Automatic detection of circular depressions in digital elevation data in the search for potential Norwegian impact structures

摘要

Presently, 174 impact craters are proven on Earth, and of these 10 are located in Finland, 6 in Sweden and only 2 in Norway (Gardnos and Mjalnir). A pattern matching algorithm (correlation) based on 100 m digital elevation data was used in a regional study to discover circular depressions in the search for possible new Norwegian impact structures. By applying this technique to detect depressions of 5 - 10 km diameter in Finnmark, northern Norway, about 23 large circular structures were found in a 14,000 km2 area of Precambrian rocks. Circular features are clearly displayed in the detected structures. The large number of candidates in this area, however, makes field inspection inconvenient and time consuming, and supplementary screening methods should be considered to help reduce the number.