14 



Oceanography — The Ten Years Ahead 



areas of generation at rates sometimes faster than 

 the wind speeds by which they are produced, and 

 much faster than the rate of progress of the 

 storm centers that cause them. Also, the effective- 

 ress of the wind in producing waves depends on 

 what it has to work with; that is, over what reach, 

 and how high the sea is already. The consequence 

 is that the sea at any particular point in time and 

 space is the joint product of many, many storms, 

 some of them hundreds or perhaps thousands of 

 miles distant, some interacting with others in the 

 regions of wave generation and all being felt to 

 some extent at the point of observation. Finally, 

 as the bottom shoals toward land, its contours and 

 their orientation modify the waves which roll in 

 from the open sea, often augmenting their al- 

 ready formidable aspect. 



The importance of the atmosphere-ocean inter- 

 action to prediction problems such as the genesis 

 and life history of tropical storms is widely recog- 

 nized. To increase the accuracy of short-range and 

 long-range weather predictions oceanographic 

 parameters are being considered and feed-back 

 processes taken into account. Part of the energy 

 which drives ocean currents and generates the 

 waves at the sea surface is derived from the 

 winds; another part of the energy is transmitted 

 to ihe ocean by radiational processes which are 

 modified by atmospheric conditions. But the winds 

 and atmospheric conditions themselves depend 

 on the distribution of physical properties in the 

 ocean. Therefore, oceanic circulation and atmos- 

 pheric circulation are closely linked and are being 

 studied by the Weather Bureau to provide ulti- 

 mately a better service to the public. 



Research programs of the Army's Beach Ero- 

 sion Board and the Weather Bureau for prediction 

 and protection in relation to coastal areas are ex- 

 pected to total about $16 million and $1 million 

 respectively over the decade. 



Another deadly threat to life and property along 

 the same seacoast, because it strikes without no- 

 ticeable warning, is the seismic sea wave or 

 tsunami, long an object of study and concern to the 

 Japanese who have given it its name. Earth shocks, 

 resulting in sea bottom movement, particularly 

 frequent in the volcano-ringed Pacific, start water 

 waves traveling out from a point at the surface 

 above the center of the disturbance with speeds 

 of 400 or 500 miles per hour. Ocean wave speeds 

 are partly determined by wave length. Tsunami 

 wave lengths, due to the method by which they 



receive their initial energy, are many hundreds 

 of times greater than those produced by even the 

 most violent wind. These very long waves "feel 

 the bottom" even over the deep ocean abyss in 

 much the same way the shorter wind-created waves 

 start to feel the bottom as they reach shoal water 

 along a beach, and the effect produced is the same, 

 though magnified immensely by the proportion- 

 ately greater change in depth. The upper portions 

 of the wave begin to override the lower parts, and 

 what would be an almost unnoticeable rise of a 

 foot or two in the open ocean becomes a rise of 

 perhaps 50 feet against a coastline across its 

 path. And since these waves carry thousands of 

 miles from the point of origin, they arrive unac- 

 companied by any other phenomenon which 

 might announce the impending disaster. 



The series of waves which struck the Hawaiian 

 Islands on April 1, 1946, destroyed 173 lives and 

 $25 million worth of property. It led to the estab- 

 lishment of the Seismic Sea Warning System by 

 the Coast and Geodetic Survey, which already had 

 a network of tide gauges in strateg[ic locations 

 around much of the source region. By extending 

 the network, tying it into the network of seis- 

 mological stations, and adding accurate time de- 

 vices and instant communications, the Coast and 

 Geodetic Survey is now able to predict with high 

 accuracy the time of arrival of such waves at 

 Hawaii and elsewhere in the Pacific and to issue 

 warnings well in advance. 



That the system is not perfect, however, is wit- 

 nessed by the most recent tsunami which hit the 

 city of Hilo in May 1960, destroying 61 lives and 

 about $23.5 million in property. A major defect 

 in the system is its inability to predict the amplitude 

 of the wave, and many apparent false alarms re- 

 sult when the tsunami is so small that it arrives 

 unnoticed by the residents. By the same token, it 

 is impossible for a resident to distinguish a warn- 

 ing which may be followed by an unusually dan- 

 gerous wave. The same tsunami, produced by an 

 earthquake off the coast of Chile, showed another 

 major defect of the system. It presently provides 

 warning for only a few other areas of the Pacific 

 which may be as badly threatened as Hawaii. The 

 shores of California, Alaska, Japan, and many 

 other areas were all greatly affected and wide- 

 spread loss of life and property occurred. Much 

 more research on the phenomenon is needed, and 

 the warning system improved and extended. 



