Not a geologist, but essentially there is a layer of clay, called quick clay, that suddenly turns to soup. The clay was originally deposited in coastal waters and compressed by glaciers. When the glaciers melt, the land rebounds upwards and this marine clay deposit ends up above sea level. At this point the salt that added stability to the soil structure begins to leech out, leaving only the clay particles stacked like a house of cards.
When the clay is disturbed by heavy rain, earthquake, or even construction it can suddenly liquify. This is what causes the ultra low angle landslide. Quick clay is only found in places far north like Alaska, Norway, Russia, Canada, etc.
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u/Ikono_0 May 02 '25
Geologists gather here, I need the what and the why?