A powerful magnitude 5.7 earthquake struck Japan’s Aichi Prefecture early on Sunday (8 November), a rare tremor of such strength in the area in 30 years.

Violent shaking jolted residents in several areas from their sleep. More than 20 people were injured, while some homes and shops were damaged. Roads around the local airport were temporarily closed, and public transport services, including Shinkansen bullet trains, were delayed.

According to Aichi Prefecture’s disaster response headquarters, a woman in her 50s fell down the stairs at home during the earthquake, fracturing her right ankle. In Obu city, a foreign man in his 20s was injured after jumping in panic from the second floor of an apartment building.

Injuries were also reported in Nagoya, Toyota city, Hekinan, Nishio and Inuyama, among other places.

Homes, public facilities and shops in several areas were also damaged. A display window at a car dealership in Toyohashi city shattered, scattering glass outside the shop, while books fell from shelves and covered the floor of a bookshop in Toyota city.

The local government also said it received dozens of reports of water supply disruptions within an hour of the earthquake because of ruptured underground pipes.

The earthquake also severely disrupted travel. Japan Railway Tokaido Shinkansen trains operated at reduced speeds between Shizuoka and Gifu-Hashima from the first service until around 9am, delaying multiple trains. Normal services resumed only in the afternoon.

Large crowds of passengers waited in the cold wind on the platforms at Nagoya Station. One frustrated tourist said, “I had planned to go sightseeing in Nara, but I’ve been waiting for more than two hours and no train has arrived.”

Roads around Chubu Centrair International Airport were also temporarily closed following the earthquake.

With the earthquake’s focus in Shizuoka Prefecture, close to the anticipated source zone of a Nankai Trough megathrust earthquake that has the Japanese government on high alert, Aichi governor Hideaki Omura issued a statement overnight urging residents to follow official information closely and remain highly vigilant for possible strong aftershocks.

Nobuo Fukuwa, professor emeritus at Nagoya University, told Japanese broadcaster NHK that there had been few major earthquakes around Aichi Prefecture recently, and that this magnitude 5.7 quake was a substantial one.

Fukuwa said preparations were needed for the possibility of an even larger earthquake.

The Japan Meteorological Agency, however, said the earthquake was unlikely to be directly linked to a Nankai Trough earthquake. It nevertheless warned residents to watch out for aftershocks of the same magnitude or greater over the coming week.

Japanese authorities had previously assessed that the probability of a Nankai Trough earthquake occurring within the next 30 years was more than 60%.

In response, the government set up a dedicated disaster prevention department on 2 November to serve as a “command centre” for responding to such a quake. On the day of its establishment, it urged residents to keep at least a week’s supply of emergency food at home.

Japan lies on the Pacific Ring of Fire seismic belt and experiences hundreds of earthquakes every year. The magnitude 9 earthquake and tsunami that struck eastern Japan in 2011 killed nearly 20,000 people.

In July this year, a powerful magnitude 7.1 earthquake struck Kumamoto Prefecture in southwestern Japan. With post-disaster reconstruction still incomplete, the southern part of the region was also hit by a magnitude 4 earthquake on Sunday.

Fortunately, there were no reports of serious damage or injuries.