Regional landslide occurrences and possible post-glacial earthquake avtivity in northwest Western Norway: Phase A2; Penetration echo- sounding in 5 lakes in Sunnfjord and Nordfjord
Fives lakes in Ørsta, Volda and Nordfjordeid communes are mapped using a Knudsen 320 M/P 12 Khz echo-sounder. From the echo-sounding profiles there are made maps for the lakes. The acoustic profiles are interpreted at NGU with regard to disturbances of the lake-sediments - like slides or tectonic shaking. Slides are registered in all lakes. In four of the lakes these slides may have been generated from steep slopes surrounding the lakes, while in the fifth - Storesetervatnet in Nord- fjordeid - the disturbances seen, have happened entirely within the lake sediments themselves. Based on the interpretation, we suggest a coring program covering all five lakes to verify the genesis of these disturbances and to date them. Adjustment to the program must be expected during coring when seismic data and cores can be related.