The purpose of this website is to disseminate information on natural hazards in Iceland related to glaciers.
The site is maintained by the Geophysics Division of the Science Institute.

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Jökulhlaups

Diffrent sources
of jökulhlaups:
 

"Jökulhlaup" is an Icelandic word meaning a sudden outburst flood in a glacial river caused by the drainage of an ice-dammed lake, regardless of whether the lake is ice-marginal, subglacial or supraglacial.

In this website the acronym GLOF is used for  jökulhlaups caused by the drainage of ice-marginal lakes. 

Subglacial geothermal heat or volcanic activity usually leads to an increased ice-melting rate, and the meltwater either drains away immediately or accumulates in a subglacial lake. In such a lake the water level constantly rises and finally reaches a critical level and a jökulhlaup occurs. These kinds of jökulhlaups are the most hazardous. The best known recent example was from lake Grímsvötn in November 1996.
 

• Drainage of
  ice-marginal
  lakes (GLOF)

• Drainage of
  subglacial lakes.

• Jökulhlaups accompanied
  by subglacial volcanic eruptions.

                                                  Photo: Helgi Björnsson, Nov 1996