The exact number of casualties remained unclear as rescue efforts continued to unfold on Saturday.

Mashiki became the worst hit town following the first quake on Thursday which collapsed houses and toppled roofs. Saturday's quake furthered the damage to the town and its people.

The powerful 7.3 magnitude earthquake struck southern Japan early on Saturday, killing at least 18 people, injuring more than 1,500 and trapping people in collapsed buildings, barely a day after a quake killed nine people in the same region.

The very large quake came as emergency responders were working to reach areas already affected by a 6.2 magnitude tremor that struck late Thursday.

Aerial footage shows collapsed buildings, evacuees and a landslide after a second large earthquake in southern Japan.

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