SEOUL, March 13 (Yonhap) -- Over 80 percent of South Korea's buildings remain vulnerable to earthquakes because they were not constructed following seismic design codes, a report by the state disaster agency said Sunday.

The report comes as concerns grow that the country may no longer be free from quakes as an 8.9 magnitude earthquake hit neighboring Japan on Friday, sending a high tsunami that ripped through towns and cities across its northeastern coast. Japanese media estimate that at least 1,300 people were killed.