A rock fell from Kuravan Hill, one of the two hills connecting the Idukki arch dam, early on Friday, because of rock weathering, a phenomenon that results in the rock falling on the foothill and disintegrating into pieces, according to the preliminary examination by the Dam Monitoring and Research Station, Vazhathoppe.
A senior engineer of the Kerala State Electricity Board (KSEB) told The Hindu on Saturday that though Kuravan Hill faced more threat of rock weathering, Kurathi Hill too had seen similar occurrences, in a small scale, in the past. In 2006, a few sheep grazing on the foothill of Kuravan Hill below the arch dam were killed in rock weathering.
The engineer said that geologists were studying the incident to find permanent remedial measures.
Other factors
As time passes, all rocks decay and disintegrate and there are certain other factors, including climate change, that impact rock weathering. To resist rock weathering, the KSEB had in the past removed loose soil and rocks that were exposed. According to geologist Raman Namboodiri, changes in climatic conditions result in chemical changes, leading to rock weathering.
Even mighty rocks fall due to chemical process caused by extreme changes in night and day temperatures.
The rain water inside the cracks of rock picks up acid from the air and soil. The rock slowly gets corroded.
The decomposing minerals within the rock also act as agents for the decay. Once the granite is exposed after removal of the corroded rocks, that disintegrates in the same chemical process.
In countries with alternately hot days and cold nights, the water stored at the cracks freeze to ice and it expands, forcing the rock apart.
