c. Where the land is extremely flat and inland flooding is 

 extensive. 



The runup elevation determinations for these cases can be made as discussed in 

 paragraphs 38 and 39. 



38. The simulation of tsunami penetration into a river, including the 

 prediction of bore formation, can be made using the method of characteristics 

 (Henderson 1966). Horiguchi (1966) presents a scheme, based on the method of 

 characteristics, for computing tsunami penetration into bays and river 

 branches including prediction of bore formation. 



39. Where dunes prevent flooding, except through inlets or where the 

 land is extremely flat and inland flooding is extensive, a land flooding 

 numerical model can be used to determine runup. A model of this type which 

 incorporates the effects of bottom friction and irregular topography has been 

 developed by Houston and Butler (1979). 



Runup Determinations Between Listed Sites 



40. The tsunami wavelengths are so great compared to the length scale of 

 irregularities in the coastline that linear interpolation may be used to de- 

 termine 100- and 500-year elevations at locations between the sites shown in 

 Plates 1-77. 



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