To forecast when and where strong earthquakes are likely to occur, seismologists usually apply statistics to monitor how seismic activities evolve through time. However, this method often fails to anticipate the time and magnitude of strong earthquakes. Although earthquake forecasting has been traditionally focused on mechanical quantities (e.g., stress, strain, seismicity) and has viewed their variations mainly as signs before large events, a different school has developed for decades outside the field of seismology, dealing with quantities considered as observable tracers, such as electromagnetic and chemical quantities. Those non-mechanical phenomena appear rather exotic to the mainstream community of seismologists. Such phenomena can be observed days or even weeks before strong earthquakes occur. In addition, it has been statistically reported that electromagnetic precursors are the most promising methodology for short-term earthquake forecasting.
The initiative is rationalized via a subtle atomic-level defect-based mechanism for explaining a variety of earthquake precursors, building on decades of laboratory experiments in physical chemistry and solid-state physics. The theory suggests that, as stresses build up in tectonic plates before seismic activity, electron-hole pairs are generated in the Earth’s crust. The electrons are confined to the stressed rocks, but the positively charged holes flow out into the surrounding, less stressed rocks, producing electrical currents that can travel over large distances. These currents in turn can trigger wide-ranging secondary effects ranging from unusual low to ultralow electromagnetic radiation, to emissions of spectroscopically distinct thermal infrared from the Earth’s surface, to changes in the atmosphere and ionosphere.