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Wednesday, 22 October 2008

Earthquakes in Asia
In Asia alone over half a million people have been killed by earthquakes in the eight years of the 21st century. This disquieting fact is reported by James Jackson of Cambridge University – writing in Geology Today (Vol. 24, September-October 2008, p. 179).

The five most recent major Asian earthquakes occurred in: India 2001 (20,000 dead), Iran 2003 (40,000 dead), Indonesia 2004 (250,000 dead), Kashmir 2005 (80, 000 dead) and China 2008 (70,000 dead).
Earthquakes occur when the force of friction resisting movement between the rocks either side of a fault is overcome. Asian earthquakes tend to arise because of plate tectonics, as Africa, Arabia and India all push northwards into Eurasia.
The frequency of earthquakes which cause death tolls of more than 10,000 has risen to 1 every 2 to 3 years (compared with 1 per 5 years from 1600 to 1900). This does not mean that earthquakes are getting more common however, but reflects a rapidly growing population being crammed into relatively poorly built accommodation – such that each earthquake now has much greater potential to cause multiple deaths. This situation is coupled with a tendency for settlement to be attracted to earthquake zones due to faults causing transport corridors through mountainous regions, and because fault zones can create aquifers and springs in otherwise arid areas.
Improved building regulations in places such as Japan and California have shown that death tolls in earthquake zones can be greatly reduced through good planning and high standards of construction. Jackson concludes that if the number of earthquake deaths is not to rise greatly over the next few decades, there needs to be a marriage between geological awareness and political will and resolve in planning construction activity in the rapidly enlarging population centres which fringe the Alpine-Himalayan mountain belt. (JJS)



The May 2008 Chinese earthquake in Sichuan killed 70,000 people

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