Radon Anomaly: A Possible Precursor of the 1978 Izu-Oshima-kinkai Earthquake.
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.
Wakita
H
H
Nakamura
Y
Y
Notsu
K
K
Noguchi
M
M
Asada
T
T