Chennai: Despite being hit by the second highest G-forces (gravitational forces) ever recorded, the buildings of Christchurch withstood the earthquake, says professor David G.Wareham, Associate Dean (international), University of Canterbury, New Zealand. He said India should invest more money on safe buildings to prevent loss of lives in the event of earthquakes.
A wastewater treatment specialist, he delivered a lecture on the effects of earthquakes on waste water, treatment plant and sewage disposal problem in the city on Monday.
He interacted with Deccan Chronicle on his study of how the city of Christchurch in New Zealand responded to the disastrous earthquakes in 2010 -11 and lessons for India from that experience.
Excerpts:-
Earthquakes cannot be prevented. The earthquake recorded in Christchurch is the second highest G-forces that ever recorded. It’s like the buildings jumped off their foundations. Yet our buildings withstood the forces because the buildings have been designed for the quakes. Considering the force of quakes we have lost only 185 people which was very, very low.
We had 13,000 aftershocks after the quake. We have done so much earthquake prevention in our buildings they did behave very well. Yet, we had to bring down many buildings as they were damaged.
In our case, there was an immediate need for sanitation and how quickly we solve that will ultimately be decided on how quickly the city can move forward. If your city does not solve the immediate sanitation problem, it will delay how much you can recover.
Chemical toilets: For areas affected by sanitation system they provided chemical toilets. About 38,000 chemical toilets were distributed. Around 3,000 portable toilets also have been distributed.
You can drive around trucks and distribute water very easily. But if you don’t take care of sanitation then immediately diseases will spread rapidly.
I would say probably after six months of the earthquake we had about 50 per cent of wastewater treatment system restored. By two years later, we had about 90% capacity. It’s a staged progress and recovered well.
Rebuilding of Christchurch: As far as the rebuilding of the city is concerned, we are about the halfway there. We are currently spending Rs 500 crore per week which comes around Rs.25,000 crore per year. The spending will go on for another two-three years. Then it will come down. We will probably finish the buildings in 10 years.
The earthquake has severely damaged the eastern side of the city and on the western side, the damage was less. Land was also damaged on eastern side, so it’s not worth rebuilding there. It will be like building on sand. They are turning eastern side as the parks.
Lessons for India: In India it is different. Your earthquake risk is distributed across the lands. North India is prone to earthquakes and Chennai is less prone to the quakes.
You should be investing money in safe buildings in north India. Since Chennai is a low seismic zone the major risk would be Tsunami waves coming into the city. You have to create early warning signals and deploy warning systems so that people can get out of danger zones.
To meet the Chennai floods like situations you have to implement redundancy in your systems. You have to estimate flood levels and raise your buildings and critical infrastructure above that level. Second, you need to have a disaster preparedness plan.
