The seismic experiment SVEKA’81 (also referred to as SVEKA) is the first high quality deep seismic sounding survey conducted in Finland (Luosto et al. 1984). The 325 km long SVEKA’81 profile runs from the Central Finland granitoid complex of the Svecofennian domain through the Ladoga-Bothnian Bay zone to the Archean Karelian province. The field measurements were made in June 1981 by recording 45 explosions at five shot points in shallow lakes using 19 seismic stations occupying different positions in multiple deployments. 4 five-channel and 15 three channel instruments, including both analog and digital recorders, were used at 2 km average station spacing along the profile. A two-dimensional crustal P-wave velocity model for the SVEKA’81 profile was constructed from the wide-angle data by Luosto et al. (1984). The model shows Moho depths of around 55-60 km with the thickest crust in the middle of the profile and varying velocity structure in the upper crust. A wide-angle vertical component section of the SVEKA’81 profile is also available. A continuation of the SVEKA profile to the southwest called SVEKA’91 was surveyed in 1991. A simultaneous interpretation and modelling of these profiles has been carried out by Janik et al. (2007). Janik, T., E. Kozlovskaya, and J. Yliniemi, 2007. Crust-mantle boundary in the central Fennoscandian shield: Constraints from wide-angle P and S wave velocity models and new results of reflection profiling in Finland. Journal of Geophysical Research: Solid Earth 112. Luosto, U., E. Lanne, H. Korhonen, A. Guterch, M. Grad, and R. Materzok, 1984. Deep structure of the Earth’s crust on the SVEKA profile in central Finland. Annales geophysicae 2: 559–570.

2022