condition to about 0. 7 for high bed resistance. Cross' own experiments 

 for the case of simulated tsunami surges travelling over a relatively smooth 

 bod (Chezy coefficient C — 98), yield a consistent result for different 

 values of surge height H 



— - — - 1.41 (D-15) 



which fortuitously agrees with Eq. (D-11). 



There remains to mention the work of Matlock et al (1962), recently 

 condensed in a paper by Reese and Matlock (1967); whose post-mortem 

 analysis of the damage caused by the Chilean tsunami at Hilo, Hawaii, in 

 i960, attempted to identify the forces and velocities of the bore, known to 

 have been responsible for a great deal of the damage. In all but one case 

 of structural failure, of the ten cases examined, the force necessary to 

 cause failure was calculated and correlated with a force based on pure 

 fluid drag, namely 



F = i Cj^ paJ- (D-16) 



in which C_ is a dimensionless drag coefficient appropriate to the fluid 

 flow and the shape of the structural obstacle, p the mass density of 

 water, A the projected area of the obstacle normal to the flow, and u 

 the stream velocity bearing on the structure. The essential outcome of 

 their study was to show that the velocities con"iputed as being necessary 

 to cause the structural failures were in a range consistent with water 

 velocities for the bore based on Eq. (D-6) or its simplification for surge 

 over a dry bed such as Eq. (D-8). 



D-6 



