Continuous soil gas radon monitoring in real time with improved solidstate detector is carried out in south-central and southern Taiwan. The time series register spike-like anomalies which could be precursors of earthquakes. Monitoring stations located in a brecciated zone of active fault at Taiwan 3 and faults at Taiwan 1 showed drastic variations of radon when the terrain is stressed before the onset of earthquake. In contrast, the spectrum recorded at a station sited on a craton Akron 1 which is sited on a craton shows no significant radon variations. To actually prove that the variation of the time series is related to stress, a fourth station was anchored in a sand column (209 L) with exactly the same type of radon detector system. The time series recorded in this manner shows higher background level and spikes of high radon counts as it is stressed. Temperature and moisture variations are not affecting radon counts.

The mineralogical transformations of Fe phases induced by an acid-tolerant, Fe(III)-and sulfate-reducing bacterium, Desulfosporosinus sp. strain GBSRB4.2 were evaluated under geochemical conditions associated with acid mine drainage-impacted systems (i.e., low pH and high Fe concentrations). X-ray powder diffractometry coupled with magnetic analysis by first-order reversal curve diagrams were used to evaluate mineral phases produced by GBSRB4.2 in media containing different ratios of

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Laboratory experiments were performed to help understand the fluctuations and the spike-like anomalies of Rn in a time series that was recorded continuously at monitoring stations. One of the experiments indicated that Rn is adsorbed on the surface of sand particles and can be liberated with minor changes in the physical conditions of the containing medium. Another experiment indicated that the liberation of ultra-trace Rn, adsorbed on the surface of sand, was not very sensitive to small temperature and pressure changes but was responsive to the flow of carrier gases. Among the carrier gases tested, CO 2 was preferred because it has a boiling point similar to that of Rn. However, all other gases that are inert to Rn can also be carrier gases. Temperature variation in the supra soil layer can be measured fairly accurately inside double-insulated PVC pipes that also house the Rn detecting system. Temperature variation appears to be related to localized strain heating that is a part of the earthquake energy variation cycle. Up-flow of soil gas, caused by the strain heating, induced the sudden release of Rn, which thus appears as a spike-like anomaly. The migration of soil gases is expected to follow the thermal cycle corresponding to each earthquake cycle. Therefore, the spike-like anomalies can be used, in conjunction with the temperature variation cycle, as time markers to forecast the time, place, and magnitude of a coming earthquake.

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