Figure showing areas taken up and to be taken up for Microzonation by ISR.


  • To determine maximum possible acceleration at different locations in an area for different natural periods of buildings, i.e. Response Spectra on the ground.

STEPS FOR SEISMIC MICROZONATION 1. Determination of acceleration at base rock

  • Estimate acceleration due to past earthquakes for return periods of 475 yrs or 2475 years. Probabilistic method takes into account the past Seismicity and gives expected Peak Ground Acceleration (PGA) at base rock the 10% probability exceedes in 50 years and 2% probability of exceedes in 50 years.
  • Deterministic method gives acceleration for different natural periods of buildings expected from the nearest possible large earthquake along the existing geological faults at base rock..

Estimation of amplification due to soil

Peak Ground Acceleration and special Acceleration for different heights of buildings at ground surface.