Japan earthquake: Fukushima nuclear plant evacuated following aftershock 11 Apr 2011 A magnitude 7.1 aftershock has rattled Japan on the one-month anniversary of the magnitude 9 earthquake that spawned a deadly tsunami. Authorities issued a warning for a three feet high tsunami after today's earthquake. The quake's epicentre was in Fukushima prefecture. Workers battling to contain a crisis at the stricken Fukushima nuclear plant were ordered to evacuate after the powerful aftershock, operator TEPCO said.