It is known that the three lakes on top of the Indonesian Kelimutu volcano on Flores Island change the color unpredictably – from milky white to bright turquoise and even to blood red. This phenomenon is unique.
These images were obtained with a set of OLI tools on the Landsat 8 satellite — they can observe different colors of crater lakes on three different days. All three crater lakes are located on the crest of the volcano, and the two eastern lakes even have a common crater wall.
The changing colors of the lakes became the inspiration for local folklore. Locals say that the lakes are the resting places of departed souls. Depending on the good or bad deeds committed in their lives, the dead are placed in different lakes.
The most western lake, known as Tiwu Ata Mbupu (which means “lake of old people”), is usually blue. Tiwu Nuwa Muri Koo Fai (“the lake of young men and women”) is usually turquoise. The southeast lake, called Tiwu Ata Polo (“enchanted lake”), is usually red or brown. It is believed that it is home to those who committed evil deeds. Depending on the time, colors can vary – white, green, blue, brown or black. In 2016, the lakes changed color six times.
Although it is known that lakes can be colored by different types of bacteria, changes in the colors of the lakes of Kelimutu are connected, rather, with fumaroles – cracks that are a source of hot gas emissions. Fumaroles produce a rise in water in lakes – denser mineral water rises from the bottom to the surface. All lakes have a relatively high concentration of zinc and lead.
Minerals only partly explain the phenomenon, another key factor is the amount of oxygen in the water. Like blood, the lake’s waters appear bluer (or green) with low oxygen levels. When they are enriched with oxygen, they look blood-red or even black.