Tokyo, Japan - A 6.8-magnitude earthquake struck off southwestern Japan late on Monday, causing small tsunamis in the area but no major damage was reported.

The quake was detected around 11 miles off the Kyushu region around 9:19 PM (1219 GMT), according to the US Geological Survey.

The Japan Meteorological Agency (JMA) initially warned of possible tsunami waves of up to three feet high and urged people to stay away from coastal waters.

However, several smaller tsunamis of only around 20 centimeters were detected at ports in the region, the weather agency said.

Live television feeds on Japanese television showed calm seas, as well as vessels operating normally and traffic running smoothly.

Only minor damage occurred, including a broken window at a train station and objects falling off shelves in a few stores, local media reported.

One man was slightly injured after falling over in his home, NHK reported.

The JMA warned in August that the likelihood of a "megaquake" was higher than normal after a magnitude 7.1 jolt that injured 15 people.

That was a particular kind of tremor known as a subduction megathrust quake, which has occurred in pairs in the past and can unleash massive tsunamis.

The advisory – lifted after a week – concerned the Nankai Trough, a 500-mile undersea gully parallel to Japan's Pacific coast.

The JMA said on Monday that the latest quake did not meet the criteria to trigger special warnings for the Nankai Trough again.

"However, it is important to keep in mind that an earthquake could occur at any time, and it is important to ensure that preparations for earthquakes are implemented on a daily basis," it said.