GPS measurements of crustal deformation in Skåne, Sweden, between 1989 and 1996

Abstract

We estimate a network of crustal deformation in Skåne using observations of the Global Positioning System (GPS) from 1989, 1990, 1992, and 1996. The network straddles the Tornquist Zone, potentially one of the most active fault zones in Sweden. It includes 5 GPS sites spaced approximately 80 km apart in the south of Sweden. The precisions of the relative horizontal components for these stations are described by repeatabilities with approximately 3 mm in the north-south direction and about 1 mm in the east-west direction in 1992 and 1996, but with a precision of only about 10 mm for the horizontal components in 1989 after the improvement of broadcast orbits, keeping three fiducial station (Onsala, Wettzell, and Tromsö) fixed at the ITRF94 system. About 72% of the GPS integer carrier phase ambiguities were resolved for the 1992 and 1996 campaigns and merely 43% in the 1989 campaign. Three stations, Dalby, Limhamn, and Blentarp, moved with a rate of 4 to 5±0.5 mm/yr toward the SSE and ESE relative to the station Stavershult. SSE and ESE displacements of the three stations mean left lateral strike-slip shear along the Tornquist Zone in Skåne, which is consistent with geological results. The 2.0±0.7 mm/yr S displacement of station Kivik indicates right lateral displacement along the southern aseismic portion of the Protogine Zone. The results were similar when the Onsala station was fixed at the ITRF94. For a more detailed investigation of the present tectonic deformation in Skåne we suggest the GPS network be enlarged to more than 10 stations.