175° was about the most easterly direction from which waves could 

 have produced the observed damage pattern o From more easterly directions 

 the waves probably would have resulted in damage to the Long Beach Break- 

 watero Consequently, it appears that the damaging waves approached San 

 Pedro Bay from directions within tlB narrow sector from 175 to about 

 185° o For directions west of 185° the effect of refraction around Cata- 

 lina Island considerably reduced the wave force on the breakwater o 



Figure 9 shows that the refraction factors increase progressively 

 toward tte east end of tte detached breakwater from 0o37 between ortho- 

 gonals a and b to I065 between orthogonals f and g with corresponding 

 heights varying from 10 to about 4-5 feet 5 disregarding interference 

 between wave trains o 



Unfortunatnelyc, actual riBasureraents of wave height and period at 

 San Pe dro Bay during this storm were not made^^ but the direction of 

 wave approach was observed by means of a transit from Pto Fermin near 

 the westerly end of San Pedro Breakwatero This observation indicated 

 that waves came from the southwest concurrentl^r with waves from the 

 southeastj and that the southwest waves appeared to be the largero 

 Although,, it is impossible to determine without obserirations of wave 

 period whether or not one train of waves was southern swell arriving 

 simultaneously with the waves from the tropical stormy the observed 

 directions of wave approach and distribution of damage can be fully ex- 

 plained by the tropical storm waves alone = 



Since waves from a tropical storm are propagated radially from the 

 storm's center^ there is a certain amount of variability in direction 

 from which the ■e'/aves may come o The higher waves arriving at San Pedro 

 Bay were probably generated near the center of the storm^ but at the 

 same time son© waves ware being generated by the weaker winds nearer 

 the east side of the storm just off the coast ^ and these; smaller waves 

 approached Long Beach from directions which were more to the southeast. 

 Having less height and shorter periods they experienced little re- 

 fraction in crossing San Pedro Shelf and reached the breakwater retain- 

 ing their original directiono On the other handy the large waves from 

 the long effective fetch approaching from directions between 175° and 

 185c were refracted most over San Pedro Sea Valley so that the wave 

 crests in the vicinity of the breakwater were oriented in such a way 

 that the waves appeared to come from directions more twoard the southeast. 



S ummary and Conclusion s 



The characteristics of waves destructive to the harbor breakwaters 

 in the Long Beach-San Pedro area have been examined o As a result of re- 

 fraction over the complicated bottom topography in San Pedro Bay this 

 wave energy was concentrated at certain parts of the breakwaters o The 

 refraction effect of the bottom topography upon waves from the tropical 

 storm was similar to that for southern hemisphere swell but less pro- 

 nounced because the tropical storm waves had shorter periods o 



15 



