On March 25, 2025, a large sinkhole occurs near the entrance of Daemyung Elementary School in Gangdong-gu, Seoul, while the fire department and police are controlling the area. /Courtesy of Chosun DB

The Seoul city government announced that it will disclose the areas surveyed with ground penetrating radar (GPR) to ensure citizens do not feel uneasy about the phenomenon of sinkholes.

The ‘GPR survey map’ can be accessed on the Seoul Safety Nuri (safecity.seoul.go.kr) website by navigating to ‘Frequently Asked Information’ or by selecting ‘Safety Information Map’ → ‘Ground subsidence’ at the top.

Previously, the Seoul city government has been publishing the results of special GPR inspections in the form of posts on the Seoul Safety Nuri safety data room since the sinkhole incident in Myungil-dong, Gangdong-gu, in March.

The GPR survey sections will be marked with lines on the map, and by selecting those lines, users can check detailed information such as the investigation period and extension. Sections where no empty space was found underground will be marked in blue, while those where it was found will be marked in purple. If empty space is discovered, detailed information such as the exact location, size, and measures taken will also be provided.

Seoul Safety Nuri screen.

The Seoul city government will initially release the results of special GPR inspections conducted from January to early May on 364 sites along a 350 km stretch. This includes the construction sites for subway Line 9 phase 4, Dongbuk Line, Yeongdong-daero, Shin Ansan Line, and the Metropolitan Express Rail (GTX)-A, as well as 50 sites requested by autonomous districts and 309 excavation sites.

The city has completed emergency repairs on 63 underground empty spaces that were discovered in advance during the special inspections. This includes 33 construction sites for railways, with 32 in the Shin Ansan Line segment and 1 in the Dongbuk Line segment, as well as 12 excavation sites and 18 areas requested by autonomous districts.

The city plans to strengthen GPR surveys at the autonomous district level in the future. The expense of the district’s own inspections will be shared equally between the city and the districts. To this end, 1.5 billion won will be supported by the city.