TOKYO - An 8.3 magnitude earthquake struck off Japan's northern coast in the Pacific on Saturday, setting off tsunami warnings and sending thousands of residents along the archipelago's eastern coast fleeing to higher ground.
But about an hour later, a tidal swell of about 4 inches was recorded in the northeastern coastal town of Nemuro, the agency said.
Officials had said earlier that the tide receded about 4 inches in Nemuro, in the first signs that a tsunami was approaching. Most other areas said there had been no visible changes to the sea level.
Small swells in the tide were also observed in other coastal towns on the island, including Kushiro, Abashiri and Otaru, the agency said.
Hokkaido disaster prevention official Haruyuki Komatsu said the island prefecture issued evacuation orders to 85,000 people in 22 coastal towns, and that thousands of people had gathered at community centers.
The quake struck around 1:24 p.m. about 310 miles east of Etorofu, the largest of a disputed four-island chain known as the Northern Territories in Japan and the Kuril islands in Russia, the agency said.
The 8.3 magnitude quake struck 19 miles below the seabed, the agency said.