A strong magnitude-6.5 earthquake has shaken Taiwan, sending panicked people running into the streets as buildings swayed and bringing public transport to a halt.
The quake struck at 1.11pm on Sunday at a depth of 66.8 kilometres, the island's Central Weather Bureau said, and it was quickly followed by a magnitude-5.4 aftershock.
The epicentre was in northeastern Taiwan but the impact was felt across the island, the bureau said. Residents reported feeling rolling tremors that lasted several minutes.
There have been no reports so far of serious injuries or damage.
In Taiwan's capital Taipei, the quakes forced the service of Taipei Mass Rapid Transit to be suspended for 40 minutes. The quakes also resulted in suspension of part of Taiwan's high-speed rail service.
In Taipei and neighbouring New Taipei City, construction sites that may have become unstable were being checked.
One such site included a 20-story-high building under construction with a crane boom on top that appeared to have nearly broken apart.
Local broadcasters also showed a number of business signs having fallen to the ground, while in some rural eastern parts of the island mountain roads had collapsed and were covered with mud and debris.
The state-run Central News Agency reported that nuclear power plants and the operations of science parks, where Taiwan's important semiconductor high-tech firms are based, were not affected.
According to the Central Weather Bureau, around 30 minutes before the big quake, there was a magnitude-4.5 tremor also centred near eastern Taiwan.
"We don't rule out that, in the following three days, quakes with a magnitude bigger than 4 can occur," the bureau's Seismological Center Director Chen Kuo-chang said at a news conference.
Chen said that, in terms of subduction zone earthquakes, the one at 1.11pm was the biggest recorded since monitoring began in 1973.
Some people reported on social media that several seconds before the strong earthquake they had heard frightening seismic noises.
Most residents in Taiwan received instant earthquake alerts via their mobile phones.
In September 1999, the earthquake-prone island, which sits on the convergent boundary between the Eurasian plate and the Philippine Sea plate, was hit by a magnitude-7.3 earthquake that left more than 2400 people dead.
Australian Associated Press