Hi 2 cents. A recent report published by the National Research Council estimates that between 15,000 and 21,000 deaths each year are the result of long-term exposure to radon gas. (Samet et al, 1998).

High levels of radon have been discovered in homes in every state, and found in more than 70,000 schools in use today across the country. A nationwide survey of radon levels indicates that nearly one in five schools has at least one classroom with high radon levels (EPA, 1994).

As you can see radon gas can and is found just about everywhere. Researchers at Bad Bramburgh in Germany have been monitoring the local springs for radon and CO2 levels since 1989, with improved equipment installed in 1992. The region is subject to numerous microearthquakes (M<4.0), which on some occasions occur at such high frequencies as to be considered “swarmquakes”. Over the last five years they have found that radon anomalies are associated with seismic events. Unfortunately from the predictive point of view these anomalies may be noted before, during, or after an earthquake.

Despite not being suitable for prediction of seismic events, the radon anomalies observed at Bad Bramburgh have produced some useful information about the mechanism by which radon levels increase. Measurement of CO2 has shown strong correlation between concentration of the gas and that of Radon. It is suggested that tectonic stress-strain triggers CO2 outgassing which, in turn, acts as a carrier for Radon gas. The d13C values (-3.5 to -3.7‰) of elevated CO2 concentrations confirm that it does indeed come from old groundwater rather than the more surficial groundwater which accounts for 20-40% of spring output.

However one of the best indications and documented case of radon gas being seen before an earthquake was for the Kobe, Japan quake in 1995. Over the last twenty years the University of Tokyo and the Geological Society in Japan have monitored radon levels in groundwater in an effort to predict earthquakes in eastern Japan. One such well is located in the southern part of Nishinomiya city, about 30 km NE of the epicenter of the M=7.2 Kobe earthquake of 17 Jan 1995. The well was first monitored between 26 Nov and 02 Dec 1993, with continual monitoring starting on 27 Oct 1994.

During the 1993 observation period, concentrations of radon were stable at 20Bq/l. By the end of Nov 1994 levels had increased to 60Bq/l. On 7 Jan 1995 a huge increase in radon concentration was observed (to ca. 250Bq/l). These high levels dropped suddenly on 10 Jan, one week before the earthquake. By the time of the earthquake levels had returned to about 30 Bq/l, levels confirmed when the station came back on-line on 22 Jan (monitoring equipment had been damaged by the main shock).

The researchers have examined other possible reasons for the observed increase in Radon levels, but no satisfactory alternate explanation could be found. Over the period of well-monitoring ground water temperature remained almost constant (±0.2°C), and there was no significant rainfall which might have affected the aquifer. Atmospheric pressure is known to have little effect on radon concentrations, so meteorological explanations were also unlikely. Take Care…Don in creepy town