Why did Asian markets plummet?

An investor monitors the stock market at a securities brokerage in Taipei on April 16, 2013. Asian shares were mixed on April 16, with earlier losses pared after a huge sell-off on Wall Street, while traders were spooked by a double bombing that hit the Boston Marathon.
An investor monitors the stock market at a securities brokerage in Taipei on April 16, 2013. Asian shares were mixed on April 16, with earlier losses pared after a huge sell-off on Wall Street, while traders were spooked by a double bombing that hit the Boston Marathon.

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    Why did Asian markets plummet?

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Markets down on worries over central banks and growth in China. CNN's Diana Magnay reports.