Mount
Kelimutu, with its
multi-colored crater lakes, is the amazing natural phenomenon in central Flores
Island of Indonesia. Kelimutu is a passively degassing stratovolcano capped by
three crater lakes containing exotic fluids and whose physico-chemical expressions
have changed dramatically through the years. Three crater lakes are located on the eastern summit of
Kelimutu. Each of the lakes has a distinctive physical structure, a unique
geochemical and hydrothermal regime, and a particular historical sequence of
color changes controlled by changes in physico-chemical conditions. The visitor is never quite sure what color the lakes will be
when they reach the top as they vary significantly. Unlike other crater lakes
where the color variation can be predicted, this is not the case with these
three lakes. The colors that you can see here are blue, green and black (and
they predominate) yet the lakes also change to white, red and blue too.
The first lake is named Tiwu Ata Mbupu (lake of the
ancestors’ souls ); the second is named Tiwu Nuwa Muri Koo Fai (lake of young
people’s souls); and the third is called Tiwu Ata Polo (lake of evil spirits).
Tiwu Ata Mbupu, is the western-most lake and is structurally
different from the other two in that the pit crater it is in is itself located
in the center of a larger crater. Small landslides constantly add to the steep
rubble slopes along the lake’s shore, and large boulders periodically drop into
the lake. TAM’s shoreline is coated with a film colored in different shades of
red, orange, and yellow depending on how thick it is. Gypsum crystals grow in
the cracks of the crater wall in the first few meters above the prosent water
surface.
Tiwu Nua Muri Koo Fai, is adjacent to Tiwu Ata Polo and is
the deepest lake. A sizable tear in the western wall was the location of a
pre-1929 breaching and overflow event. Subaerial fumarolic or hydrothermal
activity is implied by a large thermal plume in the center of the lake which
slowly convects the water. A fresh supply of yellow froth is brought up by the
plume and pushed out toward the crater wall. A particularly large cover of this
froth has accumulated at the base of the north wall. During rainstorms the
froth is scattered by inflowing water and landslides, though some of it may be disappearing
altogether.
Tiwu Ata Polo, lies on the southeastern side of the volcanic
peak. A thermal plume in the northwest part of the lake indicates underlying
subaerial fumarolic or hydrothermal activity. A white froth is present on the
lake’s surface around the plume when the convective activity momentarily
increases. Rock debris is often carried into Tiwu Ata Polo during rainstorms by
water draining the volcano summit around the lake. Two peaks abutting the
crater rim help stabilize the east and northeast crater wall, while further
around to the southeast a dip suggests a possible one-time overflow outlet.
Such an outlet would have fed the river Ria Mbuli, whose upland source is in
that area.
Tiwu Ata Polo and Tiwu Nua Muri Koo Fai are only separated by
a steep parabolic partition that arcs down to a minimum height of ~35m above
the surface level of the lakes. Many Indonesian guidebooks describe the vibrant colors of
the Kelimutu lakes as resulting from the minerals in the lakes. While this is
partly correct, the most important determinant of color in the lakes is oxygen.
Just like your blood, when the lake waters lack oxygen they look green.
Conversely, when they are rich in oxygen, they are a deep red to black.
Source : http://www.lovelynature.net
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