Anchor: A four-point-eight magnitude earthquake rattled the southwestern coastal county of Buan on Wednesday morning, the largest that the nation has seen so far this year. The quake and the subsequent aftershocks damaged walls and windows and prompted some schools to suspend classes. 
Our Yun Sohyang has more.

Report: A four-point-eight magnitude earthquake struck near the southwestern county of Buan in North Jeolla Province on Wednesday morning, the strongest tremor to hit the Korean Peninsula and its surrounding waters so far this year.

According to the Korea Meteorological Administration (KMA), the quake occurred about four kilometers south of the county at 8:26 a.m. at an estimated depth of eight kilometers. It is the eighth strongest quake the nation has seen since 1978, when the government began collating seismic data.

As of 2 p.m., 315 reports of vibrations were logged across the country and more than 100 cases of cracked warehouse walls and damaged windows in Buan county and nearby areas were reported.

Kim Young Hee, professor of Seismology at SNU, says that Wednesday's quake is highly likely to have occurred due to an active fold belt. 

[soundbite: Professor Kim Young Hee, Geophysics/Seismology, Seoul National University]
"Near the epicenter, there is what is called an Okchun fold belt, where you can find many fold and fault systems although this fold belt was formed many hundreds of millions of years ago, some part of the fold belt can be seismically active. Although many detailed analyses have not been done yet, because of the shortness of time, it appears that the occurrence of today's event can be highly relevant to the fold system." 

Sixteen aftershocks were reported as of 3 p.m., with the strongest of the residual tremors measuring at a magnitude of three-point-one, occurring at 1:55 p.m. 

[soundbite: Professor Kim Young Hee, Geophysics/Seismology, Seoul National University]
"Aftershocks typically follow after the main shock. They occur near the epicenter. When the main shock occurs, the fault near the epicenter becomes dynamically unstable therefore the aftershocks occur in order to adjust for this dynamic instability. One thing to note is that the aftershock magnitudes are smaller than the main shock and so people living at or close to the epicenter would most likely experience small tremors for coming  days and weeks. " 

According to the education ministry, some schools either suspended classes or reduced class hours in the provinces of North Chungcheong, South Chungcheong, North Jeolla and South Jeolla. The ministry as of 5:30 p.m. said that there have been facility damages, including some cracks and leaks, at a total of 18 schools, including eight schools in the Buan area.

The interior and safety ministry activated the lowest level of the three-tier emergency response posture of the Central Disaster and Safety Countermeasures Headquarters soon after the initial quake and set the earthquake crisis alert level for the country to “alert,” the second highest in the four-tier system. 

President Yoon Suk Yeol, who is on a state visit in Kazakhstan, instructed the government to carry out a swift damage and safety assessment. 

Prime Minister Han Duck-soo immediately convened a meeting and ordered the government to conduct emergency inspections of national infrastructure such as nuclear power plants. 

The Nuclear Safety and Security Commission stated that it had confirmed that there were no issues with the safety of nuclear power facilities nationwide following the earthquake.
Yun Sohyang, KBS World Radio News.