But unfortunately, the solidified crust exists as cracked in to a few pieces which our geo-scientists call as the tectonic plates. These tectonic plates keep moving a few inches every year over the molten liquid rubbing and pressing against each other on the cracked edges, applying great forces. At times, the great rubbing forces cause the plates to make way suddenly, causing the sudden vibrational release of destructive energy a few hundred miles across. That causes some parts of the affected tectonic plate to shake and vibrate for a few seconds. That vibration that is felt over the land and sea is called earth quake.
The vibration has the highest vigor near to the point where the plates rubbed each other. Our scientists call it as the focus point of the quake. Normally, the focus of an earthquake is a few kilometers below the surface. The point directly above the focus on the ground is called the epicentre. Epicentre is a place which is easy for us to identify. The force of vibrations arising out of a quake is measured in terms of a unit called the Richter units using the Richter magnitude scale. When there is no quake vibration, the Richter unit is zero. When it is the highest, its value is 10. It is measured by an instrument called the seismometer or seismograph.
An earth quake of magnitude upto say about Richter 4 are not normally felt by us. Above 5 richter, earthquakes are felt and can cause damage. As the scale goes up, the destructive power also goes up many times.
That is because the Richter scale is logarithmic. The magnitude of a quake which is just one unit more is actually ten times more vigorous. For example, a quake of Richter-5 is ten times forceful than a quake at Richter-4.
When some parts of the tectonic plates shake as a consequence of their destructive mutual rubbing to throw us away as if the irritated elephant shakes its body to throw out its disliked mahout, what could we possibly do to escape from that momentary anger of mother earth?
When it actually shakes with all those megaton energy from underneath, we are indeed helpless. It is only chance and pure luck that you and me come out unhurt from any such episode of natural calamity.
The devastating earthquake that flattened Nepal on the 25th April 2015 forenoon was one such episode!
The time was just approaching 12 Noon and I got the first signs of the tremble. I knew instantaneously that it was an earthquake because I had experienced similar quakes in similar situations in Ranchi a couple of times in the past couple of years.
Just outside, the public school nearby was celebrating some annual event with all the voices of the function beamed out through rented professional loudspeakers as high noises at 150 decibels! That made all other voices and noises at home hardly audible.
Yet I could somehow call my wife doing some moring chores, who obviously had failed to recognize the earth's obvious swings and to make her cautious of the quake which had by now become more obvious. Standing on the floor with the mikes blasting outside, she was unable to recognize the building shaking in slow swings. At first she even argued with me and ridiculed me for my quake imagination.
But then I convinced her to sit on the chair nearby and as she sat down, she too was feeling the swings. The swings by this time had become more obvious as we could watch our flower pots and fans swinging. There were occasional rattlings from the doors and the windows.
We did not get panic as the quake was not felt so powerful for us to jump out. Yet I noticed one thing. The quake was still causing my sofa to swing and it had not yet stopped. Unusually longer duration. It had been shaking for more than a minute now, perhaps almost two. Fortunately, it ended by that time.
We noticed some of our neighbours moving out of their homes as they felt the tremblings of the earth. We wanted to know more about the quake and put on the TV to scan the national channels for getting some information.
In another five minutes or so, the channels became alive with breaking news captions. The tremors have been felt all over north India. But they took some time to pin-point the epicenter and the quake magnitude, apparently because the Indian administrators in an administrative goof-up has made the country's existing earth-quake monitoring facility at IIT-Roorkee dysfunctional. Any way, the media announced the magnitude and epicentre of the quake sometime later. Its magnitude was confirmed at Richter-7.8 and epicentre at some secluded mountaneous village near the capital of Nepal, Kathmandu.
As the days passed, we are learning more and more about the human tragedy unfolding in Nepal from the devastating earthquake of April, 25th. The death toll counts kept rising every day and now it is has become almost countless as it crossed the 10,000 mark. Due to the inadequate infrastructure and administrative system in this part of the world, we may never ever actually know the facts.
While natural calamities are often beyond human managerial abilities when it happens quite unexpectedly, there are a few wise precautions that we could have adopted to mitigate the huge loss of lives and property.
Our geoscientists have found out the regions where the possibility of tectonic activities and earthquake magnitudes are high. Nepal and many areas of North India lie above tectonic fault lines where earthquake possibilities are high.
Earthquakes cause deaths not because it causes direct deaths as in the case of lightnings. Earthquake causes death indirectly. The strong quakes cause unsafe buildings and structures to collapse. The buildings and structures when collapse kill people and entrap people to be killed slowly afterwards.
Buidings that are made of stone and brick masonry work on improvised foundations are the ones that collapse easily in an earth quake. In turn such buildings cause the highest human casualties. Poorly constructed concrete and RCC structures are also equally damaging because they cannot withstand the lateral shaking that earthquakes cause.
Earthquake inflicted damages would be less, if the buildings are of light weight with some flexibility to withstand shaking. Properly engineered pre-fabricated buildings could provide much relief in this context as compared to conventional insitu building construction. Some time ago I had written about the benefits of prefabricated housing as a very viable and affordable housing option.
Pre-fab homes homes and buildings are constructed using light weight, durable and high strength factory made components such as wall panels, modular rooms, cabins, roofing, pre-engineered structurals that could be assembled at site to form large homes and buildings. They are with non-detachable joints that allow lateral shakes and resist collapse. Materials such as steel, aluminium, toughened glass, re-inforced plastics, ferrocement, wood, bamboo and other composites are used for making pre-fab building modules and components.
Prefabricated buildings are comparitively inexpensive and much quicker to construct. For example, this Chinese pre-fab manufacturer has recently completed a 57 storied skyscraper in just 19 days taking full advantage of the prefab building technology.
In the USA, an architect named Angus Macdonald, has developed the patented ferrocement prefab technology now known as the am-cor technology which offers earthquake resistant pre-fab buildings with good aesthetics. Entrepreneurs and investers from India can perhaps negotiate to bring this modern building construction technology to this part of the world.
When the rehabilitation and reconstructions programmes are undertaken, conventional building constrution methods in the earth quake prone areas should be avoided and preference should be given to pre-fab buildings with earthquake safety features.
Let us hope the concerned authorities and people involved in planning such things would use their skills and expertise wisely in the days to come.
At this juncture, let all those of us who are miraculously spared from the disaster, stand united with those unfortunate ones who are facing the tragedy in Nepal and parts of North India.