Sekiheki (Red Cliff)
True to its name, this sheer cliff located on the northern coast of Chiburijima Island is splattered with bright red streaks. This red colour is related to the specific nature of the eruption that occurred here.
The rock turned red as a result of the composition and manner in which magma erupted here. Magma with high gas and iron content erupted from the volcano at very high temperature, causing it to erupt in in splatters. The iron content in these splatters of magma oxidized upon contacting the air, causing the rock to turn red. This magma piled up around the mouth of the volcano and can be seen in the cross-section of the cliff that has been eroded away. The higher the temperature of the erupted magma is, the faster the chemical reaction of the iron. Magma that erupted in splatters oxidized quickly, and the entire body of the magma turned red, despite the short time that it was flying through the air.
You can observe the evidence of repeated eruptions that occurred in the layered pattern of the cross-section of the cliff. The grey or black sections of the cliff were created by the same type of rock, however did not turn red. This is because the magma that formed this rock did not erupt in splatters, but flowed from the volcano more slowly. When this series of volcanic eruptions ceased, further volcanic activity of a different geological composition occurred, creating the long pale grey-coloured pillars that intrude vertically through the rock.
This sequence of events resulted in the various colours of this cliff. It is one of the most stunning cliffs of the Oki Islands and a symbol of Chiburijima Island.