The truth is that they can happen any time. But we are not certain when they will hit. There is no reliable way to predict the earth quakes. So there is no point to unnecessary panic. We should control what we can. Not thinking much about the uncontrollable. It is well known historically and scientifically that J&K is prone to earth quakes. As most of its regions lie in seismic zone iv and v. The J&K UT is situated near the boundary of tectonic plates, which makes it susceptible for an earth quake. It is being said that the Radon gas could be an indicator of earth quake. If the concentration of Radon gas increases in the atmosphere or soil or in the groundwater. Then they are chances of earth quake occurrence in the area. Lately, numerous mild tremors were felt in the Chenab valley. Many people have apprehensions that the construction of dams across the Chenab valley could be the reason behind the tremors. Does that make sense? First we must know what an earth quake is? The earth quake is shaking of the earth’s surface due to a slip on the fault and results in release of seismic energy or due a volcanic eruption or magmatic activity or other stress changes in the earth’s surface’s we can say that any shaking of the earth could be termed as earth quake. Mostly we are concerned with earth quakes which occur due to a slip on the fault along the plate boundaries, commonly called tectonic earth quakes. Now coming to our question, could dams cause earth quake? The answer in the simplest of the terms is Yes. But for dams to cause earth quake the area should already be geologically weak and the dam must be constructed near the fault lines or in the area where fault lines are present. There is no way to predict even when the dam would induce an earth quake. Such earth quakes are termed are reservoir induced seismicity (RIS). The Konya dam is said to be an example of RIS, where the earth quake of 6.5 magnitudes on ritcher scale occurred three years after the dam was constructed, killing 180 people. The RIS is though not fully understood. When the dam is constructed and reservoirs are filled with the water, the stress on the earth in that area changes.
The filling up of the reservoir with water increases the pressure on the rocks beneath and lowering the level of the water in the reservoir would decrease the pressure on the underlying rocks. The fluctuation of the pressure on the underlying rocks, could result in disrupting the delicate balance between the tectonic plates which could make them shift, causing earth quakes. The increase in water pressure would force the water to move downwards, sometimes resulting in further widening up of the cracks or faults in the rocks or could create new tiny cracks altogether. The result would be enhanced instability of the rocks beneath; causing earth quakes. The water moving deeper could as a lubricant for the rock plates that are being held together by friction alone. The lubrication would make the plates slip. These things could happen. But when the earth quake hits, it is not possible to say beyond doubt that the culprit was the dam. So not constructing dams in seismic zones areas would be better. Though as of now, there is no certainty that the dams are a reason behind the earth quakes. They could be. What we are sure though is that the dam collapse is more likely to occur in earth quake prone areas. As the shaking of the earth could result in the failure of the dam. This could cause immense loss of life and property. The dams saturate the soil beneath it, there are chances of great landslides in areas where dams are built. So, as far as possible the dam construction should not be undertaken in earth quake prone areas. The reality is that the dams are a must for the energy generation. If we are to construct a dam, we must ensure that at least only small dams are built. As the hazards of small dams are less. Build many small dams, instead of one large dam. That would be somewhat safer. Small dams are more eco-friendly than the larger ones. The large dam construction should be stopped altogether. The panic could get us killed. We should learn to live with the earth quakes or any other disaster. We should ensure that our buildings are earth quake resilient. That means we should follow the building codes of seismic zone areas. There should be mock drills related to earth quake. The Dos and Don’ts must be strictly followed, in case earth quake hits the area. The preparedness before the disaster would save us during the disaster.
(The author is a lecturer at Govt Degree College Kargil Sankoo. Views are his own)