Exploring seismicity and ice cover of Livingston Island - research projects

Livingston Island is one of the eleven islands of the South Shetland Archipelago which is separated from the Antarctic Peninsula by Bransfield Strait and from South America by the Drake Passage. The South Shetland Islands, where the Bulgarian Antarctic Base is located, is characterized by complex geodynamics, including: subduction zones, zones of splitting of the old crust and arising of a new crust, numerous volcanoes. The most of the territory of the Island is coated by permanent snow cover and glaciers. In recent decades, a number of scientific institutions have been working on projects related to the study of various aspects of the seismic regime and the structure of the Еarth's crust in the region of the South Shetland Islands and Antarctica in general, as well as the state and dynamics of the ice sheet. However, this region of the Earth remains still unexplored. Harsh climatic conditions are a serious obstacle for conducting long-term research. Bulgarian scientists from Sofia University "Sv. Kliment Ohridski" and the National Institute of Geophysics, Geodesy and Geography of the Bulgarian Academy of Sciences have been studying the seismicity of the Livingston Island region and the behavior of the glaciers near the Bulgarian Antarctic Base within the framework of three scientific projects since 2014. The projects are funded by the Bulgarian Scientific Fund and National Center for Polar Studies.

One of the aim of the projects is to study the activity of the glaciers during different seasons by combining seismic and GNSS measurements. Seismic registration was carried out by the seismic station LIVV installed previously as temporary station and later developed as a year-round one. GNSS measurements were carried out at certain points on the surface of the glacier Balkan. The resulting estimates of the speed of glacier movement at these points were interpreted in conjunction with the seismic data, thus making an initial attempt to determine the nature of the recorded icequakes. The relationship between seismic activity in the glacier and the change in the temperature of the environment during the astral summer and the astral winter was studied.

The study of the seismicity and ground structure of Livingston Island and the surrounding area have been carried out using the data recorded by the Broadband seismic equipment of the LIVV station, applying a software code developed for this purpose.

Investigating seasonal variations in seismic noise is another goal of the projects. The recorded seismic noise provided information on the condition and behavior of the seismic equipment throughout the recording period, as well as on the sources of seismic noise and their influence on the recording capabilities of the station.