Summary
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.
