Such conclusion was made by scientists of the Otto Schmidt RAS Institute of Physics of the Earth and k-J the Institute of Ecological Problems of the North of the RAS Ural Branch Arkhangelsk Scientific Center after a series of joint research works in high latitudes.

Everyone knows that wind shakes multistory buildings, cranes, factory chimneys, and other skyscraper constructions. Waves of their mechanic vibrations are transmitted through bearings and the substructure into the ground and are spreading over long distances. But why are they so interesting? Only sensitive seismic instruments can register these vibrations.

However, it was found out: such vibrations can be used for "X-raying" geological environment for studying its structure. Near Archangelsk, specialists took advantage of this opportunity and began to measure how this seismicity develops in time and space at a different distance from the object radiating its own vibrations of concrete constant frequency under the impact of wind. Observations showed that the amplitude of monochromatic signal is characterized by areal changes. Its attenuation zone was extended to the northwestern direction, i.e. coincided with a proposed geological fracture.

Since construction of a new atomic power plant was planned in this area, the scientists decided to carry out its preliminary studies. As a result, they revealed a shadow zone, i.e. signal attenuation zone. Concurrently it was found out that it radiates less vibrations than constant microseismic vacillations of our planet. Further research showed that nanoearthquakes are governed by the same physical laws as severe devastating earthquakes. By the way, theoretical studies proposed this even earlier, but there was no practical confirmation of this hypothesis-it has originated only recently.

Thus, studies of microvibrations helped specialists to enrich their knowledge of behavior of "real" seismic blows; but studies of natural seismic events are very expensive and require a network of appropriate stations, sophisticated equipment, and continuous observations*. It is also necessary to use considerable efforts to understand the structure of the Earth's crast. For this purpose scientists have to artificially cause vibrations by means of light subsurface explosions**, to drill wells or use sources of vibrations, which are usually applied in the course of seismic zoning. Such works require a lot of money, damage the environment, and are hazardous. While the wind blows by itself and absolutely "free of charge".

At the beginning of research works scientists began to register microshocks. They believe that these shocks are caused by shifts of rock blocks of some hundred meters up to 3 km, whereas powerful earthquakes are produced by rock blocks of dozens of kilometers. As a result the scientists elaborated the method of determining coherence*** coefficient that allowed to single out microsignals from a multitude of signals. The chart represents both these signals and macroearthquakes in the form of a straight line. This regularity was determined in the mid-1940s by scientists B. Gutenberg (Germany) and С Richter (USA).

Having in arsenal the effective method and necessary equipment, the scientists gained an opportunity to carry out seismic microzoning, estimate structural integrity of buildings without causing any harm to constructions. These works are of particular importance for designing strategic objects-nuclear power stations, chemical plants, burial grounds for environment-unfriendly wastes, gas pipelines.

Even first results of research work carried out in Arkhangelsk revealed alarming information. It turned out that some buildings that seemed to be secure and monolithic consist of separate blocks structurally disconnected. It is likely the result of work of time, ground waters, humid climate; may be the integrity of buildings was damaged by incompetent restorers. As a result, any shake could cause domestic gas explosion, light earthquake or other catastrophe.

But today the scientists have developed rather cheap and reliable method of obtaining data on the strength of our houses, i.e. they know what lies under the substructure.

Plotnikova Т., "Earthquake Caused by Wind", Nauka Urala newspaper, No. 26 - 27, 2005

Prepared by Yaroslav SIBIRTSEV

* See: V. Morgunov, "Earthquake Forecasts for Tomorrow", Science in Russia, No. 1, 2004. - Ed.

** See: B. Golubev, "This Troubled Planet of Ours", Science in Russia, No. 4, 2005. -Ed.

*** Coherence-coordinated course of several oscillatory or wave processes in time with a constant difference in phases; in case of summation coherent waves either amplify or attenuate each other. - Ed.

Постоянный адрес данной публикации: