Two strong back-to-back earthquakes struck early Thursday off the northeastern coast of Japan, prompting a short tsunami warning.

A 6.8 quake was centered about 136 kilometers southeast of Hachinohe. It was immediately followed by a 6.7 magnitude quake. There are no immediate reports of damage or injuries.

Officials issued a tsunami warning, but canceled it about one hour later.

Hachinohe is north of the epicenter of the devastating March 8.9 magnitude quake and tsunami.