132 ART. 3. B. KOTiJ : 



piain to be 70 km., while in the present area it is about 52 hn., 

 the maximal positive and negative w^arpings in 1891 being 767 

 and 308 mm. respectively. Perhaps these values of radii indicate 

 the limit of sustainment of local cowpetent structurG of the earth's 

 supercrust. 



Abnormal cases of the curves of equal subsidence in the 

 present area are not rare. The flat- topped headland of Sakkabira, 

 325 ?w. liigh, facing the buried strait of Séto, is crowded with 3 

 curves (-700, -600, and -500 mm.) of high value (s:^<? Sketch-map, 

 PL XIII.) . The lapilli-laden top sunk down in step-fault to- 

 ward the island of Sakura-jima. On the southwest slope of the 

 island, the hencli mai'ks with -900, -800, and -800 mm. may be 

 attributable to slips of terrene when the ground shook with intense 

 succussory motion.^^ One point (bench mark No. 21) on the north- 

 west slope is extraordinary in its being raised 2100 mm. from the 

 former level, and this is tlie only point wliich made positive 

 movement, and moreover of very high value. 



The last and the greatest subsidence of 1 J 00 mm. occurred 

 at Shira-hama on the northern shore of the island (see Sketch-map 

 PI. XIIL). On the island of Héda-Kojima near the opposite shore, 

 a negative value of 1,000 ??2?». was measured. Between the last 

 two, and 3 km. off shore from Shira-hama, taken in conjunction 



1) The tilting of a portion of volcanic cone during the activity seems to be not very rare, 

 one instance being in Hawaii in 1868. Faiüt-sUps along j)er?2>^'e»"«i and radial fractures of a 

 volcano hai^pcned during, or as a cause of the great Hawaiian earthquakes of 18G8. Evidences 

 collected by H. O. Wood seem to show that they were tectonic, rather than volcanic, earth- 

 <]uakes. That the disturbed area was about 375,000 sq. miles, points to the fact that the depth 

 of origin must have been considerable, and that it gave rise to important oceanic sea waves. 

 JhdI. Sels. Soc. Avierlm, Vol. ÏV. 1914. 



Tn passing, it may bo mentioned that the destructive volcanic earthqiiakes of Sakura-jima 

 on January 12tli, 1914, were recorded in Tokyo (1,000 km.), and in Laibach in Austria. Xaturt, 

 1914. The writer has been long since inclined to think that the volcanic and tectonic earth- 

 quakes are by no means easy to separate. We must now take into consideration the crypto- 

 volcanic earthquakes which may eventually cause subaërial volcanic manifestations. 



