自記水管傾斜計

Abstract

To study the volcanic crustal deformations in the vicinity of Volcano Sakura-jima, onecomponent recording water tube tiltmeter was installed in the underground tunnel at theHiyamizu observation station which belongs to the Sakura-jima Volcanological Observatory.The recording methods of the apparatus contain two groups: instruments with visualpoint readings by micrometers, and instruments with continuous recordings by the opticalmethod.A hardend vinyl chloride tube with an inside diameter of 16 mm. And 45 meters in lengthserves as the water tube. The sensitivity on the re ording photographic paper can be changedto 0.0069 "/mm., 0.011 "/mm. And 0.013 "/mm., by the diameter of the pully.Good results have been obtained when this water tube tiltmeter was set in the under-ground zunnel where the effects of the atmospheric pressure gradient and the temperaturechange are few.