Seismically speaking, Northeast India is one of the most active regions of the world. Two large earthquakes in the recent past, one in the Shillong Plateau in the year 1897 and the other on the Assam-Tibet border in 1950 have been strong indicators of this.
There are people in the region who still have fresh memories of the 1950 earthquake which, like the 1897 earthquake, had struck with a Richter Scale magnitude of 8.7. The District website of Dhemaji holds the Great Earthquake of 1950 responsible for the regular annual floods even today, stating that the earthquake left the entire riverine system of the area severely disturbed.
According to the United States Geological Survey (USGS), the 1950 earthquake wiped off around 70 villages in the Abor Hills, mostly by landslide activity which further led to the blocking of the Subansiri River. This natural dam so created, notes the USGS, broke 8 days after the ill-fated day, creating a wave 7 m (23 ft) high which inundated several other villages and killed 536 people. The quake was felt in Lhasa and in Kolkata and seismic seiches were observed in many lakes of Norway and in at least 3 reservoirs in England.
Recent studies in the last two decades, and micro-earthquake surveys in the Shillong Plateau and adjoining areas have revealed a high level of seismicity, indicating that the Plateau is under compressional stress. What is worrisome is that several scientists have been suggesting that northeast India is now due for a large earthquake. Moderate intensity earthquakes have been striking the region of late, the most recent incident being last month in Meghalaya’s Garo region.
Fortunately, the Government has taken note of this and in a meeting with a member of the NE Council last week, we were glad to learn that disaster preparedness plans are being formulated, training exercises being carried out across the region, top-level disaster management workshops have already taken place in all states except Nagaland and Manipur and geological studies are being undertaken right now.
All this, in an attempt to be ready for any forewarning–to catch even one small sign–any early warning of the impending earthquake which can then help issue early warning, and take necessary action to save precious lives.
However and very surprisingly, the same Government is working to install big dams in the same region, almost simultaneously. If even for one moment, we forget all the other destructive impacts big dam construction has on local people and environments, the seismic status of the Northeast region should be reason enough for any government, at state or Center, to not even think of such a suicidal ‘development project’.
Any mega dam in the region, will be a time bomb that will tick all the way to imminent destruction. Instead of discussing, let alone constructing, mega dams in the Northeast region, the Government of India should right now be vigilant in ensuring no big dam is constructed by China in the upstream of any river that flows into India.
Reservoir Induced Seismicity (RIS): Recent scientific investigation has revealed that Earthquakes can be induced by dams. To quote from International Rivers, “The most widely accepted explanation of how dams cause earthquakes is related to the extra water pressure created in the micro-cracks and fissures in the ground under and near a reservoir.
When the pressure of the water in the rocks increases, it acts to lubricate faults which are already under tectonic strain, but are prevented from slipping by the friction of the rock surfaces.” Though popular literature refuted the claim, scientific evidenced replies and more popular literature has confirmed that dams really can trigger earthquakes.
Thus, keeping this in mind, and recalling all the other impacts of big dams, constructing such structures in the otherwise very fragile ecosystem of Northeast India, which is already struggling to preserve its rich cultural diversity in the face of the “modernisation” wave, should actually be considered an act against the State and its people. Fortunately, we have a very active Environment Ministry (MoEF), led by an even more active Environment & Forest Minister Jairam Ramesh who has a thinking cap on, and has exhibited excellent leadership on almost all environmental issues so far. This surely gives hope that no such time bombs will be allowed and implanted in the Northeast region. And those who lobby for it — politicians or industrialists — will all be treated as the enemy-of-the-state and be done away with as quickly as possible.