Nanoearthquakes at the service of science
Geologists at the Institute of Ecological Problems of the North SB RAS and the Schmidt Institute of Physics of the Earth have found a means to reveal mild fractures of the Earth’s crust on platform territories, using small earthquakes, the energy of which is far lower than standard, recordable earthquakes.
This research is important for an understanding of global processes in the Earth’s solid shell, the role played in them by relatively calm fields, and also to resolve tasks related to the positioning of strategically important sites, such as atomic power stations, pipelines, radioactive waste storage sites and so on.
Seismic phenomena on terrestrial platforms are very weak: in energy terms they are about nine orders lower than regular ones and, therefore, they are called nanoearthquakes. Their discovery and analysis requires delicate experiments, conducted by the researchers in the region of the estuary of the River Severnaya Dvina, not far from Archangelsk. Experiments were conducted using two simultaneously operating portable digital seismometric stations, moving over the platform. Seismic radiation parameters were defined for each site, comparable with the technogenic seismic signal that transmits through the medium. In this way the scientists found places of anomalous absorption of the probing signals – supposed ruptures of the Earth’s crust – and they inserted them into a map of the territory. In this work nanoearthquakes were observed for the first time; phenomena that were previously only predicted in theoretical terms.