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Killer earthquakes on the rise

Killer earthquakes on the rise

The last decade has seen an intensification in earthquake activities. The 2004 Sumatra quake in Indonesia, which registered 9.3 on the Richter scale, has triggered stress in many areas. The Sikkim earthquake could be a manifestation of this stress. Earthquakes, some scientists believe, are on the rise. The earthquake in Fukushima in Japan had a magnitude of 8.9 and was the largest in the recorded history of Japan. The February 2010 Chile earthquake registered a similar magnitude as the Japan quake while the January 2010 quake in Haiti had a magnitude of 7.0 on the Richter scale. Prof D.K. Paul, an earthquake engineer with IIT Roorkee, believes the pushing of the Indian tectonic plate under the Eurasian plate (at the rate of 5 cm per year) results in stresses which over a period of time, manifest as earthquakes.

“The continents of Eurasia and the Indian sub-continent meet in the north east and the Sikkim region is located close to the fault line. This means tremendous strain is building up ever day,” said Paul. Environmentalists are not willing to buy this explanation in its entirety. Global Disaster Watch believes the Sikkim quake may have been induced by the 35 hydel projects being built across the Teesta river. The central government’s dream is to transform the north-east into ‘India’s future powerhouse’ by building about 168 dams in the region.

While the river Teesta flows in a north-south direction, the Himalayan fault lines lie in the east- west direction. A major fault line is located at Kalijhora (considered the best location to study Himalayan fault lines) and Teesta Low Dam Stage 4 is located at Kalijhora. “The sheer weight of water can trigger a seismic movement,” Paul said. This has happened in the past. In the sixties, a major earthquake in Maharashtra was triggered by the Koyna dam located on the Sahyadri Hills. Though the role of the dams on the River Teesta in the recent quake has yet to be studied, the earthquake could have been induced or accelerated by what scientists describe as ‘dam induced seismicity.’ Globally, there are over 90 identified sites of earthquakes triggered by the filling of water reservoirs.

Manoj Misra of Yamuna Jiye Abhiyan confirms that “Huge amounts of water standing in earthquake areas can aggravate seismicity. But dams are being built recklessly over the entire Himalayan belt not keeping mind that these mountains are fragile and also seismically vulnerable.”

A committee set up by the West Bengal government studying landslides had warned the West Bengal way back in 2000 against the damming of the Teesta river but these recommendations, were thrown into the dustbin.

The Sikkim earthquake has once again brought to the forefront India’s lack of disaster preparedness. This, despite the fact that India has set up a National Disaster Response Force (NDRF), whose primary goal is to get to a calamity zone at the earliest. The Sikkim capital falls in seismic zone 5 and the National Disaster Management Authority had recommended an NDRF unit be stationed in Gangtok.

This suggestion was not followed and so, though, ten NDRF teams took off from Delhi and Calcutta on September 18 night, in an attempt to reach northern Sikkim which was facing the brunt of the destruction, they remained stuck in Siliguri. It was left to the army engineers and the Border Roads Organisation to clear debris from landslides at more than 20 places on the National Highway 31A, Sikkim’s only link with the rest of the country.

Why is India so poorly prepared for earthquakes especially since India has lost 23,000 people to quakes between 1990-2006. Latest technological innovations in safe seismic engineering are not being implemented and even new buildings fail to comply with building codes. Unless buildings are not made earthquake proof with the aid of deep foundations and massive shock absorbers that dampen seismic energy, buildings will remain unsafe.

Japan considered one of the world’s most quake prone countries has strict building codes in place, good engineering and has also ensured that every child is taught to participate in monthly quake drills to teach them how to behave during a quake.

The result is that despite the tsunami and a devastating quake in Fukushima, the Japanese public including school going children were taught to remain calm, wear their helmets and form lines while evacuating even as the buildings around them shook violently. Prof AS Arya, retired from IIT Roorkee and presently a member of the Bihar state Disaster Management Authority pointed out, “Till today, people have not been able to reach the far flung villages of northern Sikkim where people could still be buried under the debris.”

Involved with the massive reconstruction work that took place in Bhuj following the earthquake, Arya believes that the Sikkimese people must be taught to reconstruct their homes using appropriate technologies. There is no dearth of know how including how to construct using safe non-engineered construction.”

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Brian Shiro 27/09/2011 - 01:16am

We saw a similar pattern of increased numbers of large magnitude 8.5+ earthquakes in the 1960s following the great 1960 magnitude 9.5 Chile earthquake. Now, the 2004 magnitude 9.3 Sumatra earthquake may be causing a similar increase in the rate of large events. If history is any guide, this should last about a decade, so by 2014 it should start to tail off to "normal".

VK6KPH 26/09/2011 - 01:04pm

Maybe governments could give money to the researchers that are trying to get these pre-sesimic warnings operational instead of paying incompetent financial and banking executives that do well:
Not much except gamble our lives away. In India you have at least several scientific groups that are doing research on little or no money. Same here in Australia and the USA and China etc.

Friedemann Freund 26/09/2011 - 12:45pm

The large-scale catastrophic rupture events in the Earth crust are driven by large-scale tectonic processes such as the continuing subduction of the Indian subcontinent underneath the Eurasian plate. The horizontal forces driving these momentous movements originate deep below, surely as deep as 400-600 km, due to the slow but never-ending upwelling of the Earth's deep mantle. Down there the rocks are hot. They are plastic and flow. Higher up, in the Earth's middle to upper crust, rocks are cooler and, hence, brittle. That's why they can accumulate elastic energy and then rupture suddenly when a certain threshold of accumulated stress is exceeded. Still, these rupture processes, which lead to large earthquakes, start almost always at a depth that is large compared to what we humans can do at the surface of the Earth, between 5-35 km.
It is true, building large hydrodams changes the load on the surface of the Earth crust and can indeed trigger earthquakes deeper below if the stresses down there have already accumulated to a dangerously high level. In fact, any load change on the surface of the Earth can trigger seismic activity: The tides, arising from the gravitational interaction between Earth and the moon and the sun, do it. Even changes in the air pressure, atmospheric high and low pressure regions, have been recognized to correlate with the number and distribution of earthquakes.
It is wrong to say, for instance, that building dams "causes" earthquakes. Such engineering project can affect earthquake occurrences only in a very indirect way: by slightly shifting the forces that act on the rocks deep below and cause them to respond differently than without the extra overload of a dam.
It is true, sometimes, the earthquakes triggered by a dam project can be larger than those that might have occurred anyhow sooner or later in about the same region. Therefore, it is necessary to discuss these issues and try to take countermeasures to prevent or minimize damage and loss of life.
Going all the way to the extreme and decide not to build any dams is foolish in its own ways. One has to weigh the benefits, which dams provide to the society, versus the dangers of a slightly altered, maybe increased regional seismicity. A more reasoned approach would be if the government decides to set aside a fair portion of the money needed to build a dam for regional infrastructure projects that would improve the the engineering safety of public buildings and private houses.

chris 25/09/2011 - 07:59pm

I'm scared, can somebody make me feel better?

VK6KPH 26/09/2011 - 01:10pm

@Chris: Sorry no human can do that. The governments are too busy, mismanaging the environment/ economy and everything else they touch! They cannot do what they cannot understand, nor want to.
In India there are several groups of scientists that are trying to develop techniques that maybe used one day to see the precursors 100%. But they have little or no funding. Hopefully that will make you feel better? (I suppose not)

John Christotpher Sunol 25/09/2011 - 10:37am

The earthquakes are getting larger, showing that the time of reckoning is coming quickly

Kuzma 27/09/2011 - 03:34am

i agree..the day is fast approaching that we should get down on our knees and ask Jesus for forgiveness and repent. But that would be to easy. Most people will just say its nature taking its course, happened before and all that other stuff.

Rod Bravender 25/09/2011 - 08:04am

I'm glad to see somebody's finaly listening to the fact that the dams we are building are causing earthquakes. That's not the only thing. The oil and gas drillings doing as also the mining for coal are litterly tearing off mountains using explosives.