Monitoring long-term changes of glacial seismic activity with continuous seismological observations: a case study from Spitsbergen

Abstract. Changes in the global temperature balance have proved to have a major impact on the cryosphere and therefore retreating glaciers are the symbol of the warming climate. Long-term measurements of geophysical parameters provide the insight into the dynamics of those processes over many years. Here we explore the possibility of using data recorded by permanent seismological stations to monitor glacial seismic activity. Our study focuses on year-to-year changes in seismicity of the Hansbreen glacier (southern Spitsbergen). We have processed 7-year-long continuous seismological data recorded by a broadband station located in the fjord of Hornsund, obtaining seismicity distribution between 2008 and 2014. To distinguish between glacier- and non-glacier-origin events with the data from only one seismic station in the area, we developed a new fuzzy logic algorithm based on the seismic signal frequency and the energy flow analysis. Our research has revealed that the number of detected glacier-origin events over the last two years has doubled. We also observed that the annual events distribution correlates well with the temperature and precipitation data. In order to further support our observations, we have analysed 5-year-long seismological data recorded by a broadband station located in Ny-Ålesund (western Spitsbergen). Distribution of glacier-origin tremors detected in the vicinity of the Kronebreen glacier shows a steady increase from year to year, however not as significant as for the Hornsund dataset.