Japan lifts tsunami warning after quake 11 Apr 2011 Japan has lifted a tsunami warning issued following the 6.6-magnitude aftershock which rocked the country on the one-month anniversary of the March 11 twin disasters. On Monday, a three-foot tsunami warning was issued after the earthquake struck Japan's northeastern coast. All advisories and warnings were lifted about an hour later. Japanese officials reported the aftershock at 7.1 before revising it down to 7.0, but the US Geological Survey said the quake was closer to a magnitude of 6.6.