TRI': (HiEAT ERUPTION OF SAKUKA-.IIMA IN 1914. 133 



\vith the high negative value at Cape Osaki (-894), there Kes 

 amidst the ]^>ay of Kagoshima an hypothetical and geometrical 

 centre (marked with a cross, x, in PL XIII.) around wliich the 

 lines of equal subsidence describe concentric circles with a radius 

 of 52 km. The point is presumably the maximal locus of sub- 

 sidence, which can only be proved by later soundings. 

 Cause op ^j^i^q ]^qI^ mobilc layer or 0. Ampfeee;e's under- 



SUBSIDENCE -^ 



current^ ^ was forced up under hydrostatic pressure 

 through the vents in Sakura-jima in the form of ' live ' lava, and 

 the cold heavy crust sunk down to compensate tJie mass defect, which 

 produced on the surface the effect in the form of a kettle- shaped 

 depression. 



That the negative movement of terrene has not yet come to 

 a standstill, but is still progressing downwards, can be unequi- 

 vocally proved by the differences of values fi'om the first and the 

 second recent levelings. The first was performed during July and 

 August, 1914, and the second during February, 1915. From the 

 values of the second levelings given on bench marks {see PL XIIL), 

 we lind where the high values obtained in the first are cor- 

 respondingly high in the second. The maximum depression'^ of 

 bay shore at Cape Osaki with -894 mm. is now augmented by 

 -O^jo mm. during an interval of 215 days, the hypothetic centre 

 still remaining in the same locus. 



Should the settling continue in the same fashion in the near 



1) ' Ueber uns Bewegnngsbild von Faltengebirge.'. Jahrb. d. k. k. Geol. lltlchsanstalt, \o\. 

 5r., 1900. 



Modern views on the formation of mountains based on the Pratt-Hayford principle of 

 isostasy are at present widely discussed in various scdentific publications, and the general ten- 

 dency on this line of study is concisely depicted in K. Andrée's 'Ueber die Bedingungen der 

 Gebirgsbildung,' Berlin, 1!J14. 



2) For instance, -(055) expressed in the term of iraiK affixed to the former value 

 -894 )/u/-. at Cape Ôsald. See PI. XIII. 



