SEISMIC AND ELECTRICAL PROPERTIES OF UNCONSOLIDATED PERMAFROST 1

• Published in: Geophysical Prospecting
• Main Authors: KING, M. S., ZIMMERMAN, R. W., CORWIN, R. F.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 1988
• Subjects: Ice; permafrost
• Online Access: http://dx.doi.org/10.1111/j.1365-2478.1988.tb02168.x; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1365-2478.1988.tb02168.x; https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1365-2478.1988.tb02168.x

ABSTRACT A model has been developed to relate the velocities of acoustic waves V p and V s in unconsolidated permafrost to the porosity and extent of freezing of the interstitial water. The permafrost is idealized as an assemblage of spherical quartz grains embedded in a matrix composed of spherical inclusions of water in ice. The wave‐scattering theory of Kuster and Toksoz is used to determine the effective elastic moduli, and hence the acoustic velocities. The model predicts V p and V s to be decreasing functions of both the porosity and the water‐to‐ice ratio. The theory has been applied to laboratory measurements of V p and V s in 31 permafrost samples from the North American Arctic. Although no direct measurements were made of the extent of freezing in these samples, the data are consistent with the predictions of the model. Electrical resistivity measurements on the permafrost samples have demonstrated their essentially resistive behaviour. The ratio of resistivity of permafrost in its frozen state to that in its unfrozen state has been related to the extent of freezing in the samples. Electromagnetic and seismic reflection surveys can be used together in areas of permafrost: firstly an EM survey to determine the extent of freezing and then the acoustic velocity model to predict the velocities in the permafrost. The necessary transit time corrections can thus be made on seismic reflection records to compensate for the presence of permafrost.