1995年兵庫県南部地震前後における神戸地下水中のSr同位体比および親石元素組成の変化

概要

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In order to investigate the chemical variations before and after the 1995 Kobe earthquake, 59 water samples from three commercial and one domestic wells in Kobe City were analyzed for ^<87>Sr/^<86>Sr isotopic ratio and concentrations of lithophile elements (Mg, Ca, Sr, Ba and U). First, we examined the influences of collection and treatment processes on chemical compositions of commercial water. We assumed that original changes of chemical features were preserved for the water samples from two of the four wells studied. Concentrations of dissolved ions in water from a well (M) appeared monotonously decreasing forl5 months before and after the Kobe earthquake. During this period, the ^<87>Sr/^<86>Sr isotopic ratio and concentration ratios of lithophile elements were kept substantially constant. Then anomalies of chemical and isotopic compositions occurred after 9 months of the earthquake. Another well (S) shows the marked anomaly of^<87>Sr/^<86>Sr isotopic ratio along with the change of chemical compositions just 3 days before the Kobe earthquake. Geochemical changes of dissolved metallic species, particularly Sr isotopes in groundwater may provide significant informations to understand the local changes of hydrological circumstances associated with the Kobe earthquake.
日本地球化学会の論文
2000-06-10