Variation of soil gas <SUP>222</SUP>Rn/<SUP>220</SUP>Rn concentration ratios along the Balçova-Narlıdere segment of the Izmir Fault

The Bal & ccedil;ova-Narl & imath;dere segment of the & Idot;zmir Fault is an active tectonic region with high geodynamic significance. Soil gas radon (Rn-222) and thoron (Rn-220) concentration ratios were studied along this segment to evaluate their potential as geochemical indicators of fault activity. Rn-222 concentrations ranged from 440 to 32,233 Bq/m(3) and Rn-220 from 328 to 29,367 Bq/m(3). A special focus was on the Rn-222/Rn-220 ratio as a geodynamic precursor. Rn-222/Rn-220 ratios were analyzed specifically at locations where single gas anomalies were detected, allowing them to distinguish among different depths of the gas source and hence different fault processes.