16 July 2002
For five years, Earthwatch
volunteers have assisted scientists exploring the geological processes of active glaciers in Iceland, including the impact of glacier outburst floods, or jökulhlaups. Last week they documented a new jökulhlaup in action and pinpointed the source of the flood, a lake beneath the glacier resulting from geothermal activity beneath the ice.
Dr. Andy Russell (Keele University) and colleagues on Earthwatch's Icelandic Glaciers project reported flying over the Vatnajokull ice cap to document a 1.5-kilometer-wide, 100-meter-deep depression, or "ice cauldron," in the glacier surface. Their observations suggest that the ice cauldron shows the rapid release of meltwater from under the glacier at this site. This has resulted in the jökulhlaup draining from the Tungaarjokull glacier 34 kilometers to the south, into the Skafta River.
"We flew over the outlets, nearly choking on the sulfurous fumes in a plane 700 feet above the jökulhlaup portals," said Russell. "The fear was that sudden drainage of a subglacial lake might have resulted in a volcanic eruption leading to more prolonged hlaup activity. So far the jokulhlaup has receded but we are on the lookout for more activity."
Iceland is the world's most volcanic island, and is covered with huge ice caps and glaciers, the recipe for some spectacular geological events. Glacier-covered volcanoes provide an ever-present threat of glacier outburst floods, and Russell indicates that Iceland is experiencing a period of increased activity.
The recent dramatic event has posed no danger to life or property, although Russell had an unconfirmed report that two Icelandic hydrologists were hospitalized after inhaling vapors from the sulfurous waters. A similar jökulhlaup in 1996 washed large quantities of ice and sediment into the Atlantic, causing significant damage to bridges, roads and power lines.
"So far this event has been restricted to the drainage of a subglacial lake, so no volcanic eruption has been noted as yet," said Russell. "Strong geothermal melting of the glacier is the probable culprit."
The downstream effects of the event are negligible so far, as the flood levels are similar to those experienced by the Skafta River every few years. However, the fact that the jökulhlaup waters came out of different glacier than they normally do has serious implications for the feasibility of hydro-electric power plants proposed for this region.
This recent jökulhlaup provides a vivid demonstration of the geological processes being studied by Earthwatch teams in Iceland. They continue to work on several recent outburst flood channels, providing greater insight into jökulhlaup processes that will help in the management of future volcano-glacial hazards in Iceland and elsewhere.
Earthwatch Institute is an international nonprofit organization which supports scientific field research worldwide by offering members of the public unique opportunities to work alongside leading field scientists and researchers. The Institute's mission is to engage people worldwide in scientific field research and education to promote the understanding and action necessary for a sustainable environment.