New Rock Stress Data from Finland Related to the Update of World Stress Map

Directions and magnitudes of in situ rock stress field is crucial information for rock engineering and mine design. The Fennoscandian Rock Stress Database was initiated in 1986 to provide a collection of rock stress measurements for Finland, Norway and Sweden. Later it was expanded to include rock stress data for whole world, thus named World Stress Map (WSM). As part of more extensive update of the WSM, the rock stress data from Finland is updated after the previous update in year 1999, with results of the work presented in this paper. In the project ca. 1300 new measurement results were found and included in the database, including also some complementary data before year 1999. Most of the rock stress data is from shallow hydraulic fracturing (HF) measurements. Based on the quality classification the shallow HF measurements usually have low quality. After the last update in 1999 a new LVDT cell stress measurement method was developed providing a significant set of high quality data to the new update. The Finnish data will also be included to new Quantatitive World Stress Map database, under development.