also evidence from Kodiak that boats, left dry "by a drawdown, were 

 toppled when the water started to rise again, especially when the wave 

 came in with a steep, breaking front. 



Large vessels survived the tsunami. Most remarkable is probably 

 the survival of the 11,000-ton ship Chena during the slide-generated 

 waves at Valdez. All the smaller boats in that harbor were completely 

 destroyed. Also the 2,000-ton tanker Alaska Standard weathered the 

 slide-generated waves at Seward, whereas the small boats there were 

 either badly damaged or destroyed. 



The large vessels that were moored to the Marginal Pier and the 

 Cargo Dock of the Kodiak Naval Station, as well as the large timber 

 barge that was moored to Citizens Dock at Crescent City, all withstood 

 the tsunami well. However, these vessels severely damaged the dock 

 structures, particularly at Crescent City. 



It should be noted here that in other great tsunamis, particularly 

 that of the Chilean earthquake of May I96O, large ships have not fared 

 so well, especially when caught in narrow waterways where the whip-action 

 of violent surge currents carried them out of control (cf. Sievers , et 

 al, 1963; Takahasi, et al, I961). 



Many times it has been proven that the safest place for ships and 

 boats of all types during the rampage of a tsunami is the open sea. In 

 fact, a standard procedure of the seismic-sea-wave, warning system of 

 the U. S. Coast & Geodetic Survey is now to advise that ships vacate any 

 threatened port and make for open water, as far from shallow water and 

 enveloping coastline as possible (Coast & Geodetic Survey, I96U). 



A problem remains, however, in respect to ships or boats which 

 cannot generate power, or muster a crew, in time to escape the inrush 

 of a tsunami. It may even happen that the extent of advance warning of 

 the approach of a tsunami might be insufficient to warrant risking the 

 lives of crews in attempts to undock ships and head for open sea. There 

 may not be a great deal that can be done for ships and boats in such 

 circumstances . 



Primary protection for shipping, however, must come from outer 

 breakwaters or tsunami barriers when the economic issues justify barriers 

 capable of blunting tsunami attack. It is almost certain, however, even 

 with barrier protection, that very long-period, high-amplitude seismic 

 sea waves will cause overtopping and violent flushing of harbor and 

 marina basins, and that the induced currents may be powerful enough to 

 tear ships from their moorings and small-boat, landing floats from their 

 pylons. Conventional mooring facilities would probably be unable to 

 resist chaotic disorder of this kind, so that important secondary pro- 

 tection for shipping must be devised within the dock areas themselves. 



For protection of large ships, a primary requirement would be the 

 provision of elastic shock-absorbing fenders as permanent fixtures of 



370 



