Chamoli Glacier Burst: Uttarakhand CM issues alert, what causes glacier burst?

In February 2021, a similar glacier burst incident was reported at Joshimath in Chamoli district that led to a massive flood in the Dhauli Ganga river.

source https://www.jagranjosh.com/current-affairs/chamoli-glacier-burst-uttarakhand-cm-issues-alert-what-causes-glacier-burst-1619257432-1