Anomalous radon emanation linked to preseismic electromagnetic phenomena

Abstract. Anomalous emanation of radon (222Rn) was observed preceding large earthquakes and is considered to be linked to preseismic electromagnetic phenomena (e.g. great changes of atmospheric electric field and ionospheric disturbances). Here we analyze atmospheric radon concentration and estimate changes of electrical conditions in atmosphere due to preseismic radon anomaly. The increase of radon emanation obeys crustal damage evolution, following a power-law of time-to-earthquake. Moreover, the radon emanation decreases the atmospheric electric field by 40%, besides influencing the maximum strength of atmospheric electric field by 104–105 V/m enough to trigger ionospheric disturbances. These changes are within the ranges observed or explaining electromagnetic phenomena associated with large earthquakes.

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Time-scale invariant changes in atmospheric radon concentration and crustal strain prior to a large earthquake

Nonlinear Processes in Geophysics ◽

10.5194/npg-14-123-2007 ◽

2007 ◽

Vol 14 (2) ◽

pp. 123-130 ◽

Cited By ~ 15

Author(s):

Y. Kawada ◽

H. Nagahama ◽

Y. Omori ◽

Y. Yasuoka ◽

T. Ishikawa ◽

...

Keyword(s):

Power Law ◽

Time Scale ◽

Radon Concentration ◽

Large Earthquake ◽

Irreversible Thermodynamic ◽

Time To Failure ◽

Scale Invariant ◽

Crustal Strain ◽

Kobe Earthquake ◽

Atmospheric Radon

Abstract. Prior to large earthquakes (e.g. 1995 Kobe earthquake, Japan), an increase in the atmospheric radon concentration is observed, and this increase in the rate follows a power-law of the time-to-earthquake (time-to-failure). This phenomenon corresponds to the increase in the radon migration in crust and the exhalation into atmosphere. An irreversible thermodynamic model including time-scale invariance clarifies that the increases in the pressure of the advecting radon and permeability (hydraulic conductivity) in the crustal rocks are caused by the temporal changes in the power-law of the crustal strain (or cumulative Benioff strain), which is associated with damage evolution such as microcracking or changing porosity. As the result, the radon flux and the atmospheric radon concentration can show a temporal power-law increase. The concentration of atmospheric radon can be used as a proxy for the seismic precursory processes associated with crustal dynamics.

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Preseismic atmospheric radon anomaly associated with 2018 Northern Osaka earthquake

Scientific Reports ◽

10.1038/s41598-021-86777-z ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Jun Muto ◽

Yumi Yasuoka ◽

Nao Miura ◽

Daichi Iwata ◽

Hiroyuki Nagahama ◽

...

Keyword(s):

Crustal Deformation ◽

Radon Concentration ◽

Seismic Quiescence ◽

Atmospheric Concentration ◽

Rupture Dynamics ◽

Physico Chemical ◽

Large Earthquakes ◽

Statistical Anomaly Detection ◽

Atmospheric Radon ◽

2018 Northern Osaka Earthquake

AbstractDespite the challenges in identifying earthquake precursors in intraplate (inland) earthquakes, various hydrological and geochemical measurements have been conducted to establish a possible link to seismic activities. Anomalous increases in radon (222Rn) concentration in soil, groundwater, and atmosphere have been reported prior to large earthquakes. Although the radon concentration in the atmosphere is lower than that in groundwater and soils, a recent statistical analysis has suggested that the average atmospheric concentration over a relatively wide area reflects crustal deformation. However, no study has sought to determine the underlying physico-chemical relationships between crustal deformation and anomalous atmospheric radon concentrations. Here, we show a significant decrease in the atmospheric radon concentration temporally linked to the seismic quiescence before the 2018 Northern Osaka earthquake occurring at a hidden fault with complex rupture dynamics. During seismic quiescence, deep-seated sedimentary layers in Osaka Basin, which might be the main sources of radon, become less damaged and fractured. The reduction in damage leads to a decrease in radon exhalation to the atmosphere near the fault, causing the preseismic radon decrease in the atmosphere. Herein, we highlight the necessity of continuous monitoring of the atmospheric radon concentration, combined with statistical anomaly detection method, to evaluate future seismic risks.

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Sporadic sodium layer: A possible tracer for the conjunction between the upper and lower atmospheres

10.5194/acp-2020-1079 ◽

2020 ◽

Author(s):

Shican Qiu ◽

Ning Wang ◽

Willie Soon ◽

Gaopeng Lu ◽

Mingjiao Jia ◽

...

Keyword(s):

Electric Field ◽

World Wide ◽

Atmospheric Electric Field ◽

Fluxgate Magnetometer ◽

Ionospheric Disturbances ◽

Sodium Layer ◽

Sporadic E Layers ◽

Sporadic E ◽

Statistical Results

Abstract. In this research, we reveal the inter-connection between lightning strokes, reversal of the electric field, ionospheric disturbances, and a trigger of sporadic sodium layer event (NaS), based on the joint observations by three lidars, an ionosonde, an atmospheric electric mill, a fluxgate magnetometer, and World Wide Lightning Location Network (WWLLN). Our results suggest that lightning strokes would probably have an influence on the ionosphere and thus give rise to the occurrence of NaS, with the overturning of electric field playing an important role. Statistical results reveal that the sporadic E layers (ES) could hardly be formed or maintained when the atmospheric electric field turns upward. A conjunction between the lower and upper atmospheres could be established by these inter-connected phenomena, and the key processes could be suggested as follows: lightning strokes→overturning of electric field→different collisional frequencies for ions and electrons→depletion of ES/generation of NaS.

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