Radon Anomaly: A Possible Precursor of the 1978 Izu-Oshima-kinkai Earthquake

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Science  22 Feb 1980:
Vol. 207, Issue 4433, pp. 882-883
DOI: 10.1126/science.207.4433.882


Precursory changes in the radon concentration of groundwater were observed prior to the Izu-Oshima-kinkai earthquake (magnitude 7.0) 14 January 1978. The distance from the epicenter to a continuous radon-monitoring station at Nakaizu was about 25 kilometers. A sudden drop and a subsequent increase in the radon concentration recorded on 9 January 1978 were significant. The size of the spike-like change was about 15 percent. After the earthquake, a remarkable increase in the radon concentration occurred.