Private map reveals widespread sinkhole risk in Seoul

A new study has revealed that nearly half of Seoul falls into the two lowest categories on a five-level sinkhole safety scale. The “Seoul Sinkhole Safety Map,” developed by The Dong-A Ilbo’s Hero Content Team with help from 12 experts from the Korea Underground Safety Association, found that 303 of the capital’s 605 square kilometers and 208 of its 426 administrative districts are classified as grade 4 or 5.

This marks the first time a private entity has created and disclosed a comprehensive sinkhole risk map, as the Seoul Metropolitan Government has not released its own despite having produced one. The map assesses risk levels using five categories: geological conditions, groundwater levels, subway infrastructure, past subsidence accidents, and the density of aging buildings.

International and domestic studies show sinkholes often occur in areas with soft ground near water or where underground structures were poorly backfilled. The findings are consistent with this research. High-risk zones were concentrated near the Han River and around large-scale excavation sites, including Yeouido-dong in Yeongdeungpo District and Samseong 1-dong in Gangnam District. Every site of past sinkholes that resulted in casualties or significant damage was also ranked as grade 4 or 5.

Public concern about sinkholes has grown since the 2014 collapse in Songpa District, but the government has failed to provide clear information. The Ministry of Land, Infrastructure and Transport spent 80 billion won to create an “Integrated Underground Space Map,” yet the project omitted critical data such as ground subsidence history. Likewise, the Seoul Metropolitan Government produced a five-level risk map after a 2023 sinkhole in Yeonhui-dong, Seodaemun District, but refused to release it, citing the potential for unnecessary misunderstanding and anxiety.

Experts emphasize that a low safety grade does not mean a collapse is imminent. It signals increased risk if proper safety measures are not taken during underground excavation. These areas require stricter oversight.

The refusal to disclose official data has raised concerns that authorities may be trying to avoid accountability for inadequate regulation of underground development. As cities age and infrastructure grows more complex, sinkholes pose an increasing threat. In a city like Seoul, where expansion is moving underground, transparent information is essential to ensure public safety and responsible construction practices.