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 한국을 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.