New data about seismicity and crustal velocity structure of the “continent-ocean” transition zone of the Barents-Kara region in the Arctic

Abstract

The recent (2011) installation of seismic station Zemlya Franca-Iocifa (ZFI) on Alexander Island in the Franz Josef Land Archipelago allows new seismic monitoring of the “continent-ocean” transition zone of the Barents-Kara Sea region. The region is seismically active, and we hypothesize that the prevailing geodynamic factor responsible for the occurrence of weak earthquakes is isostatic compensation of avalanche sedimentation in the “continent-ocean” transition zone. The crustal velocity structure beneath ZFI was determined using receiver functions. Crustal thickness is 30 km, based on an observed Moho discontinuity with underlying mantle velocities being Vp = 8.15 km/s and Vs = 4.5 km/s The model indicates a mid-crustal boundary at a depth of about 17 km with a velocity contrast between the upper (Vp = 6.1 km/s, Vs = 3.6 km/s) and lower (Vp = 6.8 km/s, Vs = 3.9 km/s) layers. In addition, the upper crustal sedimentary layer is about 4 km thick with Vp = 4.3 km/s and Vs = 2.36 km/s.