Influence of Engineering Rock Properties and Historical Ground Shaking Indicators on Seismic Microzonation of India

Earthquake occurrence is a natural phenomenon on which man has no control. Local geology significantly alters the amplitude and frequency content of earthquake ground motion. In particular, the physical properties of rock, such as shear-wave velocity, density and compressive strength exert major control on the degree of amplification or the attenuation experienced by travelling waves. An example of this is the soil liquefaction observed in 1934 Bihar and 2001 Bhuj earthquakes. The current study deals with data compilation and analysis with respect to physical and mechanical properties of rocks. Shear wave velocity, rock density, UCS, bearing capacity, foundation compatibility, lineament density, frequency of earthquake events are few parameters analyzed to get the Rock Seismicity Index which is different for various rocks. The Seismic Risk Index (SRI) is generated based on rock seismicity index and the historical ground shaking indicators in the form of isoseismals. The complex dataset in various layer formats is superimposed in Geographical Information System (GIS) to get seismic zoning of India with respect to rock seismicity. The map thus generated is a fair representation of rock seismicity across India, and this map can very well be used by Engineers as guideline for the structural and foundation designing.