Straddling the border between North Korea and China is a still-active volcano, Mount Paektu. Its last eruption was in 1903 and scientists consider that another one could be imminent, based on a trend of eruptions roughly 100 years apart. The crater lake, Lake Chon (‘Heaven Lake’) was formed in the 946 AD eruption.
After the deforestation of Rapa Nui, and the destruction of the moai, probably as a result in part at least of war between the tribes, the people needed to believe in something; if their ancestors could no longer protect them, who would? The answer was, one of their own.