Extending the seismic monitoring network in Hornsund

Five new seismic sensors installed at Hornsund

The access project, which was led by Mariusz Majdański (Institute of Geophysics, Polish Academy of Sciences), aimed to install five new seismic sensors close to Hornsund, to work in combination with the existing seismic station at the Polish Polar Station Hornsund. A seismic array, which is a setup of closely-spaced sensors, allows detection, classification, and location of weak seismic signals, and is therefore superior in its monitoring performance compared to a single seismic station. A long-term deployment of a seismic array at Hornsund is thus expected to significantly increase the overall event detection and location capability for the region, as well as for the sedimentary basin of the Barents Sea, where large hydrocarbon deposits have been found. Furthermore, an array offers the possibility to monitor ocean-generated microseisms, the long-term trends of which can be indicative of change in oceanic and atmospheric processes. This array was built as a joint international activity by EPOS-Norway, SIOS, IG PAS and NORSAR.

The initial plan for the project was for three expeditions to Hornsund in 2020. Because of COVID-19 pandemic limitations, the project was realised in 2022.

The first expedition, in autumn 2021, was to select optimal locations for installation to assure the highest possible data quality. To reduce ambient noise, and thereby to increase the array sensitivity, the seismic sensors were installed in shallow (2 metre) boreholes in nearby rocky outcrops. These boreholes were drilled in early May 2022, when the ground was snow-covered and frozen (Figure 1). 

Figure 1. Drilling rig in operation on snow-covered ground, with nearby power generator and snow scooter. Photo credit: Krzysztof Otto.

The final expedition in July 2022 prepared electric cables (power and communication), deployed seismic stations (Figure 2) and connected the whole system with the Hornsund station network. Currently the data are gathered and are transferred to NORSAR. After a quality control and initial processing, the data will be openly available through the Norwegian node of the ORFEUS EIDA system (Datacentres of the European Integrated Data Archive). There will be unrestricted data access to all raw seismic records and all metadata will be included in the SIOS database.

The contribution of the project to SIOS is the expansion of the existing seismic measurement network in Svalbard, providing data for different disciplines such as glaciological, permafrost, climate, and tectonic research. It brings a new monitoring technique in the form of a seismic array to Hornsund where previously only a point observation was performed. The array techniques will significantly improve detectability and location for seismic signals in the relatively active southern Spitsbergen region. The effort strengthens international cooperation between Polish and Norwegian institutions and scientists. 

Figure 2. The final secured seismic station in a hard rock outcrop. Photo credit: Krzysztof Otto.