In July 2021, the seismological monitoring network of the Kola Branch of the Geophysical Survey of the Russia Academy of Sciences was expanded by installing a new seismic station. It is installed in the southern part of the Kola Peninsula in the village of Umba (station code UMBA). The expansion of the seismological network to the south has improved the monitoring detail of the Kandalaksha earthquake source zone. According to modern concepts, the Kolvitsky and Kandalaksha grabens are potentially the most seismically hazardous object in the eastern part of the Baltic Shield. To select the location of the new seismic station, reconnaissance work was carried out. This work included an assessment of the level of background seismic noise. The article presents an analysis of noise power spectral density for seismic station UMBA. A low level of background noise is shown in comparison with the NHNM and NLNM models. The following equipment is used at the seismic station: Guralp 6T analog seismometer (registration range 30 s - 50 Hz) and seismic signal recorder “Ermak-5”. Seismic data is transmitted in near real time to the Kola Regional Processing Center via mobile Internet channels. The ability to register weak seismic events with a local magnitude of less than 2 in the area of the Kandalaksha seismic zone and accurately determine the coordinates of their epicenters is shown by the example of a weak earthquake.
The article provides an overview and analysis of seismicity within the boundaries of the Arctic region for 2014, a description of seismic station networks and processing methods. The catalog of earthquakes in the Arctic region was compiled on the basis of catalogs of several organizations and seismological centers. In total, 452 earthquakes with ML≥1.5 are included in the earthquake catalog. Most of the earthquakes occurred in 2014, including all the strongest earthquakes, werelocated within the mid-ocean ridges of Mon, Knipovich and Gakkel. In the offshore territories, most of the earthquakes were confined to the Svalbard archipelago, in particular, to the seismically active zone in the Sturfjord strait. The renewal of instrumental seismological observations in 2011 (station ZFI) on Alexandra Land Island in the Franz Josef Land archipelago made it possible to record weak earthquakes in the north of the shelf of the Barents and Kara Seas. For seven earthquakes, the focal me-chanism parameters are presented according to Global CMT catalog.
In the winter months of 2018-2020 the Kola Branch of the Unified Geophysical Service RAS conducted experiments on the joint registration of avalanches in the Khibiny mountain range using seismic and infrasonic sensors during work on the forced descent of the snow mass. The aim of the experiments is to assess the possibility of avalanche detection using the geophysical methods. The lack of representative statistics on the frequency and regularity of avalanches is the reason for the relevance of developing methods of their remote registration. The difficulty of registering avalanches is due to their occurrence often in hard-to-reach areas and in poor visibility conditions. To record signals generated by avalanches, different configurations of infrasound panels consisting of three spatially separated sensors (MPA 201 or Hyperion IFS-4000 microbarographs) and a portable seismic station Guralp CMG-6TD were used. As a result of the experiments, infrasound recordings were obtained at different distances from the avalanche source. The infrasound group recordings collected from the experiments were processed using an automatic detector implementing amplitude and cross-correlation signal detection methods. The spectral composition of the recordings and their characteristic appearance were analyzed. Avalanche-induced signals are characterized by long duration and changes in azimuth to the source. The dominant frequencies of the signal lie in the region of 1-10 Hz. Conclusions are made about the insufficient sensitivity of the seismic method when the seismometer is located at a distance of the first kilometers from the avalanche source, as well as the high applicability of the infrasound method for recording the facts of avalanches. The results obtained will make it possible to develop a methodology for automatic detection of signals generated by avalanches using the data of infrasound registration. This is the necessary basis for building a system for continuous monitoring of avalanche activity.
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