New Delhi: The new update regarding earthquake risk is directly related to your safety and your home. Bureau of Indian Standards (BIS) has released a new seismic zone map of the country. This change is so big that scientists have put the entire Himalayan region at the highest level of danger. For the first time, ‘Zone-6’ (Zone VI) has been introduced in India. Till now we considered only Zone-5 as the most dangerous. But the new map has shown that the danger is much greater than we thought. BIS has updated the ‘Earthquake Design Code’. Its impact is not only on the mountains but also on the plains and your pocket. This new map is not to scare but to awaken. The energy that is being stored in the Himalayas will come out if not today or tomorrow. We cannot stop earthquakes. But we can strengthen our preparation. The creation of Zone-6 is an indication that now we will have to leave ‘Jugaad’ engineering. Now safety will have to be given first priority while building a house.
Why was Earthquake Jones’ new map brought?
The biggest question is why there was a need to change the map suddenly. Actually the old map was now outdated. It was based on the epicenter and damage survey of old earthquakes. But science has now progressed a lot. Vineet Gehlot, director of Wadia Institute of Himalayan Geology, has explained the reason for this. He said that a large part of the Himalayas has been quiet for the last 200 years. There has been no major earthquake there. This does not mean that the danger has gone away. Rather, it means that terrible energy is accumulating under the ground. This ‘locked energy’ was not estimated correctly in the old map. Therefore, this map has been made using new scientific methods.
BIS released a new map, the entire mountain is now in the most dangerous zone.
Zone-6: Why is the danger so high here?
The biggest change in the new map is regarding the Himalayas. Earlier, some part of the Himalayas was in Zone-4 and some in Zone-5. This division was less scientific and more administrative. But the plates under the ground do not respect boundaries. In the new map, the entire Himalayan Arc has been considered equal. It has been put in the newly created ‘Zone-6’. This zone is the most sensitive. This means that an earthquake with massive destruction can occur here at any time. Scientists say that this classification is based on data and study of fault lines.
61 percent of India is now at risk of earthquake
What is PSHA technique?
The biggest difference between the old and new maps is technology. ‘Probabilistic Seismic Hazard Assessment’ (PSHA) has been used to create the new map. This is an internationally recognized method. In this, only past earthquakes are not considered. In this, data of active fault lines is taken. It is seen what the rocks (lithology) are like under the ground. How earthquake shocks decrease with distance. This technology accurately analyzes the condition of the soil and tectonic plates of every area. This tells us what is the maximum intensity of an earthquake that can occur in the future.
Many important changes have been made in the new seismic zone map. (AI Infographics)
New seismic zone map: What rules for buildings?
- BIS has clearly said that from now on all new buildings constructed will have to follow the 2025 code. The 2016 map will no longer work. This will affect the cost and design of construction.
- The buildings which are near active fault lines. The rules have been made even more strict for them. There the structure will have to be designed keeping in mind the behavior of the ground.
- Engineers will now have to work on ‘site specific response’. That means one rule will not apply for the entire district. Rather, the specific piece of land where the building is to be constructed will be examined.
- A very important change has been made in the new code. It is often seen that a building remains standing during an earthquake. But its parts fall due to which people die. This is called ‘non-structural elements’. Like- water tank, false ceiling, large glass panels, lift and AC fittings.
- According to the new rule, if any heavy item is more than 1 percent of the total weight of the building. So it will have to be anchored in a special way. It will have to be secured through bracing. So that it does not fall and injure anyone during the earthquake. This rule will reduce deaths in moderate earthquakes.
- The new code also has strict instructions for critical infrastructure. Hospitals, schools, big bridges, pipelines and government buildings no longer just have to be made ‘strong’. They also have to be kept ‘functional’. This means that even if a major earthquake occurs, these buildings will continue to function.
It should not happen that the hospital itself collapses during a disaster. Or the supply of electricity and water stops. India is now adopting global best practices. The aim in this is not just to save lives. Rather, it also includes giving immediate response after the disaster.
What will happen to the old houses?
Now the question is about those people whose houses are already built. Do they need to be afraid? The new rules are mainly for new construction. But old houses, especially those in Zone-6 or 5, may need retrofitting. You can get your house checked by a structural engineer. Especially if you live in areas like Himalayan belt or Delhi-NCR. It has now become very important to check the strength of water tanks and balconies.
South India is not in much danger
North India is seeing big changes. There is news of relief for South India. The seismic profile of Peninsular India is almost the same as before. The tectonic plates are more stable there. Therefore, no major changes have been made in the zone there. But even there the rules of non-structural safety will be applicable in new buildings.
