出版者

日本測地学会

雑誌

測地学会誌 (ISSN:00380830)

巻号頁・発行日

vol.22, no.2, pp.65-76, 1976-09-25 (Released:2010-09-07)

参考文献数

11

---

A new gravimetric network, named the Japan Gravity Standardization Net 1975 (JGSN 75), was established and new gravity values were determined on the basis of the International Gravity Standardization Net 1971 (IGSN 71). A reliable gravimetric net has been organized in Japan by combining results of the GSI pendulum and gravimeter measurements by the Geographical Survey Institute and gravity values were determined in the Potsdam system referring to the value at the old pendulum station in Tokyo. The IGSN 71 published in 1974 contains 16 common stations with the national net. If the old reference value in Tokyo has no error, a discrepancy in gravity values at every common station must be equal to -14.0 milligals; a correction to the Potsdam absolute value. The present comparison showed that the discrepancy took mostly a constant value within a range of ±0.06 milligals. The mean value and the standard deviation were -13.80±0.03 milligals for the most districts and -14.00±0.03 milligals for the Kyushu District. No systematic inclination against the gravity value was found. This means that the scale of the Japanese gravimetric net agrees well with that of the IGSN 71. Therefore, the gravity value hitherto adopted in Japan can be converted into new one based on the IGSN 71 only by adding a constant value. New gravity values were obtained for 122 stations throughout the country and are given in this report. These are the results of repeated measurements including many new ones with LaCoste & Romberg gravimeters of which calibration constant values were corrected with our pendulum or the IGSN 71 results. A relative accuracy in this net is considered to be ±0.035 milligals and an absolute accuracy is the same as that ofthe IGSN 71. The JGSN 75 will serve as the framework of the gravimetric net in the country and should be used for all gravity works. The old Potsdam system values in Japan should be changed into new ones based on the JGSN 75.