Japan Meteorological Agency warns of 3 metre waves (9.8 ft)after 7.7-magnitude quake.
The earthquake on Wednesday shook buildings off their foundations and led to a landslide in the eastern part of the island.
In the capital Taipei, vehicles pulled over on the side of the road and the city’s subway service was briefly suspended, while tiles were thrown from older buildings and furniture was knocked over with the force of the quake.
A series of aftershocks were felt in the capital about 15 minutes later and continued over the next hour.
Taiwanese authorities issued a tsunami alert for coastal areas, calling on residents to be “vigilant”.
The Japan Meteorological Agency (JAM) said the magnitude of the quake was 7.7, up from an earlier estimate of 7.5.
Wu Chien-fu, the director of Taipei’s Seismology Centre, said the quake was the strongest to hit the island since a 1999 quake that killed 2,400 people.
“It’s felt all over Taiwan and offshore islands,” Wu told reporters.
The JMA said residents in areas around Okinawa Island, Miyakojima Island and Yaeyama Island should immediately evacuate, warning of waves of up to 3 metres (9.8 ft) high.
“Tsunami waves are approaching the coasts. Evacuate as quickly as possible. Waves can hit repeatedly. Continue to evacuate until all warnings are lifted,” the meteorological agency said.
Okinawa’s main airport suspended flights following the alert.
The Philippines’s seismology agency said coastal areas were expected to experience “high tsunami waves”.
“The people in the coastal areas of the following provinces are strongly advised to immediately evacuate to higher grounds or move farther inland,” the agency said in an advisory.