TOKYO—Power had been restored to almost all customers in the northern Japanese island of Hokkaido by early Sept. 8, two days after an earthquake caused an island-wide blackout and killed at least 21 people.
But the impact of the 6.7 magnitude quake on Sept. 6 was set to rumble on with Toyota Motor planning to halt operations at 16 of 18 domestic full-assembly plants due to a parts factory shutdown.





