An earthquake is a phenomenon that occurs without warning and involves violent shaking of the ground and everything over it. It results from the release of accumulated stress of the moving lithospheric or crustal plates.
Vulnerability of India to earthquake related hazards:
- Substantial population living in seismically active Himalayan Zone.
- Limited knowledge of hazards.
- Limited knowledge of impacts on the built environment and society.
- Extensive stock of aged infrastructure, and high retrofit costs.
- Focus of current building codes (only on life safety as opposed to the higher performance standard of limiting damages).
- Decisions not driven by appropriate consideration of risk, often due to inadequate tools and knowledge to determine risks.
- Limited response and recovery capabilities.
- High population increases within or migration to hazardous areas.
- Development and planning actions that are non sustainable in nature.
- Inadequate resources for mitigation actions
Salient features of major disasters caused by earthquakes over last 3 decades:
- 2001 Bhuj: Due to careless building, a previously undetected fault was reactivated, resulting in significant loss of life and property.
- 2004 Indian Ocean Tsunami: Massive waves were generated by under-water seismic activity, flooding coastal towns and islands and triggering long-term impacts.
- 2005 Kashmir: Multiple aftershocks were generated by the 7.6 magnitude earthquake, which was caused by significant upthrust of the Indian plate against the Eurasian plate. Communication and infrastructure were both affected.
The susceptibility of India to numerous seismic risks necessitates careful management and long-term planning.