Possible Locking Shock Time in 2-48 Hours

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

Automated summary

This paper reveals the precursor of inland earthquakes on an hourly scale. By analyzing the data of 23 inland earthquakes in China, it is found that when the weather conditions near the epicenter are fair, an anomalously negative atmospheric electrostatic signal can be observed approximately 2-48 hours before the earthquake occurs. The paper also demonstrates a successful single-station alarm for moderate-magnitude earthquakes and proposes a possible mechanism for the precursor signal.