At least 21 people people were injured following a6.7-magnitude earthquake that struck Japan's northwestern coast overnight andcaused a slight tsunami, officials announced on Wednesday.
The quake occurred at 10.22 p.m. on Tuesday and had itsepicenter at sea – though near the coast – close to the border that separatesthe prefectures of Niigata and Yamagata, reports Efe news.
As soon as the seismic activity was registered, the JapaneseMeteorological Agency (JMA) issued a tsunami alert that was lifted three hourslater.
The tsunami's waves could be seen in Awashima, Sakata, Sado,Wajima and Niigata, where they reached a maximum height of 0.1 metres (lessthan four inches), according to the agency's data.
Japanese authorities were still checking the state ofbuildings, although no serious structural damage to residences or installationshas so far been identified.
The JMA has urged people in the affected area to remainalert due to the risk of building collapses and landslides as similar tremorsand aftershocks may still occur and in light of the rains forecast forWednesday in part of the region.
The quake led to the temporary closure of some roads andinterruptions in rail services, but no accidents were reported.
Some 10,000 people were affected by the shutdown of thebullet trains, although the popular commuter service has since been restored.
Japan sits on the so-called Ring of Fire in the PacificOcean, one of the world's most seismically active areas.