The magnitude 6.7 quake struck on Friday off the coast of Aomori Prefecture at 11:44 am local time (02:44 GMT) at a depth of 20 km (12.4 miles), the broadcaster reported, citing the JMA.
Two 20-centimetre waves were observed in the town of Erimo on the northern island of Hokkaido at 12:35pm (3:35 GMT), and another three minutes later in the Aomori region, the JMA said.
National broadcaster NHK reported that there was no noticeable change in conditions at either port.
Japan’s Nuclear Regulation Authority said there were no immediate signs of abnormalities at the region’s nuclear facilities, Al Jazeera reported.
NHK said that the level of shaking from the quake was less than a bigger magnitude 7.5 earthquake that hit in the same region on Monday and tore apart roads, smashed windows and triggered tsunami waves of up to 70 cm.
Following Monday’s earthquake, which injured at least 50 people, the JMA issued a rare special advisory warning to residents across a wide area, from Hokkaido in the north to Chiba, east of Tokyo, to be on alert for an increased possibility of a powerful earthquake hitting again within a week.
The northeast region is haunted by the memory of a massive magnitude 9.0 undersea quake in 2011, which triggered a tsunami that left about 18,500 people dead or missing.
The JMA issued its first special advisory in 2024 for the southern half of Japan’s Pacific coast, warning of a possible “megaquake” along the Nankai Trough.
The government has said that a quake in the Nankai Trough and subsequent tsunami could kill as many as 298,000 people and cause up to $2 trillion in damage.
Amid fears of a “megaquake”, NHK reported on Thursday that people in the northeast of Japan were stocking up on disaster-related goods such as torches, water storage tanks and support poles to prevent furniture from toppling over due to tremors.
Japan sits on top of four major tectonic plates along the western edge of the Pacific “Ring of Fire” and is one of the world’s most seismically active countries, experiencing about 1,500 earthquakes a year.