400 tons of rock collapses in the blink of an eye... tourist spot Kameiwa = South Korea

The head of Kameiwa Rock, a famous tourist destination in Ulleung County, North Gyeongsang Province, South Korea, completely collapsed, injuring four tourists.
On the 2nd, the YouTube channel "OK Car Night Nationwide Tour" posted a video that captured the moment Kameiwa collapsed around 6:50 a.m. on that day.
I uploaded it. The video shows Kameiwa's head cracking and falling down in an instant. Tourists can be seen running away, surprised by the sudden collapse of the rock.
The accident left four people in their 20s and 30s camping near Kameiwa with serious and minor injuries. One woman in her 20s was diagnosed with a skull fracture and was referred to Dr. HYERI.
The other three people were taken to the hospital with minor injuries. A vehicle parked near the rock was also partially damaged.
Meanwhile, witnesses heard a ``gurgling'' sound just before Kameiwa collapsed.
A few seconds later, the building collapsed with a ``ding'' sound. Approximately 400 tons of rock fell at once.