Talvikangas in Finland was hit by 26 鈥渇rost quakes鈥� in just 7 hours in January, a new analysis has found, in what is thought to be the highest concentration of the phenomenon ever recorded.
The flurry of frost quakes 鈥� also known as ice quakes or cryoseisms 鈥� happened between 4am and 11am on 6 January, startling local residents with a series of loud cracking sounds coming from the ground.
The seismic activity was recorded by researchers at the Geological Survey of Finland, who are monitoring frost quakes in the area and have now analysed the data.
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Frost quakes occur when a rise in temperature causes snow to melt, saturating soils with meltwater. When temperatures dip rapidly, the water in the ground refreezes and expands, causing ruptures.
The high number of quakes in such a short space of time in Talvikangas lends weight to fears that frost quakes are becoming more frequent in Arctic and sub-Arctic regions, .
Talvikangas, a suburb of the city of Oulu, is no stranger to frost quakes. Since 2014, cracks have started appearing in roads and houses in the neighbourhood. In 2016, residents reported hearing a loud noise and feeling the ground shake before seeing cracks appear. Similar incidents were reported in 2019 and 2020.
But the 2023 frost quakes are the first that researchers have managed to capture seismic data for. 鈥淯sually, it just happens, and people think 鈥榳hat was that?鈥�,鈥� says at the Geological Survey of Finland. He presented the findings at the
Frost quakes occur across the Arctic and sub-Arctic regions, but go mostly unreported. Researchers have little idea how common they are or whether they are now happening more often.
But changing weather patterns may well be influencing frost quake frequency. Arctic regions , bringing them well above freezing during winter periods for short spells.
In Finland, there is usually permanent snow cover in winter, says Okkonen. 鈥淏ut if temperatures fluctuate above and below zero, it initiates the snow melt and it saturates the soil with water. After that, if we have a huge drop in the temperature鈥� it can initiate these frost quakes.鈥�
If climate change is driving more frost quakes, it could have implications for Arctic and sub-Arctic communities, says Okkonen. In particular, it could hit airports and roads, where cracks can be time-consuming and costly to repair.
Some areas are likely to be more susceptible to quakes, depending on the local climate and soil conditions. Okkonen and his colleagues are building a hydrological model covering the global Arctic and sub-Arctic to pinpoint vulnerable areas and map their findings against climate models, in order to establish whether rising temperatures are increasing the risk of more frequent and severe frost quakes.
