Reliable assessment of seismic risk in a region requires knowledge and understanding of
both seismicity and attenuation of strong seismic ground motion. In India strong ground
motion records are almost non-existent. In recent years, some strong motion instruments
have been deployed in the seismically active regions of the Himalaya. The high seismicity
of the Himalayan region is attributed to the collision of Indian and Eurasian plates in the
geological past. Presently, Indian plate is subducting beneath the Eurasian plate at a rate
of 4-5 cm per year. Due to the motion of Indian plate, the collision boundary is seismically
very active. The whole region has experienced many major earthquakes in this century. For
the protection of life and property from earthquakes, it is essential to have an idea of seismic
risk in the region. The seismic risk in a region can be assessed using attenuation of  strong
ground motion. In the absence of abundant strong ground motion data, empirical relations
relating different measures of ground motion with earthquake parameters can be used to
predict the level of ground motion in future earthquakes. The design of important structures
such as nuclear power plants, dams and high-rise buildings uses estimates of ground motion.
In the present work, we have made an effort to develop some attenuation relationships to
calculate attenuation of strong ground motion in different Indian regions based on the past
earthquake data. Attenuation relations have been developed for peak horizontal acceleration
and peak velocity for different regions. We have also studied the intensity attenuation for
different earthquakes of India, and similarity between the intensity attenuation and the ground
motion attenuation is discussed. The ground motion relations for different regions of India
have been compared with those of other geographical regions in the world. The attenuation
relations derived in this work are proposed for use in a variety of Earthquake Engineering
applications and in the preparation o seismic zoning map.