7.3 magnitude quake strikes off Japan's east coast: USGS
Blue-coloured carp streamers fly at the tsunami-devastated city of Higashimatsushima, Miyagi prefecture on May 3, 2013
The quake struck at a depth of 10 kilometres (6.2 miles) at 3:10am local time (1710 GMT Friday), 320 kilometres southeast of Ishinomaki in Miyagi Prefecture, according to the US Geological Survey.
The USGS intially said its magnitude was 7.5, and issued a green alert on its website, signalling a low probability of deaths or economic losses.
Eastern Japan, a seismically active region, was struck by a 6.5 magnitude earthquake last month causing tremors to be felt 600 kilometres away in Tokyo.
More than 18,000 people died when a 9.0 magnitude sub-sea earthquake sent a towering tsunami barrelling into Japan's northeast coast in March 2011 in the country's worst post-World War II disaster.
Cooling systems at the Fukushima nuclear plant were knocked out, sending reactors into meltdown and forcing tens of thousands of people to flee.
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