Using Underground Radon to Detect Inactive Geological Faults

Germán Rodríguez Ortiz, University of Texas at El Paso


This thesis presents the results of an investigation of the concentration of radon in soil around a fault in the East Franklin Mountains in the El Paso area in West Texas. The connection between underground radon exhalations near active faults has been known for decades, but possible similar increases of underground radon levels around inactive faults have not been studied as thoroughly. Arguing that the dilatancy-diffusion model used to explain the phenomenon near active faults does not apply to the case of inactive faults, a hypothesis is formulated under which increased levels of underground radon must be present near inactive faults. To test the hypothesis a series of measurements of underground radon gas were performed around a fault in the Franklin Mountain of El Paso, Texas. The measurements found that the in-soil production of radon is indeed correlated to the existence of a fault even if it has not had any recorded activity in recent geological times. This finding seems to indicate that in non-active faults the radon production is due mainly to the radioactivity of the top soil and to the transport properties of the medium, and not to deeper seismic activity. These results open the possibility of using in-soil radon gas concentrations as an examination tool of dormant faults in inhabited areas where no other fault-detecting methods can be used.

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Recommended Citation

Rodríguez Ortiz, Germán, "Using Underground Radon to Detect Inactive Geological Faults" (2017). ETD Collection for University of Texas, El Paso. AAI10621134.