Appendix E 



In Chapter 6, a simple model of an anisotropic surface was created, 

 and the variation of Its spectral characteristics as a function of azi- 

 muth was derived analytically and confirmed by empirical results. The 

 surface was constructed by generating a random signal of known spectral 

 properties and extending each value of the series into the second dimen- 

 sion. In the resulting relationship, 



A = a(9).s^^®^ 



The proportionality factor a(9) was shown to vary as a sinusoid and b(9) 

 remained constant over all 6. Results from multibeam-sonar-derived 

 bathymetry indicated that this simple model is adequate to describe some 

 actual surfaces on the earth, such as the Gorda Rise spreading center. 



Beyond this very simple model, a more elaborate surface can be gen- 

 erated by summing several signals of differing characteristics at a 

 variety of orientations. If one assumes that the simple corrugated 

 surface presented in the elementary model of Chapter 6 is the result of 

 a dominant, unidirectional process, then these composite surfaces would 

 represent areas of the sea floor where several geological processes have 

 been active, perhaps acting in different directions. The Gorda Rise, 

 particularly at the ridge crest, is dominated by the processes associ- 

 ated with crustal formation, and its relief does appear to conform to 

 the one-process surface model. 



The relief of the Mendocino Fracture Zone shown in Figures 4-7-10, 

 although only represented by spectra from two azimuths, indicates a 



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