Bhutan: Some truths to take home

Japan has always been known for being tectonically active.

Preempting disastrous quakes, it prepared relentlessly for years, like no other nations across the world, building seismic resistant structures, as global citizens watched in awe.

The March 11, 2011 earthquake, experts have said, was a result of movement along two major plate boundaries that caused a tremour almost a thousand times more powerful than what Bhutanese in the east experienced about two years ago.

Bhutan too has been warned of being situated on a fault line on the Himalayan range, where a major earthquake, much like the one Japan recently experienced, awaits to occur.

Although the government is educating people on disaster management and demanding strict building rules, geologists say it is high time Bhutan set up its own seismic stations to prepare itself for a disaster that is unpredictable but expected.

Geologist and expert on earthquake engineering Dr Karma Kuenza said, with seismic stations, the nation would know exactly which parts of Bhutan were prone to earthquakes. “If we need to know how Bhutan is behaving to earthquakes, we need to know our local zones,” he said. “We have no information of the sort today.”

Despite support from the government on the need for such stations, lack of budget, as always, stands in the way to implementing the plan.

Building the stations, he said, alone would cost Nu 67M.

“Work is underway and we’ve partnered with some universities and professors in Japan and Germany,” he said. “It should take a few more years for the stations to start running.” Once established, all portable stations placed across the country would be connected to a central system at the headquarters.

“They’ll be automatic, meaning when a major earthquake strikes, they’ll tell you in real time, the magnitude and location, and also record information on any other small earthquakes,” he said.

The 1950 Assam earthquake, Dr Karma Kuenza said, was about 80km away from the nearest Indo-Bhutan border.

“It was about 200km from Trashichhodzong, yet it destroyed a part of the dzong,” he said. “The effect of earthquakes, above magnitude eight, can be felt within a radius of 200km.”

In the last 100 years, about 18 large earthquakes occurred in the Himalayan region. The large earthquakes that were felt in Bhutan include the 1713 Arunachal Pradesh earthquake (M7.0), the 1897 Great Shillong earthquake (M8.3), the 1905 Kangra earthquake (M8.0), the 1934 Bihar-Nepal earthquake (M8.1), the 1947 Assam earthquake (M7.8) and the 1950 Assam earthquake (M8.7).

Bhutan, he said, is divided into two zones by a fault. A fault is a place where earthquakes occur and both Japan and Bhutan are on fault lines.

“We’ve a major fault in Bhutan and so should expect earthquake mostly in the southern belt, because that’s where the earthquake faults are,” he said.

This fault runs more than 2,000km from east to west of Himalayas.

A study by a geologist from the university of Colorado has predicted that the region, where Bhutan is, should expect an earthquake of magnitude of 8, 8.2 or 9.

Dr Karma Kuenza explained that earthquakes occur when the stress built from the continuous movement of plates become too much that they break.

The study said that the Himalayan region is between the Tibetan plate, which is fixed and the Indian plate, which is moving and pushing, 2 cm every year. In 100 years, it would have moved by two metres and in 200 years, four metres.

“And if its four metres of strength accumulation, it will break and the impact of that would give an earthquake of 8 magnitude,” Dr Karma Kuenza said. “But, for the last more than 200 years, even with the four metres of strain, there has been no earthquake in the Himalayan range. And based on the movement and the prediction, we’re actually in a very crucial earthquake prone area.”

Bhutan doesn’t have data to divide itself into zones, safe or prone to earthquakes but based on India, eastern Bhutan falls on zone five and western Bhutan falls on zone four. This means it’s in a zone, where the biggest tremors of an earthquake can be felt.

“That’s why all structures built in Bhutan are built for a big earthquake, with bigger bars and columns and only five storied tall, which are more expensive,” Dr Karma Kuenza said. “And the last earthquake was a national wake up call.”

Like the 1923 quake in Japan, which initiated a massive effort to predict earthquakes and tsunamis. Scientists at Japanese universities received millions to support projects on earthquakes.

Bhutan has at least started.

Source: Kuenselonline