During an earthquake, a building experiences two types of seismic forces : lateral and uplift. Lateral or shear forces are horizontal forces which cause back and forth movements Uplift forces are vertical forces which cause up and down movements. Using metal connectors, shear walls & fasteners strengthened the structural stability of the buildings. Retrofitting is the process of reinforcing the foundation of existing buildings to bring them at par with present norms of earthquake resistance.
The earthquake disasters can be averted with the construction of seismic proof buildings. Each building can be designed in such a way that it may withstand during severest quakes depending on the seismic zone it falls in. The multistoried structures are considered at a higher risk due to gravitational pull. A single storey or a multi-storied building may be equally prone to an earthquake but the fact is that a poorly designed single structure may crumble, while a well-designed multi-storey structure may only shake,”The National Disaster Management Authority (NDMA) has made it compulsory for all new constructions to be earthquake-resistant, especially in cities located in seismic zones. The guidelines have also recommended selective seismic strengthening and retrofitting of existing priority structures located in high-risk areas.
The buildings retrofitted to withstand earthquakes survive better than those that have not been upgraded. Even simple efforts, such as bracing parapets, tying buildings to foundations, and anchoring brick walls at the highest, or roof level, have been proved extremely effective to protect buildings during earthquake. . It has also been proven that well maintained buildings have faired better than those in poor condition during and after an earthquake. Thus, maintenance and seismic retrofit are two critical components for the protection of historic buildings in areas of seismic activity. It makes no sense to retrofit a building without improvements. The subcontinent is sitting on the highly seismic Indian plate, with some major faults lines. In fact there is no seismically safe zone in India. Disasters have left the 800-year-old Qutub Minar with a slight tilt but it has survived several quakes in its lifetime.
1. Implementation of Disaster Management Plan :-
The Disaster Management Bill, likely to be presented in the winter session of Parliament, will make it necessary for all states to have a disaster management authority and implement the national disaster plan. "Eventually disaster management is a state’s concern and the action plan has ultimately depend upon the state’s own concerns and ability to set up institutional and financial
2. Creation of Special Force At National Level :- At the national level, other measures are being planned. Eight battalions of 10,000 soldiers are being trained for being posted to eight different locations and money has also been sanctioned for buying aircraft for their use in cases of emergency.
3. Creation of Emergency Operation Centre :- is being equipped with state-of-the-art communication links and micro-zonation of 38 cities above 10-lakh population is being attempted in different phases. The micro-zonation of Delhi has just been completed.
In words of Science and Technology Minister Kapil Sibal, the micro-zonation process is the government’s effort to take effective measures with proper research to minimise risk to existing buildings in the event of an earthquake. Micro-zonation, he says, will help bring area-wise changes in building bylaws to ensure quake resistant measures in the structural designs of high rises to minimise the risk of heavy damage and loss of life in event of an earthquake.
While the government is attempting a paradigm shift in the disaster management from relief and rehabilitation to mitigation and prevention, to make it successful will eventually depend upon the civil society.
Retd. Senior Town Planner of