Atomic Energy and the Oscillation of Sea Level

Abstract

The tide-gauge records obtained at several tidal stations in Japan (Hanasaki, Kushiro, Miyako, Tomisaki, Urakami, Kushimoto and Oshima) situated on the Pacific coast were investigated by the present author for the days of 1st and 27th of March, 26th of April and 5th of May, 1954, on which the “H-bomb” tests would have been carried out at Bikini Atoll, and for the days before and after the days of assumed explosion, and the following facts were found.
(1) At Hanasaki (Hokkaido Island), somewhat' anomalous fluctuations in the height of sea level with periods of about 7 minutes and with a maximum range of about 25 cm were recorded for several hours from about 9h 20m a. m. (135°E Standard Time) of May 5.
(2) At Kushimoto (Wakayama Prefecture), on March 27, April 26 and May 5, remark-able rises and falls of sea level with a period of about 12 minutes were recorded for about two and a half hours from about 8h 40m on each of these days. The maximum ranges of oscillations were about 30 cm, 20 cm and 35 cm which occurred at 10h 15m a. m. on March 27, 10h 20m a. m. on April 26 and 10h Om a. m. on May 5, respectively.
(3) At the stations other than the two above-mentioned tidal stations, nothing unusual especially was found in the tide-gauge records.
Moreover, occurrence of a weak tsunami at Cape Erimo on the south coast of Hokkaido Island on the morning of May 5 was observed by fishermen in the vicinity of the cape.
Although it is not quite certain at present whether or not these anomalous oscillations were really caused by the effect of “hydrogen bomb” tests at Bikini Atoll, it may be probable, because the date and the time of explosion estimated from the atmospheric oscillations observed at many places in Japan coincided fairly well with that inferred from the unusual oscillations of sea level so far as they were observed.