A 5.4 magnitude natural disaster hit the southeastern Korean city of Pohang early Wednesday afternoon.
Among 24 reactors in the nation, 18 are located along the southeastern coast, which is more exposed to tremors, as recent earthquakes in nearby Japan could have destabilized the fault lines on the Korean Peninsula.
Samsung and SK hynix experienced temporary suspension of chip production in September a year ago when a more powerful quake struck near Gyeongju south of Pohang.
Tremors were felt in the South Korean capital Seoul, around 270km from Pohang, Yonhap added.
There were no immediate reports of any casualties or injuries.
The tremors were felt in the South Korean capital, Seoul, some 270km from Pohang, Yonhap said.The quake was recorded at a depth of 10km, USGS said, however, noting only one natural disaster in the area with a 5.4 magnitude. A third aftershock with a 3.6 magnitude was recorded later, the weather agency said.
North Korea and South Korea are located in the region known as the Ring of Fire - which extends around the Pacific Ocean and is a hotspot for natural disaster activity. As the government is working to rescue residents in the affected areas, President Moon Jae-in, who came back from his 8-day tour of Southeast Asia this afternoon, just finished holding an emergency meeting on the situation with his top aides.