With modern technology, researchers are capable of monitoring earth movement in real-time. But the prospect of uncovering why landslides occurred many thousands of years ago is a much more abstract notion.
As reported on the science website Phys.org, Geologists Adam Booth and Halldór Pétursson studied the mountainous terrain around Eyjafjörður, hoping to discover what caused ancient landslides following a period of deglaciation approximately 13000 years ago.
What caused ancient landslides?
676 post-glacial bedrock landslides in north-central Iceland were analysed as part of the study. Much of the technical work involved using 2-m resolution digital elevation data generated from optical stereo satellite imagery.
Their research focused on tertiary flood basalts, somewhere between 2 and 30 meters thick, mixed with sedimentary and volcanic deposits. It was found that the landslides did not spread evenly across the 268 sq km zone designated for the study, but instead clustered, particularly in elevated areas thick with permafrost.
By comparing erosion levels with those measured at mountains nearby, it was found that ancient landslides at Eyjafjörður were actually most likely triggered by melting permafrost. This would mean that the landslides did not occur immediately following deglaciation, but thousands of years afterwards.
Published in the prestigious Journal of Geophysical Research: Earth Surface, these findings have important implications as to the future. Namely, during this period of a warming climate, how permafrost degradation might affect areas already prone to landslides.
