Real-time gas monitoring at the Tekke Hamam geothermal field (Western Anatolia, Turkey): an assessment in relation to lo

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Real‑time gas monitoring at the Tekke Hamam geothermal field (Western Anatolia, Turkey): an assessment in relation to local seismicity Selin Süer1,4 · Thomas Wiersberg2 · Nilgün Güleç1 · Jörg Erzinger2 · Mahmut Parlaktuna3 Received: 19 April 2018 / Accepted: 20 August 2020 © Springer Nature B.V. 2020

Abstract This study presents the results of a real-time gas monitoring experiment conducted, via the use of a quadrupole mass spectrometer, in a mofette field within the Tekke Hamam geothermal site in western Anatolia (Turkey), a tectonically active region hosting several east–west trending grabens. The study is aimed to establish a baseline gas profile of the region. Within the framework of the experiment, gas compositions ­(CO2, ­N2, ­O2, ­H2, ­H2S, ­CH4, He, and Ar) and flow rate of a mofette were monitored during two observation periods: November 2007–January 2008 and April–July 2008. During the course of monitoring, the major gas component was ­CO2 with concentration changing around 96 volume percent. Other gases, from the most abundant to the least, were ­N2, ­CH4, ­O2, ­H2S, Ar, ­H2, and He. The study produced a short-term, baseline gas profile of the region with daily/diurnal variations and temporal gas fluctuations appearing as instant signals. Although the temporal gas fluctuations did not reach the anomaly level (variations staying within the mean ± 2σ), some of the variations in more than one parameter in the gas compositions (exceeding the mean ± 1σ), accompanied by changes in the diurnal gas pulses lasting for long durations, were correlated with the seismic events selected according to the adopted seismic event elimination criteria. The variations were mainly attributed to changing gas mixing ratios in relation to porosity/permeability modifications possibly related to seismicity. Studies involving the continuous monitoring of meteorological parameters are necessary to assign these variations to geogenic events. Keywords  Real-time gas monitoring · Mofette · Quadrupole mass spectrometer · Seismic event · Tekke Hamam geothermal field

* Selin Süer [email protected] Extended author information available on the last page of the article

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Natural Hazards

1 Introduction Monitoring of physical and geochemical parameters of subsurface fluids (e.g., groundwater, soil gas, and springs) has been a widely accepted technique in search for possible relationship between crustal fluids and seismic phenomena in tectonically active areas (Thomas 1988; Mogi et al. 1989; Roeloffs and Quilty 1997; Nishizawa et al. 1998; Favara et al. 2001; Claesson et al. 2004; Perez et al. 2008; Petrini et al. 2012; Chen et al. 2014; Zhou et al. 2017). Until now, subsurface gases have provided the most valuable information in regard to the evaluation of crust–fluid interaction. Since gases, either dissolved in groundwater systems or as free gas phase emanating from fumarolic discharges, are highly mobile, it is possible that they can respond to even small crustal disturbances associated with seismicity. In this r