284 T. Teraua and T. MATU-ZA^VA 



Sauriku Earthquakes'^ of 1896 in which 27000 lives were lost. Omori^-^ 

 early recognized the proper period of the oscillation of the bay or 

 gulf as an ini]iortant factor in determining the height of the waves 

 to be observed at such a place. Nagaoka'"'^ discussed from a mathe- 

 matical standpoint the tfTects of the sea bed on tsunami. Systematic 

 observations and theoretical investigations on the secondary undulations 

 of tides of bays and gulfs along the entire coast of Japan have been 

 carried out by K. Honda*^^^ and others. For this purpose, special 

 types of self-recording tide-gauges had been devised/^^ Waves due to 

 typhoon/''^ and also seiches ^'^^ of lakes have been studied in this 

 connexion. 



The velocity of sea-waves has been determined in many cases^^^ 

 and compared with the calculated values. For some discrepancies 

 between the observed and calculated values, explanation have been 

 proposed. ^*'^ 



It must be remarked that among the periods of long waves on 

 free coasts in cases of earthquakes as well as on ordinai-y occassions, 

 a period of about one hour is always very conspicuous, Nagaoka^^"^ 

 proposed an explanation of this peculiar fact which is based on the 

 consideration of the free elastic vibration of the earth as a whole. 



(1) T. Iki, Ho., 11 (1897). Imamura, Ho., 29 (1899). Omori, Ho , 34 (1901). For 

 fsunaini observed in the case of the Kwanto Earthquake, see : T. Ikeda, Ho., lOOB. 

 Terada and Yamaguti, Ho., lOOB (1925). T. Ito, Chikyu, 1 (1924), 70. S. Nakamura, 

 also K. Suda in their different papers and reports cited. 



(2) Ho., 34 (1900); T.S.B.K., 2 (1905;, 455. 

 {;]) T.S.B.K. 1 (1902), 126. 



(4) Honda, also with others. Pub., 26 (1908); Journ. Coll. Sci., 24 (1908); T-S. 

 B.K., 2 (1904), 222; 2 (1905), 302, 307; 4 (1907), 79; Sci. Rep. Toh., [i] 1 (1911 -12), 

 61. Terada, T.S.E.K., 6 (1912). S. Yamaguti, Jap. J. Astr. Geophys., 2 (1924), 115. 



(5) Seiji Naiiaraura, T.S.R.K., 1 (1902). 123. Honda, 2 (1905), 302. 



(6) Omori, Ho., 63B (1910); 89 (1918). Honda and others, Pub. 26 (1908). 

 Honda, J.M.S., 32 (1913), 399. K. Asakura, J.M.S., 21 (1902), 686; 31 (1912), 153; 38 

 (1919), 259; 39 (1920), 257. Z. Haghvara, J.M.S., 31 (1912), 342. Y. Ivvase, J.M.S., 31 

 (1912), 349. G. Isida, J.M.S., 34 (1915), 194, 273, 341. Kumamoto-ken Tyogaisi (^^f£), 

 quoted in J.M.S., 37 (1918), 218. H. Nagaoka, T.S. B.K., 4 (1907), 210. Saem. Nakamura, 

 J.M.S. 38 (1918), 32, 219; 39(1920), 217; T.S.B.K.,9 (1918), 548; Kisyd-zassan, 1(1918), 

 189, 278. 



(7) Cited later. 



(8) Honda, T.S.B.K., 3 (1906), 165. Saem. Nakamura, Bull. C.M.O., 3, No. 2. 

 (1902). K. Suda and Seki, U. t. S., 3 (1923), 95. 



(9) Nagaoka, T-S.B.K., 4 (1907), 113. T. Terada, T.S.B.K., 6 (1912), 260. 



(10) T.S.B.K., 4 (1907), 35. 



