People’s anxiety grows as series of sinkholes occur in Seoul

A road in front of Eonju Station in Gangnam-gu, Seoul, is partially blocked after land sinking occurred on August 31. Yonhap News

Even before the shock of an accident in which two people were seriously injured when their car fell under the ground caused by a sinkhole in Yeonhee-dong, Seodaemun-gu, Seoul, a series of sinkholes have been found in various parts of the city center, causing public unrest. There is a high demand for systematic and effective pre-inspection to quell civil unrest and damage.

On September 1, Mr. Noh (30), who works in Jongno-gu, Seoul, said his fears grew when he heard that sinkholes were found on the road near Jongno 5-ga Station on Subway Line 1 the day before. "I don't think I can let my guard down anywhere because sinkholes were found here and there in the city. It's even scarier because I can't avoid sinkholes by being careful by myself.”

According to police and fire authorities, a 40-centimeter-wide, 40-centimeter-long and 1.5-meter-deep hole was found on the road from Jongno 5-ga Station to Jongno 3-ga Station at around 4 p.m. on August 31. On the same day, a road subsidence also occurred on the road from Eonju Station on Subway Line 9 to Hakdong Station on Line 7 in Yeoksam-dong, Gangnam-gu, and traffic was partially blocked. This comes two days after a 6-meter-wide, 4-meter-long, and 2.5-meter-deep sinkhole was found in Seodaemun-gu.

The risk of land sinking is said to increase when the inflow of groundwater increases rapidly due to heavy rain in summer, or when the sewer pipes that carry rainwater are old and leak. As the viscous water flows through the ground, it sweeps away sand and gravel, causing holes to form.

Seoul has been using Ground Penetrating Radar (GPR) to regularly inspect roads since the land sinking was found on the Seokchon underpass in 2014. However, it has been pointed out that GPR has limitations because it can detect only 3 to 4 meters below the surface. The Seoul Metropolitan Government said on August 29 that it inspected the roads in Seodaemun-gu where a sinkhole was found in May but did not find any empty spaces. Park Chang-geun, a civil engineering professor at Catholic Kwandong University, pointed out, "Sinkholes can occur even at 7-8 meters underground, but they may not be detected with Seoul's GPR equipment that can detect only 3-4 meters."

Experts advised that the city should more practically prepare for sinkholes in advance by introducing specialized personnel and equipment. “Sinkholes cause tremendous damage once they occur, so the city needs to prepare more equipment that can thoroughly conduct underground investigations,” said Cho Won-cheol, professor emeritus at Yonsei University's School of Social and Environmental Systems Engineering. “In particular, in February and March, when the ground is hard, and in August and September, when the ground changes due to summer rains, it needs to conduct regular investigations to see if there are holes and reinforce them.”

Some also say that quality control should be thoroughly carried out when underground construction is carried out in the city center. "The quality control of the soil brought out during underground excavation works and the installation of barrier walls nearby must be done properly,” Park said.

※This article has undergone review by a professional translator after being translated by an AI translation tool.