Frontiers in Earth Science ( IF 2.0 ) Pub Date : 2021-01-25 , DOI: 10.3389/feart.2021.635913 Ching-Chou Fu , Chun-Wei Lai , Tsanyao Frank Yang , David R. Hilton , Cheng-Hong Chen , Vivek Walia , Arvind Kumar , Lou-Chuang Lee
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