TOKYO — A powerful magnitude 6.9 earthquake struck off the coast of northern Japan on Sunday evening, triggering a tsunami advisory and a series of aftershocks, the Japan Meteorological Agency said.

The quake hit at 5:03 p.m. local time off Iwate Prefecture at a depth of 16 kilometers (10 miles).

The agency initially reported a depth of 10 kilometers before revising the estimate.

There were no immediate reports of injuries, major damage, or abnormalities at the two nearby nuclear power plants.

A tsunami advisory — warning of waves up to 1 meter (3 feet) — was issued for parts of the northern coastline and remained in effect more than two hours after the initial quake.

Public broadcaster NHK urged residents to stay away from coastal areas and warned that additional strong shaking was possible in the coming days.

Small tsunami waves were recorded, including 10-centimeter (4-inch) waves in Ofunato, Ominato, Miyako and Kamaishi, and up to 20 centimeters (8 inches) in Kuji.

The meteorological agency warned that tsunami waves may continue for several hours and could increase in size.

The quake was followed by several aftershocks affecting Iwate and parts of Hokkaido.

Kyodo News reported temporary power shortages, while JR East briefly suspended bullet train services in the region.

Northeastern Japan is highly earthquake-prone and was the site of the 2011 triple disaster — a massive quake, tsunami, and the Fukushima Daiichi nuclear meltdown — which killed nearly 20,000 people, mostly from the tsunami.

Thousands remain displaced from restricted zones, and protests over nuclear safety continue to this day.

Meteorological officials said Sunday’s quake was not believed to be directly linked to the 2011 disaster but noted the region’s long-term risk for major seismic activity, including a significant quake recorded in 1992.

Japan sits along the Pacific “Ring of Fire,” making it one of the most earthquake-prone countries in the world. — Agencies