Seismic Microzonation of Indian Cities and Strategy for Safer Design of Structures

Abstract

AbstractResiliency to structures during earthquake shaking is extremely important for cities that are associated with earthquake source zones or located in the vicinity of earthquake prone belts. Present state of knowledge does not allow us to predict the occurrence of earthquakes with respect to location, time, and size of the earthquake. Here, we made an attempt to address the issues involved with earthquake risk resiliency to structures in the light of availability of GIS-based comprehensive seismic microzonation maps, comprising of multi-thematic maps pertaining to se-smological, geophysical, and geotechnical characteristics of the sub-surface formation on 1:10,000 and 1:25,000 scales for many Indian cities. This becomes very important since diagnostic earthquake precursors and earthquake early warning system for the earthquake prone-regions are not yet feasible till date. Successful case studies for some of Indian cities (Delhi-NCR, Bengaluru, Guwahati, Kolkata, Jabalpur, and entire Sikkim state) aptly demonstrated the efficacy of different thematic maps that are generated through seismic microzoning areas under investigations, which can be used by civil engineers and city planners during construction of safer dwelling and infrastructures. Here, we present a detailed discussion about seismic macro-hazard zonation vis-a-vis the seismic microzonation with reference to the evaluation of several geotechnical parameters to highlight the importance of adoption of seismic microzonation program as an earthquake risk mitigation strategy which can help in promoting the construction of earthquake risk resilient structures. Extended form of the methodology of seismic microzonation of a region with finer details along with a way forward for its diverse applications has been discussed here. We have also provided a cyclic seismic risk resilient strategy for sustainable development of infrastructures for safer urban agglomerates through land use planning that may help in taking seismic risk mitigation decisions.KeywordsRisk resilient structuresSeismic microzonationSite responseSite vulnerabilityGeotechnical parametersSeismic risk mitigation decision