Japanese shares plunged 1.7% this morning, falling sharply in the closing minutes of trade after the country was hit by a massive earthquake and tsunami. The Nikkei index of the Tokyo Stock Exchange fell 180 points to close at 10,254. The market had already been affected before the earthquake by unrest in the Middle East and euro zone debt worries. It was too early to assess the economic damage, but the quake, centred in northeast Japan, was a potentially destructive 8.9 magnitude and caused a tsunami 10 metres (33 feet) high. Among the early damage was a fire blazing at an oil refinery near Tokyo. Trading volume spiked as the quake sparked last-minute selling, topping 3.15 billion shares, easily the most this year so far.