A 6.8-magnitude quake hit the northern parts of central Japan's Nagano prefecture late Saturday, causing many injuries, building collapses, landslides, and road damages, local reports said.
At least 57 people have been injured in the earthquake that struck around 10:08 p.m. local time (1308 GMT) Saturday, police said on Sunday.
Injuries were reported in Nagano city and Hakuba village, where more than 80 people stayed overnight in an evacuation shelter.
About 10 houses collapsed and at least 10 people were injured in Hakuba, one of the hardest-hit areas. The quake also triggered landslides in Hakuba, some 280 km northwest of Tokyo, which have blocked roads. Some roads in Nagano and Niigata were damaged.
The Nagano prefecture government has enforced the disaster relief law to Hakuba and other villages. The extent of damage caused by the quake is still being probed.
Several aftershocks were recorded following the 6.8-magnitude temblor, with two registered at 4.3-magnitude and 4.1-magnitude respectively. Japan's Meteorological Agency (JMA) warned of possible strong aftershocks in the week.
The quake triggered no tsunami alert, said JMA, adding active fault movements triggered the quake.
The epicenter was initially detected at around 36.7 degrees north latitude and 137.9 degrees east longitude, with a depth of 10 km, said the agency.
The 6.8-magnitude quake was registered at lower 6 of Japan's seismic scale of 7 in parts of the prefecture and lower 5 in neighboring Niigata prefecture, it said.
Japan's public broadcaster NHK said the earthquake lasted about 15 seconds, adding no damage has so far been reported at the Kashiwazaki-Kariwa nuclear power plant in neighboring Niigata prefecture.
The quake triggered blackouts in some areas and bullet train services in the region were affected. The earthquake was felt across much of northern Japan and in Tokyo.
Japanese Chief Cabinet Secretary Yoshihide Suga said late Saturday that the government has set up a disaster relief office and Prime Minister Shinzo Abe has given instructions on rescue works.
Suga also said the government will send members of the Self-Defense Forces to the quake-hit areas.