NEW : Six people were killed and three injured in Tuesday 's quake . It was centered about 77 miles east-southeast of Tokyo . The epicenter is a shallow, narrow trench that runs along the Pacific Ocean floor for hundreds of kilometers ( miles). The earlier quake prompted workers at the Fukushima Daiichi plant to evacuate briefly .
NEW : Six people were killed and three injured in Tuesday 's quake . It was centered about 77 miles east-southeast of Tokyo . Monday 's 6.6-magnitude quake triggers several landslides in Iwaki . The earlier quake prompted workers at the Fukushima Daiichi plant to evacuate briefly .