back| radon observation and earthquake prediction |
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| why | Uranium(238U) repeats the radiative decay and become stable lead(206). Radon(222Rn) is the gas that produce from the decay of Radium(226Ra). Radon dissolve to underground water and also it's half-life time is 3.8 days. |
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| The distotion accumulates during the base rick before the earthquake, and the radon concentration in underground water increase/decrease for new cracking occurs during the rock, because the surface area of underground water and rock touck will be changed. |
| Observation system | Radon observation system was used with the underground water in Gifu Pref. |
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Radon observation system of "underground water radon detector" |
| co-seismic signal | The radon
concentartion and temperature of fault water are being measured
with the underground of 1,000 m depth of Kamioka mine, Gifu Pref.
The radon concentration increased sharply, and water temperature has fallen down at the same time as the occurrence of the Hyogo South Earthquake on Jan. 17,1995. Also the similar change was observed even the Hokkaido East offing Earthquake on October 4, 1994. |
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| pre-seismic signal |
The radon concentartion in underground water increased before the earthquake, with the well inside Nishinomiya-shi,Hyogo Pref. The radon concentration reached ten or more times for usual value, before one week from earthquake. Pre-seismic radon change was observed on Great Hanshin-Awaji Earthequake. |
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