Temperature measurements in subsea permafrost off the coast of Alaska
Temperature measurements have been made in shallow, small-diameter boreholes in the Beaufort, Chukchi, and Bering seas off the Alaskan coasts since 1975. Methods for making access holes with light-weight equipment are described. These included augering, water jet drilling, rotary water jet drill-ing...
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| Format: | Text |
| Language: | English |
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.575.423 http://pubs.aina.ucalgary.ca/cpc/cpc4-238.pdf |
| Summary: | Temperature measurements have been made in shallow, small-diameter boreholes in the Beaufort, Chukchi, and Bering seas off the Alaskan coasts since 1975. Methods for making access holes with light-weight equipment are described. These included augering, water jet drilling, rotary water jet drill-ing, and driving. Pipe or tubing was placed in the access holes and logged at discrete, closely-spaced depth intervals, usually one metre, t o obtain the temperature profiles. Temperature profiles in the Norton Sound area of the Bering Sea show that permafrost is absent except possibly very near shore in areas of rapid shore-line retreat. Subzero temperatures were found in all holes drilled in Kotzebue Sound, and in the Chukchi and Beaufort seas. Holes drilled in the Chukchi Sea near Barrow suggest that the shore-line is stable, or nearly so, and that ice-bearing per-mafrost is probably thin or absent a kilometre or more off-shore. In the Beaufort Sea (Elson Lagoon) near Barrow, the shore-line is retreating rapidly (i.e., a few metres per year) whereas.temperature pro-files near Prudhoe Bay suggest a retreat rate of a metre per year or less. The depth to ice-bonded per-mafrost, as determined by temperature measurements, increases with distance off-shore when the soil conditions are constant. However, ice-bonded permafrost may be found near the sea bed in areas of very fine-grained compact soils even when these occur far off-shore. The thermal data has been used |
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