In our study, we show the results of a passive seismic interferometry application for mapping the uppermost crust in the area of active mineral exploration in northern Finland. The obtained velocity models agree well with geological data and complement the results of reflection seismic data interpretation.

The paper describes the history and the present state of instrumental seismic observations at the University of Oulu and Sodankylä Geophysical Observatory in northern Finland that started in 1950s. This includes both seismic observations at permanent seismic stations and temporary seismic experiments by portable seismic equipment. We describe the instrumentation and major research topics of seismic group at the SGO and discuss the plans for their future development.

We address the problem of seismicity in the intraplate area of northern Fennoscandia using the information on local events recorded by the POLENET/LAPNET seismic array. We relocate the seismic events, calculate a 3-D tomographic P wave velocity model of the uppermost crust and investigate a focal mechanism of the event. Our results demonstrate that the Baltic-Bothnia Megashear is an important large-scale, reactivated tectonic structure that has to be taken into account when estimating seismic hazard.