MOSCOW, January 10, Tatyana Pichugina The northern countries are threatened by a dangerous natural phenomenon, scientists warn. In northern Europe, the USA and Canada, at the beginning of winter, strange tremors occur, houses tremble, roads are destroyed. But seismographs do not detect deep sources. looks into what is known about frost shaking.
«The whole house was shaking»
In the early morning of January 2, 1999, loud bangs and tremors woke up the residents of Randolph in the US state of Massachusetts . The police received dozens of alarm calls, people ran out into the street in the cold.
“The whole house was shaking, pictures were falling from the walls, glasses in the cupboard, window panes were clinking, car sirens were howling,” local newspapers wrote. People wondered what it was: an earthquake or an explosion.
In science, this is called frost shaking. They occur in northern regions during a sharp drop in air temperature and have never attracted much attention before.
Frostquakes were reported as early as the 19th century, although at that time they were confused with tectonic earthquakes. The history of this phenomenon was studied most fully by Andrei Nikonov from the Schmidt Institute of Earth Physics of the Russian Academy of Sciences.
It was well known to residents of the north of the European Plain and Siberia. This is evidenced by newspaper articles, scientific reports and seismic data. Overlaying the number of events on the time scale shows a noticeable tendency for tremors to occur during the winter months, especially January.
In 1912- The German scientist Gutenberg suggested that this was due to the freezing of the soil. But attention was paid to his work only in the second half of the 20th century.
Having summarized historical and modern data, Nikonov made the following conclusions. Frost shaking occurs only in winter (during particularly severe frosts) at night or early in the morning. Their likelihood is higher if there are lowlands, reservoirs, moist soil nearby, or the ground is free of snow. A prerequisite is a sharp drop in air temperature by 10-20 degrees.
The tremors are felt for hundreds of meters around, a maximum of several kilometers. Accompanied by crackling, noise, underground rumble. Faults and cracks often form.
In past eras, colder than the current one, frost shocks were more frequent, says American geologist Patrick Baros. They participated in the formation of polygonal structures of the late Pleistocene. The material that fills ancient cracks is similar to what is found in modern ones.
Frostquakes are close to ice impacts known to Antarctic researchers. This phenomenon is also being studied in the ice of Lake Baikal.
< br />
Where it freezes, it breaks
Frost shaking occurred in recent years in Finland, the USA (in Chicago), Canada (in Ottawa and the province of Alberta) . Thus, residents of the Finnish Oulu reported a series of tremors on January 6, 2016. They heard loud bangs, felt vibrations in the ground, and then saw cracks in the ground.
A seismic station 14 kilometers away recorded a series of unusual local tremors, accompanied by Rayleigh waves of large amplitude. This indicated that their source was close to the surface.
It became very cold that day. So the shaking was caused by special weather conditions.
Usually frost shocks are no stronger than five, this is not very dangerous. But they can cause damage.
Roads and other surfaces free of snow are especially vulnerable. In a recent study, scientists from the University of Oulu identified another source of frostquakes — swamps, places where water accumulates during rainy autumn or early winter, during a thaw. As soon as frost hits, when the temperature drops to minus 20 degrees in a matter of hours, the water seizes and tension arises in the soil. Cracks form and tremors occur, comparable to earthquakes and mountain explosions.
To do this, the soil must freeze at least five centimeters. Cracks can be very deep and can damage buildings, foundations, gas pipelines, and roads.
“Against the backdrop of climate change, unusual weather events have attracted the attention of the general public. Frost shocks occur more often than we think,” says one of the authors of the work, Kari Moizio. Tremors of this type are ubiquitous in the northern regions, but they have been little studied by seismic methods, he adds.
Scientists installed two seismic stations near Oulu and recorded all the tremors that occurred in the winter of 2022-2023, as well as the soil temperature. For several days, when the air temperature dropped rapidly — by a degree per hour, local residents reported underground tremors and unusual sounds. This helped highlight the signals of frostquakes. Their source was located nearby, in the swamps.
Frostquakes can probably be predicted based on weather conditions. Also, more detailed studies will help assess areas at risk and prevent infrastructure destruction. Scientists intend to create a warning system based on soil analysis and satellite data.
Requires monitoring
“Cryoseism, or frostquake, is an unusual and rather rare seismic phenomenon, which is also very difficult to record and confirm. Seismic activity manifests itself in cases when, due to severe frosts, not only the ground freezes, but also groundwater, which, freezing, they begin to expand, creating pressure on the soil,” comments Vadim Petrov, Chairman of the Public Council at Roshydromet, State Secretary of the Ecological Chamber of Russia.
«A frostquake is a seismic event caused by the sudden cracking or stress of frozen soil or rocks saturated with water or ice. They are sometimes mistaken for ordinary earthquakes, but there are differences. Frostquakes have a small magnitude and may not be recorded by seismographs. In addition, the events are strongly are localized and in some cases do not extend more than a few hundred meters from the source,” adds Mikhail Volkov, teacher of the highest qualification category, geography methodologist at the Internet Lesson Home School.
According to Petrov, for cryoseismic activity to occur, at least three conditions must coincide : rain soaks the ground, the soil is devoid of snow cover, the temperature drops sharply.
“We need low temperatures,” Volkov clarifies. That is why this phenomenon is typical for the USA, Canada, Finland, Iceland, and Denmark. In Russia, frostquakes occur in the northern and northeastern regions, as well as in Yakutia, the Irkutsk region, and the Krasnoyarsk Territory.
In the scientific literature, Petrov says, there are sometimes suggestions about a connection between global climate change and the frequency of cryoseisms.
«Scientists see the reason in sharper changes in air temperature,» explains Volkov.
According to official reports, no such phenomena were recorded on the territory of Russia, notes Vadim Petrov.
«To monitor They launched a state system of background monitoring of permafrost, consisting of 140 reference points for continuous monitoring of soil temperature,” the expert reports.
According to him, the first point of the monitoring system was opened in May of this year in Salekhard. A comprehensive permafrost monitoring network will be deployed by the end of 2025 throughout the permafrost zone, which covers most of the Russian Federation.
Свежие комментарии