| Autor: |
Jukka Keskinen, Pekka Heikkinen, N. Enescu, Calin Cosma |
| Rok vydání: |
2001 |
| Předmět: |
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| Zdroj: |
International Journal of Rock Mechanics and Mining Sciences. 38:843-850 |
| ISSN: |
1365-1609 |
| DOI: |
10.1016/s1365-1609(01)00049-1 |
| Popis: |
VSP surveys have been carried out at several potential nuclear waste disposal sites in Finland since the mid 1980s. To date, more than 200 three-component profiles have been measured. The main purpose of the surveys was to detect fracture zones in the crystalline bedrock and to determine their positions. Most seismic events could be linked to zones of increased fracturing observed in the borehole logs. The more pronounced seismic reflectors could be correlated with hydro-geologically significant zones, which have been the main targets in the investigations. Processing and interpretation methods have been developed specifically for VSP surveys in crystalline rocks: • Weak reflections from thin fracture zones are enhanced by multi-channel filtering techniques based on the Radon transform. • The position and orientation of the fracture zones are determined by polarisation analysis and by combining data from several shot points. • The compilation of the results from several boreholes gives a comprehensive image of the fracture zones at the scale of the whole site. The discussion of the methodology is based on examples from the Olkiluoto site, in SW Finland. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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Full Text from ScienceDirect