A powerful earthquake with a magnitude of 7.4 - the strongest earthquake in 25 years to hit the island- followed by a smaller quake with a magnitude of 6.5 struck off Taiwan's eastern coast Wednesday, according to the US Geological Survey, prompting tsunami warnings in southern Japan.

The first quake, with a magnitude of 7.4, struck at 7:58pm ET (7:58am local time) and had an epicenter located about 18 kilometers (11 miles) south of the city of Hualien and shook buildings in the capital Taipei.