Tokyo shares plunged shortly after opening as investors reacted to the biggest earthquake in Japan's history and the devastating tsunami that tore away entire towns along the northeast coast.
Shares fell 5.42 percent in a post-quake sell-off as the key index sank below 10,000 to its lowest levels since November.
The Nikkei index fell 556.06 points shortly after opening to 9,698.37.
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"We cannot possibly ignore the impact that this quake will have in terms of geographical span and scale -- as well as the psychological impact," Credit Suisse strategist Shun Maruyama told Dow Jones Newswires.
Maruyama cut his Nikkei target for end-March to 9,000 from an earlier 11,000, saying the index may fall to 9,500 on the opening day.
Japan automaker shares plunge
Shares in Japan's top carmakers have plunged by more than 10 per cent as investors react to plant shutdowns after the biggest earthquake in Japan's history.
