ANOMALOUS MIGRATION OF SHALLOW GROUNDWATER AND GASES IN THE BEIJING REGION AND THE 1976 TANGSHAN EARTHQUAKE

The character and cause of blowing out of gases and emission of sound from dry wells and of water becoming muddy and changing of level in water wells of the Beijing region immediately before the 1976 Tangshan Earthquake and its strong aftershocks are investigated. These phenomena, taken as possible precursors of the earthquakes as well as the motivating force, mecllanism, geological background and material sources of the anomalous migration are discussed. Besides, the paper also deals with the relation between these anomalies and the Ta-ngshan earthquake and the significance of the study of groundwater as far as earthquake prediction is concerned.No gaseous gushing from great depth in considerable quantities appeared so that migration should be regarded only as the migration of shallow groundwater and gases. This is referred to the consequence of the action on certain hydrogeologiteal structures of an impulse-like extra tectonic stress field on the active faults in the Beijing region under an unified regional stress field. The present authors suppose that further studies of the anomalous migration of groundwater and gases possibly may be fruitful to earthquake prediction work.