A powerful earthquake with a preliminary magnitude of 7.1 struck Japan's northern island of Hokkaido early today, swaying buildings, throwing objects off shelves and triggering a tiny tsunami wave that reached the shore.
Thirteen people were injured by the 3:32 a.m. quake, but there were no immediate reports of damage.
Japan's Meteorological Agency quickly issued a tsunami warning for the eastern shores of Hokkaido. Tsunami are potentially dangerous waves triggered by seismic activity.
But agency official Masahiro Yamamoto later told a televised news conference that the agency had lifted its warning, saying that it had detected a 4-inch tsunami and expected only small changes in the ocean's surface.
The quake was centered off Hokkaido's east coast, about 550 miles northwest of Tokyo, 30 miles below the sea surface.
The rocking was felt throughout northern Japan, including Hokkaido's largest city, Sapporo, and Kushiro, on the island's eastern shore.