Markets around the world were hit by this morning's massive earthquake in Japan, with insurers hit hard as investors attempt to assess the cost of damage wrecked by the tremor and resulting tsunami.The UK non-life insurance sector fell back with Amlin , Catlin and Chaucer finishing lower. Life insurers such as Legal & General and Prudential also fell.The tsunami resulting from the earthquake has already killed a large number of people in Japan. Reports say hundreds are dead. Production has been halted at many factories. Japan's central bank vowed to ensure financial stability following the disaster.News of the quake sparked panic among investors, coming as it did just as the local stock market was preparing to close for the weekend.Worries about the global economy and violence in Saudi Arabia had already sent the Nikkei index to a five-week low, down 179 points, or 1.7%, to 10,254.But the quake, measuring 8.9 magnitude, led to further selling after the close, pushing Nikkei futures down 395 points, almost 4%, to 9,975 at one stage in Singapore trade.Things have improved since and credit ratings agency Moody's has already said Japan's debt rating will probably not be affected. The FTSE 100 closed just a few points lower.Seismologists say it is the largest earthquake to hit Japan for over a century, surpassing the Great Kanto quake of 1923 at 7.9 in magnitude.