Creation of the Model and Interpretation 



Having developed the algorithms for defining quasi-stationary prov- 

 inces and generating valid amplitude spectra, these methods were applied 

 to an area off the Oregon coast. The area (42°N-45*"N, 130°W-124°W) was 

 selected due to data availability and the variety of geologic environ- 

 ments represented within this relatively small area. The area Includes 

 the continental margin (shelf and slope), Astoria deep-sea fan, Tufts 

 Abyssal Plain, Gorda Rise spreading center, Blanco Fracture Zone, the 

 Cascadla Channel and numerous seamounts. All spectral estimates were 

 generated from data collected on the SASS multlbeam sonar system by the 

 U.S. Naval Oceanographlc Office. Only center beam depths were used In 

 this portion of the analysis. In order to simplify processing. 



Figure 5-7 compiles the results of the combined province-picking 

 and spectra -gene rating procedures. The areas delineated by the various 

 shading patterns represent stationary provinces with similar ranges of 

 the a statistic; that Is, the amplitude of the component sinusoid at 3 

 wavelength of one kilometer. In cases of coincident values at crossing 

 lines, a simple average was taken. Ignoring for this analysis the 

 effects of anlsotropy. In many cases, provinces separated In the prov- 

 ince-picking procedure became recomblned In the final spectral model. 

 Indicating that the provlnclng algorithm used Is more stringent than the 

 levels selected for presentation. 



Within each of the larger provinces, the spectral slope parameter 

 (b) estimates were averaged and these values shown within the provinces. 

 The standard deviation of all estimates within any province was less 

 than 0.1 In all but one case shown. There Is one province in which the 



63 



