India site of the next big quake and massive deaths?

Reply Tue 30 Mar, 2010 12:48 pm
Today's quake:

Magnitude 6.4

* Tuesday, March 30, 2010 at 16:54:48 UTC
* Tuesday, March 30, 2010 at 10:24:48 PM at epicenter
* Time of Earthquake in other Time Zones

Location 13.616°N, 92.858°E
Depth 45.4 km (28.2 miles)
Distances 215 km (135 miles) N of Port Blair, Andaman Islands, India
405 km (250 miles) SSW of Pathein (Bassein), Myanmar
825 km (510 miles) W of BANGKOK, Thailand
2310 km (1440 miles) SE of NEW DELHI, Delhi, India




Earthquakes continue
Spencer Pyke, Copy Editor
Issue date: 3/18/10 Section: National

A series of earthquakes hit Indonesia, Myanmar and India on Saturday, March 13 and into the early hours of Sunday morning, but no casualties or damages were reported.

The largest of the quakes registered at 7.0 and struck around 10 a.m. Sunday local time north of Ambon, which is located on the Indonesia's Moluccan Islands, according to an article on rttnews.com.

The earthquakes come weeks after Chile and Haiti were hit by destructive quakes and days after 10 aftershocks struck Chile on the inauguration day of their new president, Sebastián Piñera. The aftershocks took place within seven hours of each other and the largest magnitude was recorded at 6.9, according to the Boston Globe website.

The 6.9 aftershock in Chile was nearly as strong as Haiti's 7.0 magnitude quake that struck and devastated the Caribbean island on Jan. 12 taking the lives of more than 230,000. Haiti's lack of infrastructure made the island's quake the most devastating of the ones that have occurred since.

Seth Borenstein of the AP attributes the mass devastation of recent quakes to increased urbanization along fault lines, not as a result of more violent tectonic movement.

"More people are moving into megacities that happen to be built on fault lines and they're rapidly putting up substandard buildings that can't withstand earthquakes, scientists say," Borenstein said, according to multiple news sources.



Preparing for a big earthquake
N. Gopal Raj

“Earthquakes don't kill people, buildings do.” The adage is very much on the minds of seismologists and engineers who worry about what might happen if India were rocked by a powerful quake. Haiti's experience, where 2,30,000 people are thought to have perished in an earthquake that hit the Caribbean island in January, has heightened those concerns.

The Haiti quake was more than twice as lethal as any previous magnitude 7 event, observed seismologist Roger Bilham of the University of Colorado in a report in Nature.

The death and injury that befell about 15 per cent of those living in and around the Haitian capital were the direct consequence of decades of unsupervised construction, when every possible mistake went unchecked. “In recent earthquakes, buildings have acted as weapons of mass destruction,” Dr. Bilham went on to point out. Such deaths could be reduced significantly if minimal construction guidelines were mandated in all cities, especially those with a history of previous earthquakes.

That advice undoubtedly applies to India, which is no stranger to earthquakes. Many strong earthquakes strike at the Himalayas, the vast mountain chain, extending 2,900 km, that was thrown up when the Indian plate slammed into Eurasia between 40 million years and 50 million years ago. The strains produced by the Indian plate continuing to grind steadily northwards get released periodically in the form of earthquakes.

Just south of the Himalayas are vast plains where many populous towns and cities have sprung up on alluvial soil. This soil amplifies the shaking of the ground that an earthquake in the mountain produces.

“It is a big problem in India,” said Dr. Bilham. The Brahmaputra, the whole Gangetic plain and the Punjab are the worst places to site large cities. There may be as many as 50 million people living in the cities.

Buildings, bridges, power plants and other structures can be designed to withstand earthquakes. Over the years, the Bureau of Indian Standards (BIS) has issued quake engineering codes that lay down specific requirements for various structures. For this purpose, the country has been divided into four zones of differing seismic risk. However, the codes are often not mandatory or are poorly enforced.

The country was going through a major development phase wherein infrastructure was added at an unprecedented pace, he pointed out in a paper published in 2005. It was a great opportunity to ensure that all new structures met seismic requirements. Instead, a huge number of unsafe buildings were continuing to be built every day in different cities and towns.

On the Andaman and Nicobar islands, for instance, a region of high earthquake risk, various buildings, jetties and even an important bridge were put up without paying heed to the seismic codes. When a quake of 9.3 magnitude that produced the lethal Indian Ocean tsunami struck in December 2004, these structures were badly damaged, in some cases irreparably, Dr. Jain and others observed in another paper.

The biggest problem was that the earthquake engineering codes were simply not being followed, he said during the interview. “First, we need to agree that we will enforce the codes.” The Central and State governments as well as the local authorities must act to ensure that unsafe buildings do not continue to be put up, he said.

Many existing buildings were likely to be unsafe in the event of a quake, he said. There had to be a long-term strategy to survey and retrofit at least important buildings, such as hospitals, so that they would become less vulnerable, he added. This might take decades but the process must start immediately.

The number of houses in the country went up by 45 per cent between the censuses of 1991 and 2001, said Anand S. Arya, Emeritus Professor at the Department of Earthquake Engineering in IIT, Roorkee. The number of “kachcha” houses made of clay had remained practically the same while those made with burnt brick had increased The latter, depending on the mortar used, would be a little less vulnerable than clay houses. But as most builders of brick houses would not probably have followed the code for earthquake resistance, these too could be badly damaged. The Indian code applicable to houses balanced the need for safety with what people could afford, pointed out Dr. Arya, who chairs the BIS committee for earthquake engineering codes. Even in the zone with the highest seismic risk, following the code in the construction of a house would increase its cost by only about six per cent. On the other hand, retrofitting earthquake resistance features could cost twice as much.
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Reply Tue 30 Mar, 2010 06:50 pm
see if you cant find any additional data about the migration (upward ) of the hypocenter of these mini seisms, and did anybody print out the changes among the P waves and Componenst of the S waves (Sn/Sg)
Reply Tue 30 Mar, 2010 09:03 pm
Some technical data for today's 6.6 Andaman quake here. I don't understand it well enough to draw any conclusions from it:


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Reply Tue 13 Apr, 2010 08:36 pm
Looks like it is going to be the region around Tibet this time...
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