Sinkholes

An Indian sinkhole that got media attention developed at Runjh in HP in November 1970. 

Sinkholes—like the one that swallowed a three-storey building in Guatemala earlier this month—usually have geological explanations, but can also be man-made. The jury’s out on the recent one. National Geographic says, ‘Instead of solid bedrock, much of Guatemala City rests atop a layer of loose, gravelly volcanic pumice that is hundreds of feet thick.’ This pumice usually hardens, but sometimes, like in this case, doesn’t. A geologist at Dartmouth College who investigated another Guatemala sinkhole in 2007 says that leaking underground pipes may have led to it.

Sinkholes appear in places where the subsurface is prone to dissolution in water. In Florida (a state prone to the incident), a sinkhole drains Lake Jackson completely about once every 25 years. 

Sinkholes form in different places for different reasons. Researchers from Pennsylvania State University studying the influence of urbanisation on sinkhole development stated that “seemingly minor activities such as replacing high grass and brush with mowed grass is observed to accelerate sinkhole development”. In the 1990s, hundreds of sinkholes formed along the Dead Sea. While researchers had noticed sinkholes there in the 1980s, the frequency in the 1990s was surprising. One theory ties it to a drop in the Dead Sea level. 

An Indian sinkhole that got media attention developed at Runjh in Himachal Pradesh in November 1970. A report by officials of the Geological Survey of India states that a deafening sound, accompanied by mild tremors, ‘woke up the inhabitants of the village. As the terror-stricken villagers rushed out of their dwellings, one of them, the owner of the revenue plot No 321, located on the south-western corner of the village, found to his consternation, a big elliptical gaping hole on his field, where, the previous evening stood a 15 metre high bamboo grove.’ 

About The Author

Rahul Bhatia