What do you understand from land subsidence? Explaining various reasons behind land subsidence. Recommend measures to arrest the calamity.

The recent news of land subsidence cases in Joshimath, Uttarakhand has highlighted the calamity. Land subsidence refers to the sinking of land due to underlying factors. Reasons of land subsidence: Natural factors: - Build up on seismically active terrain - Land slide prone area - Presence of aquifer underneath Anthropogenic factors: - Unplanned construction — build up of pressure on land - Heavy construction and demolition activity — disturbing the land - Fractures in aquifer leading to sinking

Measures to arrest the calamity: i Planned construction — limiting the number of households. ii Surveying and mapping of land — hazard zone maps iii Building laws — light weight materials usage. iv Proper drainage v Use of scientific methods for development projects. eg Drilling instead of using detonators for making tunnels. MC Mishra committee guidelines along with collaboration of institutions such as ISRO, GSAT to be needed to arrest the calamity