A rare weather phenomenon called "frost quakes," which struck Finland in 2016, is likely becoming more common due to the climate crisis.

Frost Quakes Triggered by Cold Waves Cause Non-Tectonic Ground Shaking; Seismic Activities Pose Threats on Northern Regions
(Photo: Wikimedia Commons/ Sharon Mollerus)

Understanding Frost Quakes

Frost quakes refer to seismic events with frequencies ranging from 10 to 20 Hz and waveforms that resemble those of tectonic events—also known as ice quakes or cryoseism; they occur when the freezing of water in saturated soils or rocks leads to a sudden release of energy in the form of quakes.

This phenomenon is most common during extreme winter conditions when wet, snow-free ground rapidly freezes. Roads and other places cleared of snow in winter are more vulnerable to this seismic event, which can also potentially damage infrastructures. As a result, frostquakes must be considered in seismic hazard assessment.

Water can accumulate in the ground during heavy rainfalls in autumn or when snow melts during warm winter weather. As it rapidly freezes and expands, the stored water causes cracks and shaking of the ground. People can also feel this when it occurs in populated areas, especially if specific noises accompany it.


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A Threat in the Arctic

On January 6, 2016, the sub-Arctic region of Oulu in central Finland was shaken by a swarm of ice quakes, which led to ruptures in soil, roads, and building foundations. There have also been recent reports of frost quakes causing damage in different parts of the world, such as Canada and the US.

Earlier studies and climate reports suggest that global warming disproportionately impacts the Arctic region, which warms significantly faster than other places. However, the consequences of uneven warming of the Earth, especially in the Arctic and sub-Arctic environment, are not well understood.

Although there are models that help analyze and predict changes in snow cover and snow melt each year, the effect of warming on frozen soil and related phenomena like frost quakes remain unclear. Experts believe there is a missing element in the methodology to predict these quakes' occurrence accurately. This could be because these rare weather phenomena are less predictable and occur at rarely instrumented locations.

In a recent study entitled "Frost quakes in wetlands in northern Finland during extreme winter weather conditions and related hazard to urban infrastructure," researchers, including those from the Geological Survey of Finland, analyzed the connection between frost quakes and thermal stress. Their finding was presented during the 2023 European Geosciences Union General Assembly.

The research team first calculated snow melt rate, snow depth, and spill temperature at various depths in the soil. Using the data they gathered, the researchers discovered that a sudden temperature decrease can lead to thermal stress, which is higher than the toughness and strength of the soil-ice mixture.

It was shown that the origin of frost quakes was related to a sudden drop in air temperature from -12 degrees Celsius to -29 degrees Celsius. As thermal stress is created, it causes huge cracks in frozen soil, houses, buildings, and roads. The study also suggests that frost quakes could be linked to climate change, making the seismic events more frequent.

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