title: Implications of ground water chemistry and flow patterns for earthquake studies.
abstract: Ground water can facilitate earthquake development and respond physically and chemically to tectonism. Thus, an understanding of ground water circulation in seismically active regions is important for earthquake prediction. To investigate the roles of ground water in the development and prediction of earthquakes, geological and hydrogeological monitoring was conducted in a seismogenic area in the Yanhuai Basin, China. This study used isotopic and hydrogeochemical methods to characterize ground water samples from six hot springs and two cold springs. The hydrochemical data and associated geological and geophysical data were used to identify possible relations between ground water circulation and seismically active structural features. The data for delta18O, deltaD, tritium, and 14C indicate ground water from hot springs is of meteoric origin with subsurface residence times of 50 to 30,320 years. The reservoir temperature and circulation depths of the hot ground water are 57 degrees C to 160 degrees C and 1600 to 5000 m, respectively, as estimated by quartz and chalcedony geothermometers and the geothermal gradient. Various possible origins of noble gases dissolved in the ground water also were evaluated, indicating mantle and deep crust sources consistent with tectonically active segments. A hard intercalated stratum, where small to moderate earthquakes frequently originate, is present between a deep (10 to 20 km), high-electrical conductivity layer and the zone of active ground water circulation. The ground water anomalies are closely related to the structural peculiarity of each monitoring point. These results could have implications for ground water and seismic studies in other seismogenic areas.
authors: Institute of Geology, China Seismological Bureau, Beijing, China. wanggc@pku.edu.cn
authors: Wang
authors: W
authors: Guangcai
authors: Zhang
authors: Z
authors: Zuochen
authors: Wang
authors: W
authors: Min
authors: Charles A
authors: CA
authors: Cravotta
authors: Liu
authors: L
authors: Chenglong
mesh_terms: D001128:Argon / Q000032:analysis; D002118:Calcium / Q000032:analysis; D002250:Carbon Radioisotopes / Q000032:analysis; D002681:China; D002712:Chlorides / Q000032:analysis; D003903:Deuterium / Q000032:analysis; D004190:Disasters; D004784:Environmental Monitoring; D005618:Fresh Water / Q000737:chemistry*; D005844:Geology / Q000379:methods; D006371:Helium / Q000032:analysis; D008274:Magnesium / Q000032:analysis; D010103:Oxygen Isotopes / Q000032:analysis; D011188:Potassium / Q000032:analysis; D012964:Sodium / Q000032:analysis; D013431:Sulfates / Q000032:analysis; D014316:Tritium / Q000032:analysis; D014872:Water Movements
chemical_list: D002250:Carbon Radioisotopes; D002712:Chlorides; D010103:Oxygen Isotopes; D013431:Sulfates; D014316:Tritium; D006371:Helium; D001128:Argon; D012964:Sodium; D003903:Deuterium; D008274:Magnesium; D011188:Potassium; D002118:Calcium