A magnitude 6.3 earthquake shook western Japan early this morning (Friday) while people were still asleep.

The quake hit beneath the Sea of Japan just after 2am local time.

Parts of western Japan felt shaking at five-plus on the Japanese intensity scale. That’s enough to cause concrete walls to collapse.

Japan’s NTV reports light injuries to 19 people over six prefectures as well as burst water mains and landslides on Shikoku island.

Shikoku Electric says its Ikata nuclear plant registered shaking of five-minus, but that checks showed the plant was unharmed.

Japan’s meteorological agency says there was no link between today’s quake and a giant earthquake predicted to hit the Nankai trough.

But officials warned of the likelihood of continued aftershocks over the next week.

The quake comes just three days after the third anniversary of Japan’s devastating 2011 earthquake and tsunami.