Summary
In a surprising revelation from Greenland’s ice streams, researchers have uncovered the occurrence of tiny ice quakes that could reshape our understanding of sea level rise. These hidden quakes, triggered by volcanic particles buried deep beneath the ice, challenge existing computer models that predict the dynamics of ice flow.
Ice streams are frozen rivers that move ice from Antarctic and Greenland ice sheets to the sea. Changes in these ice streams can significantly impact sea levels. Researchers use computer models to predict future sea levels, but these models are limited due to difficulties in directly measuring glacial properties. Satellite data reveals that these models have inaccuracies, leading to uncertainties in estimating ice loss and sea-level rise.
Researchers found something unexpected that causes ice streams to move deep within the ice streams. For the first time, an international team of researchers -led by ETH professor Andreas Fichtner – has shown that countless tiny ice quakes occur in one of Greenland’s mightiest ice streams.
Researchers discovered numerous weak quakes within ice streams. Triggering one after another, these tiny quakes spread over hundreds of meters, explaining the discrepancies between simulations and satellite measurements. This finding will improve future ice stream simulations.
Fichtner states ice streams move with a constant stick-slip motion, unlike viscous honey. This new understanding will make sea level change estimates more accurate.
The discovery of ice quakes within ice streams was previously unnoticed because of a layer of volcanic particles located 900 meters below the ice surface. These particles, formed by Mount Mazama’s eruption 7,700 years ago, prevent the quakes from reaching the surface.
The quakes start from volcanic impurities like sulfates, which traveled globally and settled on the Greenland ice sheet, reducing the ice’s stability and causing micro-fissures.
Fichtner was surprised by the connection between ice stream dynamics and volcanic eruptions.
Researchers discovered ice quakes within ice streams by inserting a fiber-optic cable into a 2,700-meter-deep borehole. The borehole, drilled by the East Greenland Ice-core Project (EastGRIP), allowed researchers to record seismic data for the first time.
The research station and borehole are located on the North East Greenland Ice Stream (NEGIS), significantly contributing to rising sea levels. Ice quakes were found to occur frequently, suggesting they might happen in ice streams worldwide. To confirm this, more seismic measurements will be needed in other boreholes.
Journal Reference:
- Andreas Fichtner, Coen Hofstede, Brian Kennett et al. Hidden cascades of seismic ice stream deformation. Science. DOI: 10.1126/science.adp8094
Source: Tech Explorist
