Frost quakes are non-tectonic seismic events that occur when the freezing of water in saturated soils or rocks causes a sudden release of energy in the form of quakes.
On 6 January 2016, a swarm of these quakes shook the sub-Arctic region of Oulu in central Finland, leading to ruptures in soil, building foundations and roads.
Researchers, including those from the Geological Survey of Finland, have now shown that the frost quakes are related to a “rapid decrease in air temperature” from -12C to -29C that create thermal stress in frozen soil, buildings, houses and roads, causing huge cracks.
Previous studies and climate reports have shown that global heating has a disproportionate effect in the Arctic, which is warming significantly faster than most other places on Earth.
Scientists, however, said the consequences of such an uneven warming of the planet, especially in the Arctic as well as sub-Arctic environment, are not well understood.
While models to analyse and predict changes in snow cover and snow melt each year have been developed, the effect of such warming on frozen soil and related phenomena such as frost quakes remain unclear, according to the study, presented recently at the 2023 European Geosciences Union General Assembly.
Compared to earthquakes in seismology, the mechanism and effects of frost quakes, which usually occur at random, are “much less studied”, researchers said.
They said a methodology to accurately predict the occurrence of these quakes is particularly missing.
Part of the reason is that these rare weather phenomena are less predictable and occur at rarely instrumented locations.
Recently, reports of frost quakes causing damage to pavements, roads and buildings have emerged from different parts of the world, including from Finland, Canada and the US, with links also found between air temperature and the phenomenon.
In the new study, the connection between frost quakes and thermal stress, a function of temperature that can be measured or calculated, was analysed.
Scientists first calculated snow depth, snow melt rate and soil temperature at different depths in soil using a model.
Using this, they found that a rapid decrease in temperature can cause a thermal stress that is higher than the toughness and strength of soilâice mixture.
“We show that origin of frost quakes was related to rapid decrease in air temperature from -12C to -29C that created thermal stress in frozen soil and roads which could not withstand the stress,” scientists wrote in the study.
The findings suggested that frost quakes may be tied to climate change, the worsening intensity of which could make such seismic events more frequent.