Recent Sea-Level Variations in Japan and Italy ¹

Abstract

IN a valuable memoir, Prof. Omori deals with -*o the variations in the height of the sea-level at nine mareograph stations in Japan from 1898 (in a few cases from 1894) to 1910, referred to in a note in NATURE of December 26, 1912 (vol. xc., p. 471). They are greatly in excess of any changes that might be due to variations of barometric pressure or air-temperature, and the effects of wind are probably negligible. These variations being allowed for, there remain considerable changes in the mean annual height of the sea-level at all nine stations, the greatest being a decrease in height of 22.7 mm. per year at Ayukama. In the accompa nyi ng sketch-map, the shaded areas represent the parts of Japan which are now subsiding, the boundaries inland being determined by interpolation. The figures at the different stations denote the mean annual rise or fall of the sea-level In millimetres per year. It is on the east side, to which the present depressions are chiefly confined, that the greatest depths of ocean lie and the most violent earthquakes originate.