In Japan, at least four people have been killed and over 90 injured in yesterday's 7.1 magnitude aftershock that hit the disaster zone devastated by the massive Earthquake and Tsunami on the 11th of last month. Electricity was cut across a huge area of northern Japan, forcing cooling systems at three nuclear plants to switch to emergency power and plunging more than 3.3 million households into darkness last night. However, at least one back-up supply remained online at all three plants at the Fukushima Daichi nuclear complex. The aftershock has also highlighted the potential risks of nuclear generation in an earthquake zone.The Tsunami alert, immediately issued after by the Japanese Meteorological Agency that sent people fleeing to higher ground, was later withdrawn. The disaster management agency said at least 93 people were confirmed injured in yesterday's aftershocks.