SAHIL KISHORE SHARMA
What really an earthquake means
Earthquake in academic term can be defined as the sudden violent shaking of earth. There are many factors which lead to an earthquake, but main reasons are underground fault developments and volcanic eruptions. As far as Jammu and Kashmir is concerned volcanic history is not found and majority of the earthquakes are caused by the seismic activity at a relative shallow depth, which is caused because the crust of the earth plates generate huge tension when then slides along each other, and with tension a fault is created and the energy is released and we feel the shaking of earth.
How active is Jammu and Kahmir to seismic activities
According to the report of National Institute of Disaster Management (NIDM), Ministry of Training Programme on ‘Earthquake Risk Mitigation and Management, most parts of the Kashmir Valley (11 per cent of the area of the State) covering the Districts of Srinagar, Ganderbal, Baramulla, Kupwara, Bandipora, Budgam, Anantnag, Pulwama, Doda, Ramban, Kishtwar come under Seismic Zone V, where around 50 per cent of the population of the State lives. Rest of the State including whole of Ladakh region and Jammu Division (90 per cent of the total area of the State) are under the Seismic Zone IV. This gives us huge reason to worry. Now let me explain what is Seismic Zone V and IV signify, India is divided in various zones according to the vulnerability to earthquakes and Kashmir has been rated highest, there is one scale which measures the disastrous effect of an earthquake within a given seismic Zone, this scale qualifies zone V as a zone of potentially strong earthquake. And this is a sorry state for us that more than 90 per centof the structures in Jammu and Kashmir are highly vulnerable to earthquakes.
How to make affordable earthquake resistant buildings in your budget:
Affordability of a structure is only significant if it is feasible and good enough to withstand the disaster. Before we think of constructing a building what is prerequisite is to test the soil. To test its bearing capacity. We are habitual of thinking about our budget for the super structure but we forget about the foundation. According to the report on the Earthquakes Trend in India by Colombia University, more than 80 per cent of the buildings collapse because of weak foundation. Foundation is the spine of building, no matter how much we care about the super structure if the foundation is weak it is ought to collapse. So before planning your budget for the building give the maximum attention to foundation because it’s our obsession to make one floor over other and that is where we lack wisdom.
As far as super structure is concerned the day to day materials can be used to make our house earthquake resistant. Though there are very costly methods available in the developed countries for the earthquakes but in a State like ours where having a roof at ones top is considered as a herculean task, making much costly structures will be a challenging task. So the purpose of this article is to give certain techniques to use the available material in the best way to make the structure decently earthquake resistant. Follow these simple steps:
Keep a watch on the amount of water and air in concrete: Though it may sound odd to most of you but water and air are considered the biggest enemy of concrete. No matter how much good finished is your concrete if the amount of water exceeds certain limit it can reduce the strength up to 70 per cent so it means if a building can take the load of 100 people easily just by adding more water in concrete it can now take only up to 30 people. So use water to cement ratio of approximately 0.55. For example, if you require 100kg of cement in your mix, then 100 x 0.55 = 55kg (litters) of water.
Air entrapped in concrete decreases its strength significantly same as water does so use of vibrators should be encouraged, it should be used in beams, columns, slab, lintels where ever concrete is in use, use the vibrators till the air bubbles cease to come. Over vibration also reduces strength so use wisely.
Do proper curing: Curing in simple terms means dipping concrete in water after one day of setting. Curing is a very important phenomenon for the strength of concrete, according to I.S coded 28 days curing is required but one should do curing for at least 14 days if time is less.
Use proper building material: One should remember that cement is only a binding material the real strength is carried by aggregates (Bajri) when we design columns and beams and in a structure where bricks take the load the quality of brick is very important. Use of proper building material and good technique of installation is very important for a structure. Use the materials recommended by Government of India. Reinforcement gives the tensile strength to the concrete and the spacing of bars is the deciding factor for its strength, even when we bind the bars we should take care of it. As far as earthquake is concerned the reinforcement plays more role than concrete, so proper cutting, fitting and installation is required.
What to do at the time of an earthquake:
If you know your structure well it will be easier to make a decision at the time earthquake strikes. Some of the points are shared below:
1Don’t panic because you cannot achieve anything from that. A cool and calm mind works better so keep a control on your nerves.
2.Stand under lintel over doors (Chaukath) because it has less chances to crack or fail.
3.Rush to open space only if it is near, staircases have more chances to fail than your beams, stand under beams. If you are struck in upper floor don’t panic to rush outside, just get under table.
4.Do not stand under the high tension wires or tress. The problem in India is that we have overhead electrification system and the chances of them failing are extreme and it can be catastrophic.
5.If you are living in an unplanned colony where open spaces are less, its better not to rush outside because balconies of the buildings fail first than the beams. Construct buildings with beams and columns avoid load bearing structures there.
One more important thing I would like to share is never get driven away with rumours. Every now and then we hear that someone has predicted an earthquake and gives the deadline for the destruction. All these things are nothing but rumours. There is no instrument in the world which can predict earthquakes and we should remember that earthquake is the problem of world and top minds are working on it but the truth is only earthquake knows when it will strike. We can predict the hazardous areas but no instrument in the world or no supernatural power of the world can predict when, where and of what intensity earthquake can come.
Keeping all these points in mind and implementing them well in our lives we can build a home of our dreams. Where no fear exists and peace prevails. And if all these things are followed religiously we can surely face the earthquake “Head On”.