When glaciers and ice sheets soften, they are able to destabilize slopes and reactivate faults, which in flip can set off landslides and reshape the outside of Earth over lengthy classes of time. Researchers can track some places in actual time to resolve which mixtures of things result in landslides, however figuring out what induced landslides hundreds of years in the past is tougher.
Adam Sales space and Halldór Pétursson appeared to the slopes round Eyjafjörður, a fjord in north central Iceland, to discover the triggers at the back of landslides that befell within the wake of the retreat of the Icelandic ice sheet about 13,000 years in the past. The paintings is revealed within the Magazine of Geophysical Analysis: Earth Floor.
The workforce mapped 676 postglacial, deep-seated landslides across the fjord the use of stereo satellite tv for pc imagery with 2-meter solution. The bedrock within the find out about space is composed basically of Tertiary flood basalts between 2 and 30 meters thick, interlayered with sedimentary and localized volcanic deposits. They discovered that the landslides weren’t unfold lightly around the 268-square-kilometer find out about space however as an alternative clustered in spaces inside of 2.6 kilometers of primary Tertiary bedrock buildings and alongside the margins of high-elevation permafrost.
Spaces the place landslides befell just lately have a tendency to have sharply outlined floor options, while older websites are frequently smoother as a result of erosion. So the researchers used the roughness of the landslide deposits, calibrated to 17 already-dated landslides from simply west in their find out about space, as a proxy for figuring out the timing of the landslides round Eyjafjörður.
They discovered that about 90% of landslides within the Eyjafjörður space didn’t happen in an instant following deglaciation. As a substitute, they have been behind schedule by way of a number of thousand years, till permafrost started thawing.
The researchers say their findings point out that thawing permafrost used to be crucial set off of landslides in Eyjafjörður. They be aware that this trend could have necessary implications for long term landslides as warming continues and permafrost degrades.
Additional info:
Adam M. Sales space et al, Permafrost and Structural Controls on Holocene Bedrock Landslide Prevalence Round Eyjafjörður, North‐Central Iceland, Magazine of Geophysical Analysis: Earth Floor (2025). DOI: 10.1029/2024JF007933
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Thawing permafrost helped set off historic Icelandic landslides, new analysis displays (2025, January 22)
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