Ice streams move unpredictably due to hidden quakes

Often thought of as frozen rivers, the vast ice streams of Greenland and Antarctica serve a pivotal role in our climate system. Like sluggish streams of frosty honey, they ferry ice from the heartland sheets to the seas.

The steady movement of ice streams has long been considered predictable, with models assuming a continuous and gradual flow.

However, new findings suggest that beneath their seemingly smooth surface, these icy giants behave in ways that are more complex than we imagined.

Rethinking ice movement

Previously, scientists used computer simulations to estimate how ice streams could impact sea-level rise.

These simulations have always been underpinned by a simple concept: the ice steadily and slowly flows into the sea.

But satellite measurements have painted a different picture, revealing noticeable shortfalls in these simulations, leading to inaccurate results in how much ice is being lost, and consequently blurring our projections on sea-level rise.

Behavior of ice streams

A team of researchers at ETH Zurich, led by Professor Andreas Fichtner, has discovered a startling fact about the behavior of ice streams.

Hidden deep in the icy belly of these streams, countless weak quakes are constantly unfolding, triggering each other and extending over hundreds of meters.

“The assumption that ice streams only flow like viscous honey is no longer tenable. They also move with a constant stick-slip motion,” said Fichtner.

As these findings are integrated into future simulations, experts may be able to better predict sea-level changes.

The mystery of fault planes

Interestingly, the discovery also resolves a longstanding puzzle about fault planes found between ice crystals in deep ice cores. These fault lines, the fallout from tectonic shifts, have puzzled scientists for years.

“The fact that we’ve now discovered these ice quakes is a key step towards gaining a better understanding of the deformation of ice streams on small scales,” noted study co-author Olaf Eisen, a professor at the Alfred Wegener Institute.

A volcanic twist

These ice quakes have remained unnoticed due to a layer of volcanic particles, situated 900 meters under the ice surface.

The volcanic particles – traced back to a massive eruption of Mount Mazama about 7,700 years ago – block the quakes from reaching the surface.

Fichtner also pointed out that the ice quakes start from impurities in the ice, which are actually remnant sulphates from volcanic eruptions, thus highlighting an unexpected connection between volcanic eruptions and ice stream dynamics.

Revealing hidden seismic activity

The experts unraveled the mystery of ice quakes using a fiber-optic cable inserted into a 2,700-meter borehole, recording seismic data from within a massive ice stream. They used a borehole drilled for the East Greenland Ice-core Project.

The team dropped a fiber-optic cable deep into the borehole, capturing data from within the ice stream continuously over a 14-hour period.

The prospect of ice quakes is not just limited to the data site. Fichtner believes that they likely occur in ice streams globally. While verifying this will require further seismic measurements in other boreholes, the team has already started working on it.

This research provides a fresh perspective on the ice-stream dynamics that play a crucial role in shaping our planet’s future.

Rethinking ice stream models

The discovery of tiny ice quakes will reshape how scientists model ice streams and their role in global sea-level rise.

Traditional simulations assumed a steady, smooth flow of ice, but incorporating stick-slip motion into these models could refine predictions and provide more accurate assessments of future ice loss.

By integrating real-time seismic monitoring with satellite data, the researchers aim to build a more comprehensive understanding of ice stream dynamics.

As the team continues to expand their studies to other ice streams around the world, these findings could mark a turning point in climate science, offering better tools to anticipate and mitigate the effects of a warming planet.

The full study was published in the journal Science.

—–

Like what you read? Subscribe to our newsletter for engaging articles, exclusive content, and the latest updates. 

Check us out on EarthSnap, a free app brought to you by Eric Ralls and Earth.com.

—–