THE DEVELOPING OF GROUND RESPONSE SPECTRA FOR EXTREME SEISMIC EVENTS IN SOUTHERN FINLAND

摘要

The purpose of the current paper is to present the task, the methods and the results for the ground response spectra for nuclear construction sites in southern Finland. The results of this study will form a key design in formation for the design of the plant structures, piping and equipment. The first task of the study was the development of attenuation relationships for southern Finland. For this task the approach of tektonically and geologically similar regions was adopted. For these regions the Saguenay region and the southwestern Australia were chosen. The second task in the study was the division of the southern Finland to six source areas and the determination of magnitude recurrence relationships for these source areas. The identified sources for the study were: 1) Swedish coast, 2) Aland archipelago-Estonian coast strip, 3) Bothnian gulf-lake Ladoga strip, 4) the bottom of Bothnian gulf- White sea strip, 5) Riga bay - Latvia area, 6) background seismicity. The third task of the study was the seismic hazard determination of the investigated area it was done for the different frequencies. The frequency band investigated covered frequencies from 0.5Hz up to 50Hz and the number frequency points were about 10. The conclusion of the study is that ground response in southern Finlands low seismicity precambrian rocks is from 0.1- 0.15g for zero period acceleration and that the spectral shapes of the obtained spectra are quite flat, amplification factors being less than three and the spectral peaks are located at frequencies higher than 10Hz.