In the early hours of April 13, a large sinkhole measuring 5 m wide, 3 m long, and 5 m deep appeared near the construction site for the Sasang–Hadan subway line in Busan’s Sasang district. A similar sinkhole occurred at the same site last September when two trucks fell 8 m into the ground. On the same day, a smaller sinkhole measuring about 40 cm wide and 130 cm deep was discovered next to Exit 2 of Aeogae Station in Mapo district, western Seoul. Just two days earlier, on April 11, a tunnel construction site for the Shinansan Line in Gwangmyeong, Gyeonggi Province collapsed, causing part of a six-lane road and nearby construction structures to cave in.
These incidents occurred less than 20 days after a large sinkhole opened on March 24 in Myeongil-dong, Gangdong district, Seoul. The sinkhole, which measured 18 m wide, 20 m long, and 18 m deep, resulted in the death of a motorcyclist in his 30s. The fact that so many incidents are occurring in spring, well before the summer rainy season when heavy rain typically weakens the ground, raises growing concerns about ground stability.
According to the Ministry of Land, Infrastructure and Transport’s Underground Safety Information System, 1,337 sinkhole incidents were reported between 2018 and 2024, an average of about 200 per year. The causes vary, including leaks from aging water and sewage pipes, stress from subway and road construction, and substandard construction work. Much of South Korea’s underground infrastructure was built during the country’s rapid development in the 1970s and 1980s and is now showing its age. In Seoul, nearly 27% or about 1,850 km of the city’s 6,863 km of roads are considered vulnerable to subsidence.
Preventing sinkholes requires careful and systematic management of underground infrastructure, along with reliable early warning systems. In areas with aging systems, repairs must be carried out promptly. Construction zones should be regularly checked for leaks and ground stability. Strong oversight is also essential throughout underground construction, from tunneling methods and soil assessments to waterproofing work. Sinkholes are not random accidents. They are a growing public safety risk. The danger beneath our feet can no longer be ignored.
