A 6.2-magnitude earthquake struck off Taiwan's eastern coast on Thursday and was followed by multiple lighter aftershocks, the island's weather bureau said, with shaking felt in the capital Taipei.
The quake hit just after midday about 30 kilometres (19 miles) off the coast of Hualien County at a shallow depth of six kilometres.
The US Geological Survey reported a lower 5.9-magnitude reading and a depth of 12 kilometres.
The national fire agency said six hikers who were climbing Yushan, the island's highest mountain, suffered minor injuries when they were hit by falling rocks during the quake.
"The earthquake was felt all over Taiwan because it's very shallow," Chen Kuo-chang, head of the weather bureau's seismological centre, told reporters.
"There have been eight aftershocks so far and we expect more aftershocks in the next three days."
Taiwan's subway and railway authorities both said on Thursday trains were temporarily running at reduced speed but services had not been halted.
There have been 12 quakes over 6.0 magnitude this year, according to the centre, four times the average 2.8 a year, and the second highest since 1999.
A 7.6-magnitude quake in September 1999 killed around 2,400 people, the deadliest natural disaster in the island's history.
Taiwan is regularly hit by earthquakes because the island lies near the junction of two tectonic plates.
Some earthquakes of 6.0 or more can prove deadly, although much depends on where the quake strikes and at what depth.
A much stronger 6.9-magnitude tremor struck Taiwan's eastern coast in September, killing one person and bringing down a handful of buildings.