The Japan Meteorological Agency said on Tuesday that weak tsunamis (lower than 0.66 feet high) were observed in the Awashima island, Niigata Prefecture, and the city of Sakata in northern Japan, following a 6.8 magnitude earthquake earlier in the day.
The agency warned that bigger waves might arrive later.
Japanese Chief Cabinet Secretary Yoshihide Suga said during a press conference that the earthquake caused power outages in residential houses. The secretary noted that as many as 5,900 houses in Yamagata prefecture were left without electricity, while in Niigata prefecture 2,300 houses were out of power.
However, later in the day, the NHK TV broadcaster stated that the tsunami threat was cancelled.
In the aftermath of the 6.8-magnitude earthquake, Japanese authorities checked if people were killed or injured, Japanese Chief Cabinet Secretary Yoshihide Suga said.
"We are verifying whether there is any human damage ... There is a possibility that strong aftershocks will continue to occur. We ask people in areas where the quakes are strong to be following the information on evacuations provided by local authorities, as well as television and radio," Suga told a briefing, as quoted by the NHK broadcaster.
According to Kyodo news agency, four people in the city of Sakata and one man in Murakami were injured due to the earthquake.
The reports come after an earthquake hit Japan's prefectures of Niigata and Yamagata.