HSPB seismic broadband station in Southern Spitsbergen: First results on crustal and mantle structure from receiver functions and SKS splitting

Wilde-Piorko M, Grad M, Wiejacz P, et al.

Polish Polar Research

30(4), 2009, 301-316

In the framework of the 4th International Polar Year Panel Plate Tectonics and Polar Gateways the international project The Dynamic Continental Margin Between the Mid-Atlantic-Ridge System (Mohns Ridge, Knipovich Ridge) and the Bear Island Region was undertaken in 2007-2008. As a part of this project a new three-component seismic broad-band station was installed in September 2007 in the area of the Polish Polar Station Hornsund in Southern Spitsbergen. The new HSPB station has the coordinates: φ = 77.0019°N, λ = 15.5332°E, H = 11 m a.s.l. During the first years of operation a number of good quality teleseismic events were recorded. This gives the opportunity for a first determination of crustal and mantle structure beneath the station by using receiver function (RF) and SKS splitting techniques. The Moho depth determined using RF is about 32 km beneath HSPB. Significant amplitudes on the transverse components of the RF indicate a shallowly dipping discontinuity (sedimentary-basement) towards the south-west. The fast polarization of SKS phases is near parallel to the border between the continental and the oceanic crust and the Hornsund fault (α = 151.8). The average time delay δt between "fast" and "slow" directions is 0.68 s, which implies ca. 2% anisotropy in a 100-200 km thick layer in the mantle.