Note : A second , slightly smaller quake occurred about 30 minutes later in the same area . The first , stronger 9-kilometer deep earthquake did not set off tsunami warnings . It was located about 550 kilometers ( 342 miles ) north - northeast of Tokyo . A stronger March 4 quake triggered a tsunami that led to hundreds of deaths .
NEW : A second , slightly smaller quake hits about 30 minutes later in the same area . The first , stronger 9-kilometer deep earthquake did not set off tsunami warnings . It was centered about 550 kilometers ( 342 miles ) north-northeast of Tokyo . A stronger March 2011 quake triggered a tsunami that led to thousands of deaths .