The long-running mystery of glacier lakes includes floods or “jockeys” that come out of glaciers or ice caps suddenly and unexpectedly. Scientists have long studied the evolution of these floods, some of the largest on Earth.
These floods affect the movement of some glaciers and are a major crisis in Iceland. And the method and timing of the onset of these floods are not understood.
A new study led by Monoa astrobiologist and earth scientist Eric Gadoz of the University of Hawaii has solved the mystery.
In June 2015, an unexpected series of events revealed how the flooding began. That summer, scientists dug a hole in one of Icelandic lakes to study its microbial life. While collecting samples through the borehole, the team observed a downward flow in a hole.
The flow was so strong that scientists almost lost their sensors and sampling devices in the hole.
Gadoz said, “We speculated that we accidentally connected the body of water inside the glacier to the lake below. The amount of water in that lake was flowing fast. “
A few days later, after the team left the glacier, the lake flooded. Fortunately, the flooding was low, and the Icelanders have an extensive early warning system on their rivers, so no one was hurt in the incident, and no infrastructure was damaged.
Scientists used a computer model of the current flowing through the hole and the effect on the computer pond to show that it could trigger the flood.
Gadoz said, “We discovered that glaciers could contain small bodies of water above the melting lakes of summer. If this reservoir is hydraulically connected to the lake, the pressure in the lake increases and water starts leaking out from under the glacier. “
When the team made an artificial connection to the lake in 2015, natural connections are formed when water from rain or melting ice accumulates in the curves. The pressure eventually cracks through the glacier towards the lake. This discovery provides a new understanding of how this flood can start and how it depends on the weather and season.
Icelandic collaborators continue to research the phenomenon using radio echo-sounding to find underwater reservoirs and study large lakes beneath it.
Journal Reference:
- E. Gados et al., È press noos, led é ledge: a human – triggered jekulhl from p from f subglacial lake, geophysical research letters (2020). DOI: 10.1029 / 2020GL089876
