The post seismic effect of far-field strong earthquakes of water radon and its mechanism analysis for L01 well of Lujiang geothermal hot spring

The Lujiang geothermal hot spring well No.1 is located on the Tanlu fault zone, where hydro-radon response to teleseism were observed. Nine geochemistry samples from the observation wells, geothermal hot spring wells and surface water along Anhui section of Tanlu fault zone were collected. The potential triggering mechanism was studied by analyzing the anion and isotope contents, as well as the source depth of the retrieved samples. The results show that the hydrochemical type is complex. The concentrations of Cl⁻ within L01, L03, L07 and SC wells are high, whereas the concentration ratios of \rmHCO_3^ -/ Cl⁻ and \rmSO_4^2 - /Cl⁻ are low, implying a strong interaction between the surface water and underground hot water, The L11 well has a large proportion of mixed cold water, and the depth of a heat source is low for L03. Water samples from Lujiang and Shucheng hot spring wells might come from crust, having moreinformation of deep tectonic activities, since the L01 and SC have the highest surface temperature and circulation depth of L01 is the deepest. The estimated depth is 12 km by calculating the Na-K-Mg concentrations. In addition, the results indicate that Lujiang geothermal hot spring well No.1 is dominated by vertical recharge and has a deeper heat source. Seismic waves could have caused weak regional tectonic activities, which change the supply of deep heat source, and cause the high hydro-radon concentrations observed.