South Korea quake was second-strongest on record

A rare earthquake that struck South Korea on Wednesday was the second-strongest on record, authorities said.

The 5.4 magnitude tremor hit the south-eastern port city of Pohang in the afternoon, and dozens of aftershocks have occurred since.

It has left at least 57 people injured and more than 1,500 homeless.

In an unprecedented step, the education ministry has postponed the nationwide college entrance exam which had been scheduled for Thursday.

South Korean news agency Yonhap said it was the first time a natural disaster had forced a rescheduling of the crucial exam which students and parents spend months preparing for.Image copyrigh

South Korea rarely experiences tremors, but seismic activity is very closely monitored because a spike is often the first sign that North Korea has carried out a nuclear test.

Last year, a magnitude 5.8 earthquake hit the nearby city of Geongju, but the damage from Wednesday's quake has been more severe.

More than 1,000 buildings, homes and vehicles have been destroyed or damaged.