may not be appropriate. Such regions it is recommended to take average shear wave velocity of overburden thickness (up to the engineering rock depth). Probabilistic hazard map for particular return period will be more useful for vulnerability and risk analysis.