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Seoul’s Rising Sinkhole Incidents: A Seodaemun-gu Policy Response Report

Review Report April 29, 2025
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Review Point

  • Recent weeks have seen multiple large sinkholes across central Seoul, driven primarily by aging underground infrastructure and delayed government transparency. Public anxiety is growing in parallel with media coverage of high-profile collapses, highlighting the urgent need for targeted measures in Seodaemun-gu.
  • Based on documented sinkhole events near Daemyung Elementary School (d13) and data on antiquated sewer lines across Seoul (d15), along with the city’s reluctance to release a subsidence safety map (d14), there is clear evidence of systemic risk and insufficient countermeasures.

1. Recent Sinkhole Incidents in Seoul

  • Recent weeks have witnessed a troubling increase in sinkhole incidents across central Seoul, raising significant public anxiety about safety in urban areas. One notable incident occurred on March 24, 2025, when a massive sinkhole measuring 20 meters wide and 18 meters deep appeared near Daemyung Elementary School in Gangdong-gu. This event was highlighted as the largest ground subsidence reported in the city during that period, prompting urgent calls for effective governmental intervention and clearer communication with the public.

  • Following this, a series of additional sinkholes were reported, including a 40-centimeter diameter and 1.3 meters deep sinkhole near Aeogae Station on April 13, and another incident on April 15 in Jungnang District. These occurrences have primarily affected heavily trafficked pedestrian pathways and streets, further exacerbating citizens' fears and concerns about urban infrastructure reliability. According to data from the National Assembly, over 6, 028 kilometers (55.5%) of sewer pipelines in Seoul are more than 30 years old, with significant portions contributing to ground subsidence.

  • Experts have attributed these sinkhole incidents to a combination of factors, including soft soil foundations near the Han River, the aging condition of water and sewer pipes, and the high volume of traffic on urban roads. This has raised questions about the city government’s preparedness to handle such emergencies as well as the efficiency of ongoing infrastructure maintenance efforts. Public confidence is further strained by the city’s lack of transparency regarding geological risks, particularly its reluctance to disclose details such as a ground subsidence safety map, which many believe is crucial for public awareness and safety.

  • In response to these continuing challenges, the Seoul Metropolitan Government has announced plans to implement a real-time monitoring network for ground subsidence, using ground-penetrating radar (GPR) technology at key locations. However, with only seven GPR units currently available for the entire city, the measures may appear insufficient to address the immediate needs of the community. As sinkhole incidents continue to pose threats to public safety, it is imperative for the city to enhance its response strategies and improve its infrastructure evaluation protocols.

2. Underlying Infrastructure Challenges

  • Seoul's underground infrastructure is facing significant challenges as nearly one-third of its sewer system has surpassed 50 years of age. According to data from the Seoul Metropolitan Government, approximately 3, 300 kilometers (30.4%) of the 10, 866-kilometer sewer network is over five decades old. This aging infrastructure not only raises serious safety concerns but also poses increasing risks for ground subsidence and sinkholes across the city.

  • Several districts in Seoul are particularly vulnerable, with Jongno District leading with over 53.5% of its sewer lines exceeding 50 years. Other districts such as Yongsan (48.5%), Seongbuk (47.7%), and Yeongdeungpo (45.7%) also feature high percentages of outdated sewer systems. In fact, in both Jongno and Dobong districts, more than 66% of sewer pipes have been in use for over 30 years, indicating a significant portion of the city's underground infrastructure is past its prime.

  • Water leakage from these aged sewer lines is a critical factor contributing to ground subsidence, which has led to an alarming increase in sinkhole occurrences. From 2020 to 2024, 867 sinkholes were reported nationwide, with nearly half (394 cases) attributed to failures in sewer lines. This highlighting the direct relationship between failing infrastructure and public safety hazards.

  • Currently, the city allocates an annual budget of 200 billion won (approximately $147 million) to refurbish 100 kilometers of sewer lines. However, experts warn that this effort is insufficient, as approximately 150 kilometers would need to be repaired each year to adequately stabilize the risk levels associated with this aging infrastructure. To address these concerns, the city is contemplating utilizing its disaster management fund in addition to its current sewer maintenance budget. Policymakers are also in discussions with the national government for additional financial support to expedite the necessary refurbishments.

  • The introduction of ground-penetrating radar (GPR) technology has been employed to detect underground voids and prevent further incidents. However, the current limitation of only seven GPR units for the entire city restricts effective monitoring, as GPR is capable of detecting issues only up to two meters deep. This leaves deeper vulnerabilities undetected, highlighting the critical need for comprehensive infrastructure assessments.

  • With public safety at stake, Rep. Jin Sun-mi has emphasized the urgency of modernizing the city's infrastructure, advocating for greater transparency and collaborative action between local and national authorities. As these systemic issues continue to unravel, addressing the underlying infrastructure challenges is essential to safeguarding the urban environment and ensuring the safety of citizens.

3. Government Transparency and Public Concern

  • The ongoing sinkhole incidents in Seoul have foregrounded a critical issue: the transparency of the Seoul Metropolitan Government in addressing public safety concerns. In the wake of a serious sinkhole accident in Gangdong-gu, civic groups have vehemently called for the disclosure of the 'ground subsidence safety map' to foster greater public trust and awareness. However, the city's refusal to release this map, citing it as classified and irrelevant to the sinkhole incidents, has sparked considerable debate and frustration among citizens and experts alike.

  • On April 9, 2025, members of the New Seoul Preparation Special Committee addressed these concerns during a press conference, pushing for greater transparency in the face of increasing public anxiety. They highlighted that professional practices in cities like Florida and Tokyo involve openly sharing safety maps to inform residents of potential geological hazards. The committee members argue that a lack of transparency can only exacerbate fears regarding urban safety, especially in a metropolis where delicate infrastructure is aging and susceptible to hazards. It is noteworthy that more than half of Seoul's sewer pipelines are over 30 years old, a statistic that emphasizes the importance of public access to safety information.

  • Experts, including civil engineering professors, have voiced the necessity of disclosing such maps. They suggest that, should sensitive information indeed exist within these documents, redaction of critical sections could still allow for substantial information to be shared, thereby empowering citizens to understand risk levels. In contrast, the city's position—maintaining that the map's intended purpose does not align with assessing sinkhole risks—has been met with skepticism, as many contend that ongoing inspections and maintenance efforts are too often obscured from public scrutiny.

  • Moreover, in light of the Framework Act on the Management of Disasters and Safety, the committee argues that safety-related information should be invariably made public to bolster community trust and engagement. The reluctance of the government to disclose relevant safety maps sends a mixed message amid the ongoing infrastructure crises, further tightening the narrative that crucial data is being withheld from the very citizens affected by these risks.

  • The city’s current strategy includes the use of ground-penetrating radar (GPR) to assess subsurface conditions; however, limited resources currently restrict fully understanding the city's underground vulnerabilities. Only seven GPR units are available, prompting calls from policymakers and community leaders for expanded monitoring capabilities and enhanced information transparency. The path forward will require a paradigm shift in government communication to restore public trust, enhance preparedness against sinkholes, and ultimately, ensure the safety of all urban dwellers.

4. Policy Recommendations for Seodaemun-gu

  • The condition of Seoul's underground sewer and utility networks is critical as nearly a third of the system has surpassed 50 years of age. Recent data reveals that approximately 3, 300 kilometers, or 30.4%, of the total 10, 866-kilometer sewer network, is over half a century old, significantly increasing the risk of infrastructure failure and associated public safety concerns.

  • Particularly concerning are the districts with the oldest systems, where Jongno District leads with a staggering 53.5% of its sewer lines exceeding 50 years, closely followed by Yongsan (48.5%), Seongbuk (47.7%), and Yeongdeungpo (45.7%). This aging infrastructure directly contributes to ground subsidence; notably, from 2020 to 2024, nearly half (394 of 867) of the reported sinkholes nationwide were attributed to failures in sewer lines, underscoring the urgent need for immediate action.

  • Currently, the Seoul Metropolitan Government allocates a budget of 200 billion won (approximately $147 million) annually for refurbishing around 100 kilometers of sewer lines. However, experts identify this level of investment as insufficient; they estimate that 150 kilometers need rehabilitation each year to adequately mitigate risks associated with deteriorating infrastructure. Policymakers are thus exploring options to supplement this budget with funds from disaster management initiatives and discussions with the national government for additional resources.

  • To enhance monitoring capabilities, the city employs ground-penetrating radar (GPR) technology, vital for detecting underground voids that contribute to sinkholes. Nonetheless, the current limitation of just seven GPR units for the entirety of Seoul restricts comprehensive monitoring. With GPR's detection depth capped at two meters, deeper vulnerabilities remain unexamined, illustrating a critical gap in the city’s infrastructure oversight strategies.

  • In light of these challenges, it is imperative for local officials to prioritize infrastructure audits and increase transparency regarding the condition of aging sewer lines. As Rep. Jin Sun-mi has articulated, public safety cannot be left to chance, and actions must be taken to modernize the capital’s underground infrastructure. This modernization should foster joint efforts between local authorities and the national government, ensuring a proactive approach to improving public safety and urban resilience in the face of increasing risks.

Key Takeaways

  • Rising Sinkhole Incidents

  • Recent months have seen a spike in sinkhole incidents across Seoul, linked mainly to aging infrastructure. The public is increasingly anxious about urban safety, underscoring the need for stronger preventative measures in affected districts like Seodaemun-gu.

  • Aging Infrastructure Problem

  • Nearly one-third of Seoul's sewer system is over 50 years old, directly contributing to ground subsidence and sinkholes. The city allocates around $147 million yearly for repairs, but experts argue that more funding and faster action are essential.

  • Transparency Issues

  • Concerns about public safety are exacerbated by the government's reluctance to share crucial information, like the ground subsidence safety map. Greater transparency is essential to rebuild public trust and improve community safety awareness.

  • Urgent Policy Recommendations

  • Proposed actions for Seodaemun-gu include comprehensive infrastructure audits, increased sewer rehabilitation efforts, and real-time monitoring systems to mitigate risks associated with aging utilities and enhance public safety.

Glossary

  • 🔍 Sinkhole: A sinkhole is a depression or hole in the ground caused by the collapse of a surface layer, often due to the erosion of underground material. This can lead to sudden and dangerous cave-ins.

  • 🔍 Ground Subsidence: Ground subsidence refers to the gradual sinking or settling of the ground's surface. This can happen for various reasons, including the deterioration of underground pipes or natural erosion.

  • 🔍 Aging Infrastructure: Aging infrastructure refers to public utilities and structures, such as roads and sewer systems, that are old and in need of repair or replacement. Their deterioration can lead to safety hazards like sinkholes.

  • 🔍 Ground-Penetrating Radar (GPR): Ground-penetrating radar is a technology used to survey the subsurface of the ground. It helps detect issues like voids or weaknesses below the surface and is useful for assessing infrastructure condition.

  • 🔍 Public Transparency: Public transparency involves making government actions and information available to residents. It's essential for building trust and ensuring community awareness, especially regarding safety measures.

  • 🔍 Sewer Rehabilitation: Sewer rehabilitation is the process of repairing and upgrading old sewer systems to ensure they function properly and prevent issues like leaks and collapses, contributing to public safety.

  • 🔍 Urban Resilience: Urban resilience refers to a city's ability to withstand and recover from challenges such as natural disasters or infrastructure failures. It focuses on enhancing safety and reducing risks for urban dwellers.

  • 🔍 Civic Groups: Civic groups are organizations formed by community members to advocate for social, political, or environmental causes. They play a key role in raising awareness and pressuring authorities for transparency.

  • 🔍 Infrastructure Audit: An infrastructure audit is a systematic evaluation of public utilities and systems to assess their condition, identify issues, and prioritize necessary repairs or upgrades to ensure safety.

Source Documents