DE VELOPMENT OP SETSMOL OG Y IN JAPAN 285 



On another occasion/^ ^ he also snggested a possible influence of an 

 ocean current such as the Kurosiioo on the generation of some long 

 waves observed along the Pacific coast. 



Mareograms obtained at numerous stations on the occasion of the 

 recent great earthquakes have been collected by the E.I. C. and pub- 

 lished in Eeport No. 100 B, which will be of great value for future 

 investigators. Terada and S. Yamaguii in the same volume discussed 

 some of these records and called attention to some points of geophysi- 

 cal moment. An interesting compilation of the facts observed concern- 

 ing the destructive sea waves experienced on the coast of Sagami and 

 Aw^a is reported by T. Ikeda, in the same volume of the Report. ^^^ 

 It was, indeed, a very lucky incident that the general bwqW of the 

 sea level due to the sea wave was just cancelled by the upheaval of 

 the coast, otherwise the damage caused by the tsunami would have 

 been immeasurable. 



The most difficult mathematical problem on the mode of genera- 

 tion of tsunami by an abrupt change in the sea-bed has been treated 

 by Keizo Sano and K. Hasegawa/^^ and ap)plied to some actual ex- 

 amples with success. 



Eecords of sea-shocks have also been described in some cases. "^^^ 

 Phenomena of earthsounds have been studied by Omori^'^ who found 

 that sounds are most frequently noticed in mountainous regions, 

 whereas they are rarely or only weakly heard on alluvial plains. 

 Sounds heard in strong earthquakes^*'^ have often been described and 

 discussed. Though tliere are many cases in which the directions of 

 the apparent source of sound converge toward the epicentre, cases have 

 not also been rare in which the sound was heard to come from 

 opposite directions. No serious attempt has yet been made to eluci- 

 date the physical nature of this kind of sound, since the earliest one 

 by C.G. Knott. 



(1) T.S.B.K., 1 (1902), 126. 



(2) See also T. Ito, Chikyu, 1 (1924) 70. 



(3) Bull. C.M.O., 2, No. 3 (1915); T.S.B.K., 8 (1915), 187. 



(4) Miscall. Art. U.t.S., 3 (1923), 127. Suda, U.t.S., 3 (1923), 138; Special 

 Rep on the Tazima Earthquake, (1925). 



(5) Oinori, Ho., 22A (1908); 57 (1906) ; 68B (1910) ; 94 (1921). N. Kanahara, Ho., 

 35(1901). T. Hiki, Ho., 38 (1902). Anonym., J.M.S., 21 (1902), 640. 



(6) Miscell. Art., J.M.S., 32 (1913), 300; 35 (1916), 150; 40 (1921), 36. G. Isida, 

 J.M.S., 34 (1915), 61. Saem. Nakaniura, J.M.S., 36 (1917), 67; 37 (1918), 390; 38 (1919), 

 41; 41 (1922), 629; 42 (1923), 1. K. Taguti, U.t.S. 4 (1924), 199, 



