A strong earthquake struck off the northern coast of Japan on Thursday morning, but authorities said there was no tsunami threat.

The Japan Meteorological Agency said the earthquake measured 7.2 in magnitude, upgrading an initial estimate of 6.9. The quake occurred off the eastern coast of Iwate Prefecture at a depth of about 50 kilometers. The United States Geological Survey recorded the quake at magnitude 6.9.

The tremor struck during the morning rush hour in northeastern Japan and was also felt lightly in Tokyo.

Chief Cabinet Secretary Minoru Kihara said there were no immediate reports of injuries or significant damage.

Prime Minister Sanae Takaichi said the government's emergency response team was gathering information and preparing for possible relief operations if needed. She also urged residents in affected areas to remain alert for aftershocks.

Tomoko Nagane, principal of a primary school in the town of Hashikami, told NHK that she was driving when the earthquake alert sounded and experienced moderate shaking. Although children at the school were safe, some were frightened and crying. Classes were canceled for the day and all students were sent home safely, she said.

Reports from journalists in several affected cities, including Sendai and Morioka, indicated that shaking lasted for a couple of minutes, but no damage was immediately visible. Television footage showed people continuing their daily routines.

East Japan Railway Company said some bullet train services and local rail lines in the region were temporarily suspended while safety inspections were carried out.

Kihara said no abnormalities had been reported at nuclear facilities, including the Fukushima Daiichi Nuclear Power Plant, which was heavily damaged in the 2011 earthquake and tsunami, or at a spent-fuel reprocessing facility in Aomori.

Japan is one of the world's most earthquake-prone countries due to its location along the Pacific Ring of Fire, a region known for frequent seismic activity.