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Using a laser and monitoring the propagation of seismic waves.
Researchers from the Institute of Dynamics of the Geospheres of the Russian Academy of Sciences have developed and tested a system for monitoring the parameters of the fields being developed, next to which there is a threat of sudden subsidence of rocks causing artificial earthquakes. As a result of the experiments, scientists came to a conclusion about the suitability of their methods for predicting artificial seismic phenomena. The corresponding article was published in Journal of Mining Science.
Currently, the extraction of ores, as well as gas and oil, often necessitates the excavation of large volumes of rock. If such a seizure occurs alongside faults and geological faults, subsidence in such areas can lead to marked artificial earthquakes even where natural earthquakes do not normally occur. This phenomenon is especially frequent in areas of horizontal drilling – for example, in the production of shale oil and gas. Recently, the development of the Bazhenov suite has begun in Russia in this way, so it is very likely that the problem of artificial earthquakes will become even more urgent in our country.
The authors of the new work created a model that allows predicting the probability of earthquakes depending on how seismic waves propagate through fault lines in certain deposits. To test its work in practice, geophysicists conducted monitoring of the Korobkovo area (Belgorod region), where iron ore is mined (part of the Kursk magnetic anomaly).
To determine the speed of seismic waves propagation across the boundaries of the field, scientists organized weak artificial explosions in the underground part of the mine and then measured their intensity using three-component accelerometers A1638 (manufactured by Geoacoustics, Russia) sensitive to waves of 0.2-400.0 hertz, geophones GS-20DX (Geospace International, Russia) with a working range of 10-400 hertz. And for highly accurate measurements of rock movements at the boundaries of the deposit, the laser ILD2300-100 (Micro-Epsilon, Germany) was used with an accuracy of measurements up to one micrometer.
Measurements showed that at the boundaries of the ore veins Main and Sretenskaya energy dissipation is rather weak, that is, there is a fault where artificial seismic events of appreciable strength are possible. More importantly, it was thus possible to confirm that the new system allows pointing to the places where artificial earthquakes are most probable and taking appropriate measures in advance. The relevance of this technology as new methods of mining grows can significantly increase.