A previously unknown phenomenon discovered at the bottom of the ice transmission of the Greenland ice layer will change the way scientists model ice and sea level level.
The ice currents of Antarctica and Greenland contribute to the main taxpayers to the increase in sea level, transporting ice from the ice layers in the sea to the sea. Then, precisely predicting its behavior in a changing climate is of the utmost importance.
Currently, the simulations of the movements of the ice current assume that they flow slowly and constantly as thick honey. But the results of these models are not aligned with satellite measurements.
Now, a team of researchers, including one from the National University of Australia, discovered that ice currents also move with a constant sliding motion.
This is driven by innumerable weak earthquakes within the ice that are triggered and spread more than hundreds of meters.
They found the earthquakes drilling a well of almost 3 km in the ice current of the northeast of Greenland (Negis) and lowering a 1.5 km fiber optic cable to detect seismic data using the distributed acoustic detection (DAS).
He investigation It is published in the magazine Science.
“The fact that we have now discovered these ice lands is a key step to obtain a better understanding of the deformation of ice currents in small scales,” says Olaf Eisen of the Alfred Wegener Institute in Germany, one of the study co -authors .
The earthquakes are the origin of the fault planes between ice crystals in the nuclei taken from great depths, which have been known by scientists for decades, but remained inexplicable so far.
Ice earthquakes cannot be observed on the surface due to a layer of volcanic particles located at 900 m deep. The analysis of the ice core showed that these volcanic particles originate in a massive eruption of Mount Mazama 7,700 years ago, in what is now the American state of Oregon.
The triggers of ice earthquakes also date back to volcanic eruptions.
The traces of sulfate impurities that entered the atmosphere in volcanic eruptions and were deposited in the Greenland ice layer in Nevada reduce the stability of the ice and favor the formation of micro fissures.
“We were surprised by this previously unknown relationship between the dynamics of an ice stream and volcanic eruptions,” says Professor Andreas Fichtner of Eth Zurich in Switzerland, lead author of the article.
As ice earthquakes occur frequently in a wide area in researchers, Fichtner believes that it is also plausible that they occur in ice currents everywhere, all the time.
To verify this, they plan to take seismic measurements in other wells.
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