Tuesday, May 13, 2008

Chinese earthquake could be due to global warming

Chinese earthquake could be due to Himalayan glacier-melting

The May-12 Richter-7.9 earthquake in the Sichuan province of China may be caused by glacier-melting caused in turn by global warming. The result is so common it even has a name “glacial earthquake”. The Sichuan earthquake could be one of these glacial earthquakes, and if so certainly not the first one, nor the last.

Relevant to Sichuan are the Himalayas. Himalayan glaciers have shrunk due to three factors:

· Higher temperature thaws the glaciers. According to the International Center for Integrated Mountain Development (ICIMOD), “The average temperature in the Himalayas in the northern part of Nepal rose about 2 degrees between 1970 and 1994; in the rest of Nepal, more than 3 degrees.”
· Global warming changes snow into rain that melts the glaciers, and form glacial lakes · The amount of snowfall has decreased.

The Nepalese Himalayas alone contain more than 3,000 glaciers, each kilometers long and hundreds of meters wide, weighing billions of tons. There are approximately 70 extra-large glaciers in Himalaya, covering about 166 km2 or 17% of the mountain area.

With glacier meltdown comes weight redistribution on a mammoth scale.

The melting of these glaciers has been accelerating.

· Thickness-wise, in the period of 2000-2004, a thinning of about 10 m occurred below 4000 m altitude, and 2 m above 5000 m.
· Length-wise, the Chhukhung Glacier, for example, retreated at about 5 m per year in the late 1970s, which increased to about 20 m per year in and after the 1990s.
· Weight-wise, the shrinking of the AX010 Glacier, which accelerated from 2.7 m per year in the 1980s to 12.5 m in and after the 1990s, resulted in the loss of more than 1 million tons of ice in 20 years through 1999.

The Himalayas and the surrounding mountain ranges are not the most geologically stable region to begin with. The northward incursion of the Indian subcontinent into SE Asia continues and the Himalayas continue being built and elevated, as does the folding of the surrounding ranges, including those in the Sichuan province of China where the earthquake occurred. The redistribution of weight by the glacier melting will cause seismic events in areas where ill-settled sub-plates hang on to each other by their fingernails as it were, slipping violently against each other at the slightest disturbance.

If the above is true, then we can expect more devastating earthquakes to come. Likewise, it can be predicted that the massive melting of the Greenland and Antarctic land-ice will generate earthquakes in and around these regions.

Anthony Marr, founder and president
Heal Our Planet Earth (HOPE)
Compassion for Animals Road Expeditions (CARE)
Global Emergency Operation (GEO)

The following article gives more details.

Glaciers’ melting main reason for quakes: seismologists

By Khalid Mustafa

ISLAMABAD: Seismologists all the over the world have found that another serious consequence of glaciers melting is “glacial earthquakes” - the new indicator after analysing worldwide 182 earthquakes between January 1993 and October 2005.

Explaining the relation between glaciers melting and earthquakes, a WWF consultant told The News that when a glacial ice of one cubic metre melts, it means lightening of one tonne load on earth’s crust (called tectonic plates).

The WWF consultant says “melting of one cubic metre glacial ice frees the plates to move against each other and causes friction needed to make earthquakes. But as the glaciers melt and their load on the plate lessens, there is a greater likelihood of an earthquake happening to relieve the large strain underneath.”

Even though shrinking glaciers make it easier for earthquakes to occur, the forcing together of tectonic plates is the main reason behind major earthquakes.

The Indian plate moves 5cm closer to Asia each year and Tibet moves 32mm closer to Asia each year but glacier melting accelerates or triggers earthquakes.

In a new study, NASA and United States Geological Survey (USGS) scientists found out that in the 1979 earthquake in southern Alaska, which was called the St. Elias earthquake, was promoted by wasting glaciers in the area. The earthquake had a magnitude of 7.2 on the Richter scale.

In Pakistan, the snow-capped mountain glacier is shifting very rapidly toward higher region, particularly in Azad Jammu Kashmir and Kaghan/Naran Valley. Some glaciers are vanishing due to massive human intervention and deforestation.

During the last 20 years, the shifting of snow-capped glacier can easily be checked from Sarwaali Peak (6,326 meters) - the highest mountain in Azad Kashmir. This shifting ice-cap and the vanishing of a small glacier along the Line of Control up to NJ 9842 may be another cause of the 2005 earthquake.

Unfortunately, all major Himalayan glaciers, including Siachen, are on the Eurasian continent (tectonic plate). The Indian plate that is already moving toward it by 1.6 inches per year due to the melting of glaciers is another great threat to the population living in the region.

Arshad H Abbasi predicted that the Himalayan glacier’s melting may cause more severe earthquakes in South Asia.

Melting of glaciers has serious consequences because when a glacier melts it unleashes pent-up pressures on the earth’s crust, causing extreme geological events such as earthquakes and tsunamis.

A cubic metre of ice weighs nearly a tonne and most of the Himalayan glaciers are hundreds of metres thick. When the weight is removed through melting, the suppressed strains and stresses of the underlying rock come to life. The weight suppresses the earthquakes, but when ice melts earthquakes are triggered.

The retreat of ice sheets 10,000 years ago also triggered a wave of powerful earthquakes in the Himalayas.

Since iso-static rebound continues for thousands of years, it may still be contributing to quakes in eastern Canada, says geoscientist Patrick Wu of the University of Calgary.

Interestingly, the earthquake data of Siachen glacier and the Saltoro range itself speaks of its retreat. Between the years 1983 and 2000, earthquakes having magnitudes 4 to 5.2 were recorded. These earthquakes activated avalanches and had consequences as regards casualties of both the forces fighting over the Siachen glacier. As reported only 3 per cent of the casualties were caused by hostile firing. The remaining 97 per cent have fallen prey to the altitude, weather and avalanches.

A joint Indian-Chinese team plans to chart remote Himalayan glaciers that are rapidly melting, threatening the great rivers that give life to the subcontinent - one of South Asia’s most fertile regions. But it could not give any substantial result unless the melting of the third pole (Siachen) is not addressed.

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