Geophysics and Subsea Permafrost 249
Marine permafrost studies have been conducted near shore in Prudhoe Bay, Alaska. Sound veloc-ities, measured in the ocean sediments were used to determine the location of frozen materials. Veloc-ities above 2500 m/s were judged to indicate frozen materials while lesser velocities were associated wit...
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| Format: | Text |
| Language: | English |
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.559.763 http://pubs.aina.ucalgary.ca/cpc/cpc4-249.pdf |
| Summary: | Marine permafrost studies have been conducted near shore in Prudhoe Bay, Alaska. Sound veloc-ities, measured in the ocean sediments were used to determine the location of frozen materials. Veloc-ities above 2500 m/s were judged to indicate frozen materials while lesser velocities were associated with non-frozen materials. A study area 1 km by 0.5 km was established, in waters ranging from 0.4 to 3 m deep near shore. Over 100 velocity measurements were made in the area. These measurements show a broad variation in frozen material velocities and a definite trend toward lower velocities with increasing distance from shore. Velocities near 4000 m/s were typically found within a few hundred metres from shore while at 1 km from shore the frozen material velocities were approximately 3000 m/s. No significant variation in frozen material velocities was observed in the direction parallel to the shore-line. The depth to the top of the frozen materials was found to vary widely over the study area suggesting a highly irregular and discontinuous material with little or no continuity to its upper surface. Typical depths to high velocity refractors ranged from about 5 m within 100 m of shore to about 25 m at 1 km from shore. On a effectuk des etudes du pergelisol sous-marin prtts du rivage, dans la baie de Pmdhoe en Alaska. On a employe la vitesse de propagation du son, mesuree dans les sediments sous-marins, pour deter- |
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