Another powerful earthquake has just hit the disaster region in north-eastern Japan. The magnitude 7.4 quake, probably an aftershock of the magnitude 9.0 quake on March 11, occurred at 13.1 kilometres depth 330 kilometres northeast of Tokyo, according to the US Geological Survey. A tsunami warning was issued, but has now been lifted.
Reuters reports that workers have been evacuated from the crippled Fukushima Daiichi nuclear plant.
NHK TV news is reporting that Higashidori nuclear power plant is currently on emergency backup power. The broadcaster also reports that Japan’s nuclear agency says that 2 out of 3 power transmission cables can’t be used at the Onagawa nuclear power plant. The plant operator, Tohoku Electric Power Corporation, had shut down the plant just after March 11.
NHK also reports that the Rokkasho nuclear reprocessing facility has lost power, and is relying on an emergency power generator.
The Japanese Ministry of Economy, Trade and Industry says in a statement that cooling of spent fuel rods is being maintained at the Higashidori plant. It adds that TEPCO, the operator of the Fukushimi nuclear plant, reports no change in radiation levels at the site following the earthquake; and confirms that the Rokkasho nuclear reprocessing facility has lost power.
In a statement provided by the UK’s Science Media Centre, David Rothery, a geoscientist at The Open University, said that the earthquake “is the largest aftershock we’ve seen following the M9.0 quake on 11 March. It was caused by a continuation of the same process, namely the Pacific plate being forced (subducted) below Japan, as stress transfer occurs along the currently-displacing region of the subduction zone. Fortunately, at a source depth of nearly 50 km the ground (and sea-water) displacement is less than would have been caused by a shallower quake of the same magnitude. A 2 metre high tsunami was forecast by the Japan Meteorological Agency within 2 minutes of the quake’s occurrence, but only for immediately adjacent stretches of coastline.
“Except for any places where tsunami walls and especially tsunami gates have not been put back in repair after last month’s disaster, I doubt if this tsunami will cause much damage. It occurred at nearly midnight local time, so there will have been few if any people near the vulnerable sea-front.”
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