A car is trapped in a 2.5-meter-deep sinkhole on a road in Seoul, Thursday. This accident seriously injured an elderly couple. Yonhap

Drivers and road management authorities in Seoul are increasingly alarmed as a sinkhole swallowed a car on Thursday and a subsidence of a road was detected nearby one day later.

The recurrence of such incidents has sparked fears about the safety of the city's roads and the potential for more severe accidents at any time and place.

On Friday, the road management authorities of the Seoul Metropolitan Government said its officials found a slight sinkage in a road in Yeonhui-dong in western Seoul's Seodaemun District at around 8:40 a.m.

The subsidence was located only about 100 meters from the site where a 6-meter-wide, 4-meter-long and 2.5-meter-deep sinkhole swallowed a vehicle the day before. The accident resulted in serious injuries to the driver, an 82-year-old man, and his 79-year-old wife. While the driver suffered broken ribs, his wife was found in cardiac arrest but saved through CPR, although she still remains unconscious in intensive care.

After the problem in the road was found on Friday, the authorities and police restricted traffic in the area and initiated an investigation to determine the cause. They said it is still unclear whether the two road problems are related and from the same cause.

The authorities and experts are coming up with various potential causes, such as aging drain pipes underground, construction to install a rainwater drainage pipeline that is taking place about 170 meters from the accident site, and soil erosion caused by heavy rainfall.

The city said it is searching for underground holes regularly and in its May investigation, no holes were found in the area around the sinkhole.

A section of a road in western Seoul's Yeonhui-dong is closed as the authorities investigate a subsidence of the road there, Friday. Yonhap

There were also concerns that the sinkhole could have led to a major disaster as a gas pipeline and water supply pipes run directly below the affected area. However, no gas pipe damage or leaks were reported.

"We are taking this matter very seriously," a city government official said. "Ensuring the safety of our roads and preventing future accidents is our top priority."

This series of accidents has led to growing public anxiety, particularly in neighborhoods where construction projects are underway. Residents are demanding more thorough inspections and stronger safeguards to prevent another potentially life-threatening event.

"The sinkhole will become a serious issue if more are detected. It already occurred in Jamsil and now in Yeonhui-dong. There's no guarantee it won't happen in my neighborhood," a woman in her 40s, identified with the surname Chung, said.

According to data from the land ministry released by Rep. Hwang Hee of the Democratic Party of Korea, a total of 957 sinkholes were reported nationwide between 2019 and 2023.