wave reached an estimated maximum surge elevation of 530 meters (1,740 

 feet) on the opposite side of the bay, and generated a 61 -meter -high 

 wave seaward in the bay. Waves were also generated by icefalls in 

 Yakutat Bay, Alaska, in 1845 and 1905. Jorstad (1956), as referenced 

 by Wiegel (1964), reported on landslide-generated waves in Tafjord, 

 Norway, in 1718, 1755, 1805, 1868, and 1934. 



An example of a wave generated by a shoreline slump is given in 

 Berg, et al. (1970). A survey of the Valdez, Alaska, area after the 

 March 1964 earthquake showed that the water depth at the end of the 

 Valdez Dock had increased from 9 to 37 meters (30 to 120 feet), destroy- 

 ing the dock. Also, at a small-craft harbor breakwater, the water depth 

 increased from 2.7 to 27 meters (9 to 90 feet), destroying the breakwater. 

 The owner of a fishing boat, heading toward the Valdez Narrows from the 

 open sea, reported a wave 10.7 to 15 meters (35 to 50 feet) high, in the 

 narrows, which dispersed after passing the narrows. 



The first wave to hit Valdez was generated by the slump of the 

 waterfront, and the second wave by the slump of a shoreline area some 

 distance away. After about 5 to 6 hours, a third wave arrived, followed 

 more than 2 hours later by a fourth wave. These later waves apparently 

 resulted from some reflection or resonant effects within Prince William 

 Sound . 



Ambraseys (1960) indicated that the tsunami of 9 July 1956 in the 

 Greek Archipelago was probably produced by a series of landslides on the 

 steep banks of a submarine trench. The wave had an amplitude of 30 meters 

 (100 feet) near its source. Striem and Miloh (1975) report that tsunamis 

 have probably been generated by slumping of the continental slope off the 

 coast of Israel. Van Dorn (1965) indicates that tsunamis generated from 

 this type of source appear to be fairly localized and will not be large 

 at long distances from the source. The generating mechanism is extremely 

 inefficient, and only about 2 percent of the potential energy of a falling 

 or sliding weight is converted into wave energy. 



4. Explosions . 



An explosion acts as an impulsive-generating mechanism which generates 

 dispersive waves from a point source. Data from nuclear explosion Baker 

 at Bikini Atoll in 1946 show that the wave height is approximately in- 

 versely proportional to the radial distance from the point of origin; 

 i.e., Hr = constant where H is the height of the wave, and r is the 

 radial distance from the point source. At a radial distance equal to 

 35d, where d is the water depth, the relationship changes slightly, 

 with the wave height decreasing less rapidly. Wilson (1963) discusses 

 data on wave dispersion. 



The height of a wave generated by an explosion has been shown to be 

 dependent on the depth of the explosion charge. Van Dorn, Le Mehaute, 

 and Hwang (1968) show that two critical depths exist which will produce 

 the highest waves for any given explosive charge. The critical depths 

 are dependent on the charge yield, given in equivalent pounds of TNT. 



Extensive material is available on waves generated by explosions, 

 and will not be considered further here (see Smith, 1967). 



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