Otanmäki Mine has carried out a passive seismic survey in Otanmäki in cooperation with the University of Oulu. A total of 500 geophones were installed in two NW-SE direct lines across the Otanmäki gabbro intrusion. In addition, 44 geophones were installed in a circular line around Otanmäki. The aim of passive seismic measurement is to map the dimensions and depth extension of Otanmäki gabbro intrusion and ore bearing horizon. Kari Moisio, PhD, and Nikita Afonin, a geophysicist, were responsible for the practical design and implementation of the survey on behalf of the University of Oulu. The survey started on October 28 and ended on November 26. Results of the passive seismic survey are expected to be available during the 1Q/2022.