Subsea Permafrost in Harrison Bay, Alaska: An Interpretation from Seismic Data

Velocity data derived from petroleum industry seismic records from Harrison Bay show that high-velocity material ( or = 2 km/s) interpreted to be ice-bonded permafrost is common. In the eastern part of the bay, the depth to high velocity material increases and velocity decreases in an orderly manner...

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Bibliographic Details
Main Authors: Neave,K Gerard, Sellmann,Paul V
Other Authors: COLD REGIONS RESEARCH AND ENGINEERING LAB HANOVER NH
Format: Text
Language:English
Published: 1982
Subjects:
Physical and Dynamic Oceanography
Seismology
Snow
Ice and Permafrost
*SEISMIC WAVES
*PERMAFROST
VELOCITY
ANOMALIES
SEISMIC DATA
ATTENUATION
REFRACTION
SUBSURFACE
OCEAN BOTTOM
GEOPHYSICAL PROSPECTING
BEAUFORT SEA
PETROLEUM GEOLOGY
Harrison Bay(Alaska)
Beaufort Sea
Ice
permafrost
Alaska
Online Access:http://www.dtic.mil/docs/citations/ADA121020
http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA121020
Description
Summary:Velocity data derived from petroleum industry seismic records from Harrison Bay show that high-velocity material ( or = 2 km/s) interpreted to be ice-bonded permafrost is common. In the eastern part of the bay, the depth to high velocity material increases and velocity decreases in an orderly manner with increasing distance from shore until the layer is no longer apparent. The western part of the bay is less orderly, possibly reflecting a different geological and thermal history. This western part may be an inundated section of the low coastal plain characterized by the region north of Teshekpuk Lake, and could have contained deep thaw lakes, creating low velocity zones. Along some seismic lines, the high-velocity material extends approximately 25 km offshore. Two anomalies have been found which could be associated with rapidly degrading permafrost. One is strong attenuation, which was interpreted as an indication of gas in the shallow deposits. The other is the presence of considerable seismic noise, including identifiable small seismic events. The origin of this noise has not been positively established, and it is proposed that it may indicate that some movement is occurring in the sediments due to thaw.

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