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Glacial lake burst or avalanche?

  • Posted By
    10Pointer
  • Categories
    Geography
  • Published
    8th Feb, 2021

Context

A part of the Nanda Devi glacier broke off in Uttarakhand's Chamoli district. Though the reason is not sure, it could be a glacial lake burst, a cloud burst or an avalanche, the impact of climate change or development.

Glacial lake outburst flood (GLOF)

  • It is a reference to flooding caused downstream due to a breach in a glacial lake.
  • Retreating glaciers result in the formation of lakes at their tips, called pro-glacial lakes, often bound only by sediments and boulders.
  • If the boundaries of these lakes are breached, it can lead to large amounts of water rushing down to nearby streams and rivers.
  • GLOF events impact depends on the size of the proglacial lake that burst, and location.

Proglacial lakes

  • A proglacial lake is a lake formed by
    • damming action of a moraine during the retreat of a melting glacier
    • a glacial ice dam
    • by meltwater trapped against an ice sheet due to isostatic depression of the crust around the ice.

Reasons behind GLOF

The breach can be caused by several reasons:

  • Erosion
  • The buildup of water pressure
  • Avalanche of rock or heavy snow
  • Earthquake or Cryoseism
  • Volcanic eruptions under the ice.