SVEKA'91 wide-angle refraction and reflection profile

The deep seismic sounding profile SVEKA’91 is the continuation of the original SVEKA’81 profile (Luosto et al. 1994). SVEKA’91 wide-angle seismic measurements took place in August 1991 southwest of the original SVEKA’81 profile. The 350 km long profile begins near Uusikaupunki at the southwestern coast of Finland and ends in Kannonkoski, Central Finland, partly ovelapping with the SVEKA’81 profile. The objective of the SVEKA’91 project was to investigate and map the crustal structure in the area between the pre-existing BABEL and SVEKA’81 profiles. The SVEKA’91 profile runs through the Southwest Finland rapakivi intrusion, Satakunta sandstones, Tampere schist belt and the Central Finland granitoid complex. Large explosions (200-1440 kg) at five shot points and small explosions (80 kg) at two shot points were used as seismic sources along the profile. The explosions were recorded by 29 digital and 6 analog stations spaced on average 2 km apart. A two-dimensional crustal P-wave velocity model was obtained from the recordings of SVEKA’91 by Luosto et al. (1994). The velocity model shows smooth crustal thickening to the northeast from 48 to 56 km Moho depth. A wide-angle vertical component section is available for SVEKA’91. Also separately available are new P- and S-wave models of both SVEKA’81 and SVEKA’91 published 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., M. Grad, A. Guterch, P. Heikkinen, T. Janik, K. Komminaho, C. Lund, H. Thybo, and J. Yliniemi, 1994. Crustal structure along the SVEKA’91 profile in Finland. European Seismological Commission, XXIV General Assembly 19–24.