Geochemical Monitoring of the Seismic Activities and Noble Gas Characterization of the Geothermal FIelds along the Eastern Segment of the Büyük Menderes Graben

Abstract

Continuous monitoring of geochemical parameters related to gases in geothermal fields is widely used in seismically active regions of the crust. In this respect, a real time gas monitoring setup was installed near a bubbling pool in the Tekke Hamam geothermal field located along the eastern end of the Büyük Menderes Graben in Western Anatolia, Turkey. This site was chosen because it experiences frequent low-magnitude seismic activities. In this field, the discharged gas was collected with a funnel at the bottom of a pool and piped into a mass spectrometer for on-line analysis of CO2, CH4, H2, N2, H2S, O2, He and Ar. In addition to online monitoring, gas and water samples were collected from the Tekke Hamam and Kızıldere geothermal fields, the latter being also located along the eastern segment of the Büyük Menderes Graben, 4 km northeast of Tekke Hamam. During continuous monitoring from November 2007 to October 2008, significant variations were detected in the gas compositions of the bubbling pools. These variations were evaluated on a monthly basis and are being correlated with both seismic and meteorological data compiled during the course of monitoring. In addition to the gas monitoring data, a general geochemical characterization of the Kızıldere and Tekke Hamam geothermal fields is being performed on the basis of isotope analyses of both water and gas samples collected from the geothermal fields.