A 6.1 magnitude earthquake struck 34 kilometres off Taiwan's eastern city of Hualien on Friday, with no immediate reports of damage from what was the second strong tremor to hit the island in less than a day.

The quake also shook buildings in Taipei. Authorities said subway services in the city continued at lower speeds.

The quake had a depth of 9.7 kilometres, the weather administration said, and followed a 5.7 magnitude earthquake that struck off Taiwan's northeastern shore on late Thursday.

Weather officials have warned of the risk of landslides in mountainous areas following days of rain.

Taiwan lies near the junction of two tectonic plates and is prone to earthquakes.

In April, Hualien was hit by the biggest earthquake to affect the island in at least 25 years. Nine people were killed and more than 900 injured. (Reuters)