Yuri A. Taran

A simple method based on the phase equilibrium between gas bubbles and water is developed for the determination of the relative gas content in bubbling springs. For the calculation of the gas‐water ratio it is necessary to know only the concentration of one of the “atmogenic” components (N₂, Ar, or Ne) in a gas sample from the gas analysis. The total gas content calculated by this method can be used for the gas geothermometry and for the estimations of the gas fluxes and water flow rates from mineral and thermal springs.

Chemical and isotopic analyses of waters from 4 thermal springs of the Guerrero Pacific coast, the most seismically active area in Mexico, were performed weekly during a period of 1.5 years (October 2002–March 2004). Within the same time interval more than 200 earthquakes with 3.8 ≤ M ≤ 5.3 occurred in the area. The data display several anomalies in Cl⁻, SO₄²⁻, δD and δ¹⁸O, always immediately after an event, with a relaxation time of 3–4 weeks. The responses occurred only to earthquakes with the estimated epicenters very close to the location of a spring. These results indicate that: 1) at least for earthquakes with M < 5.3 within the Guerrero “seismic gap” there were no precursors in the chemical (ionic) and isotopic composition of thermal waters (on a weekly basis); 2) two groups of springs near Acapulco, Dos Arroyos and Paso Real, are sensitive to seismic activity and therefore further monitoring of these springs may help to unravel the mechanisms of the “hydro‐seismo‐interaction” in the area.