Possible Locking Shock Time in 2–48 Hours

An hourly scale precursor of inland earthquakes (EQs) is revealed in this paper. Several EQ cases China have been reported. As indicated by a table listing 23 EQs and their shock time, epicenter location, magnitude, near-epicenter weather conditions, start time duration, when the conditions are fair near epicenter, an anomalously negative atmospheric electrostatic signal readily observable approximately 2–48 h before occurs. Moreover, successful single-station alarm for nearby moderate-magnitude demonstrated, possible mechanism proposed. The change field during process explained as release radioactive gases from subsurface into atmosphere via large (regional-scale) preexisting microfractures rock at source depth. These considerably ionize atmosphere, separated positive ions establish special macroscopic electric field. final critical stage may indicate stable tectonic process.