Seismological investigations in the Livingston Island (Antarctica) using the LIVV station’s records

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Antarctica has been considered as an aseismic continent few decades ago. Nowadays with presence of hundreds modern seismometers the scientists reveals that a lot of earthquakes with small to moderate magnitudes happens every day with tectonic, volcanic or glacier origins. The seismicity of Livingston Island, where the Bulgarian Antarctic base is situated, is moderate with respect to other parts of the Antarctica, but in its vicinity there are active volcanoes, active subduction zone, active rifting zone and extinct or active spreading ridges. The movements and fracturing of the glaciers on the Livingston also create a lot of micro and small seismic events. The first Bulgarian Antarctic broadband seismic station, with international code name LIVV, is working every Antarctic summer since the season of 2015/2016. Installation and operation of the station is done in the frame of the project DFNI I02/11 funded by the Bulgarian Ministry of Education and Science. A software code was developed to calculate location of events using the method of Golitzyn. The method uses a tree component station record to localize an event. The precision of the method is not good for distances more than 30 km but the results indicate eventual seismically active zones. Such active zone is detected in the east part of the Island. Also a study of the noise distribution was performed and initial evaluation of the magnitude of the registered local events was performed. The signals from a number of strong to moderate regional and teleseismic events were analyzed by frequency-time analysis, applying floating filtering. Obtained dispersion curves were inverted by optimized non-linear inversion software procedure ONLI in order to obtain the velocity structure of the Earth between the source and the receiver. Results evidenced relatively thick crust for the traces crossing the continent and a very thin crust with well-pronounced low-velocity asthenosphere channel for the traces, crossing oceanic areas.