GEOCHEMICAL AND HYDROLOGICAL OBSERVATIONS FOR EARTHQUAKE PREDICTION IN JAPAN

Several research groups have made efforts to accumulate reliable data on various geochemical and hydrological parameters for periods longer than 10 years. The data accumulation has enabled them to characterize background fluctuations in the data and consequently to examine their relation to earthquake occurrences without prejudice. As a result, a n umber of earthquake-related anomalies have consistently been identifie d in various geochemical and hydrological observations, suggesting tha t they are sensitive indicators of earthquake occurrence. Comprehensiv e monitoring based on multicomponent and multi-station observations ha s begun to result in the detection of more reliable precursory phenome na which appeared simultaneously in two or different kinds of observat ions at several stations.