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Abstract:
Accurate seismotectonic studies on and around Spitsbergen, European Arctic, are impeded by a number of difficulties. The largely glaciated environment and the geographic distribution of land and sea restrict geotectonic mapping, as well as the deployment of dense, local seismic networks. The nature of tectonic seismicity in the region, which is episodic and dominated by moderate to low event magnitudes, imposes additionally its own challenges. So far, the best studied activity has been the Storfjorden 2008-2016 earthquake series (Mw 6.1, 21 February 2008; Mw 5.1, 29 March 2016) and background seismicity in the offshore area east of southern Spitsbergen, and to a lesser extent, seismicity in Heerland, on central Spitsbergen (mb 5.5, 18 January 1976). Despite the aforementioned challenges, the improvement of the regional seismic network from 2010 onward, has been offering enhanced insight into Svalbard seismotectonics, in particular in areas best covered by seismic station distribution. One such case, is the Hornsund area, where the calculation of moment tensor solutions was possible for two moderate magnitude, onshore events (Mw 4.3, 4 July 2015; Mw 4.6, 31 May 2017). The nearby broadband station facilitates event focal depth determination, insights into the local tectonic structure enabled by geological mapping. We will present the focal characteristics of the activity associated with these earthquakes and discuss their placement within the local and regional geotectonic setting.
