Land subsidence

Context: The exact reason behind Joshimath land subsidence is still unknown but experts cite unplanned construction, over-population, obstruction of the natural flow of water, and hydel power activities as possible causes.

About Land Subsidence:

• According to the National Oceanic and Atmospheric Administration (NOAA), subsidence is the sinking of the ground because of underground material movement.
• Reasons can be manmade or natural:
  • removal of water, oil, or natural resources, along with mining activities
  • Earthquakes
  • Soil erosion and
  • Soil compaction

Reasons behind Joshimath subsidence:

• unplanned construction,
• over-population,
• obstruction of the natural flow of water and hydel power activities.
• the area is a seismic zone, which makes it prone to frequent earthquakes.
• the subsidence in Joshimath might have been triggered by the reactivation of a geographic fault —
  • defined as a fracture or zone of fractures between two blocks of rock — where the Indian Plate has pushed under the Eurasian Plate along the Himalayas.

Source:   Indian Express