Abstract
Previous studies have revealed that gas compositions of fluid samples collected from southwestern Taiwan, where many hot springs and mud volcanoes are distributed along with tectonic structures, show significant variation before and after some disaster seismic events. Such variations, including radon activity, CH4/CO2, and 3He/4He ratios of gas compositions, are considered precursors of earthquakes in this area. An automatic system for continuous on-line gas monitoring and groundwater sampling was established at Yun-Shui (YS), where an artesian well located at an active fault zone in SW Taiwan, to validate the relationship between fluid compositions and seismicity. It is equipped with a quadrupole mass spectrometer (QMS) and a radon detector for in-situ measurement of the dissolved gas composition. Variations of dissolved gas compositions are transmitted to the laboratory through the internet. Furthermore, a syringe pump apparatus for the retrieval and temporal analysis of helium (SPARTAH) is also installed for off-line laboratory analysis for obtaining the detailed time-series records of helium, hydrogen, oxygen, and dissolved inorganic carbon (DIC) isotopic compositions as well as dissolved inorganic carbon and chloride concentration of water samples at this station. After continuous monitoring for several months, two substantial anomalies of multiparameter were observed prior to the significant earthquakes. This automated system has been demonstrated to be feasible for long-term continuous seismo-geochemical research in this area.
Highlights
Since the 1970s, geochemical studies have been carried in the world for earthquake precursors (Sugisaki, 1978; O’Neil and King, 1981; Sugisaki, and Sugiura, 1985; Roeloff, 1988)
This paper aims to describe the characteristics of the on-line monitoring system and off-line laboratory analysis and assess the feasibility of using the SPARTAH system to obtain high resolutions and precise measurements of different geochemical parameters in water for earthquake precursory studies in Taiwan
Groundwater flows out from a depth of ∼100 m, which was introduced into the gas-water separator for on-line monitors, while groundwater was connected via the coils of Cu tubing to a storage device for off-line laboratory analysis
Summary
Since the 1970s, geochemical studies have been carried in the world for earthquake precursors (Sugisaki, 1978; O’Neil and King, 1981; Sugisaki, and Sugiura, 1985; Roeloff, 1988). Precursory anomalies in the radon concentration of groundwater were reported before the Izu–Oshima–kinkai earthquake in 1978 and the Kobe earthquake in 1995 (Wakita et al, 1980; Igarashi et al, 1995). Preseismic changes in groundwater level and temperature were detected from the well before the 1970 M6.7 Przhevalsk Earthquake and the 2011 Tohoku Earthquake (Sadovsky et al, 1972; Orihara et al, 2014). Change in several water parameters is proposed as the precursory signals, groundwater chemistry, water temperature, water level, and radon concentration, have been reported before the earthquakes in many geological environments in Taiwan, such as hot/cold springs, mud volcanoes, and groundwater well Y. et al, 2001; Song et al, 2003; Song et al, 2005; Song et al, 2006; Yang et al, 2004; Yang et al, 2006; Kuo et al, 2006; Yuo et al, 2010; Lai et al, 2010; Chen et al, 2013)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
