Hydrogeological and Geochemical Observations for Earthquake Prediction Research in China: A Brief Overview

Hydrological and geochemical changes have been studied extensively in China for the purpose of earthquake prediction since 1966. This paper gives a brief overview of the findings, which have been reported mainly in Chinese so far. Parameters studied include water level; water temperature; and radon, hydrogen and mercury concentrations. Significant changes have been observed before some large or even intermediate-sized earthquakes, among many cases that did not show any such changes. Background noise caused by other environmental variables and possible mechanisms for the pre-earthquake anomalies are discussed. Due to the complexity of earthquake prediction, much more monitoring efforts as well as sophisticated analytic and synthetic efforts are needed in the future.