# SafeNet: SwArm for Earthquake Perturbations Identification Using Deep Learning Networks
## 5 Discussions
Because Rn decay can emit alpha particles, we propose a new hypothesis to explain the physical mechanisms of earthquake-induced ionospheric perturbations, as schematically depicted in Figure 13. In this hypothesis, various crustal movements in the pre-earthquake stage lead to rock fragmentation, melting, mineral dissolution, or phase change, and daughter isotopes of some radioactive parent isotopes retained in certain minerals or rocks are released in large quantities. In this situation, the Rn gas content in the area near the epicenter is abnormal before the earthquake, and furthermore the Rn gas decays quickly (half-life is about 3.8 days). During Rn decay, many alpha particles are released. The energy of an alpha particle is 5.2 MeV, and the ionization energy required by an atmospheric molecule is 32 eV. Therefore, one alpha particle is sufficient to generate 150,000 pairs of positive and negative ions, thereby creating an excess of positive airborne ions near the Earth's surface. Because pre-earthquake field ionization occurs over relatively wide areas, we suggest that the positively charged air bubble expands owing to its internal electrostatic repulsion. Furthermore, as the prevailing electric field has an acceleration effect on positive airborne ions relative to the Earth's surface, the only direction of the airborne ions is upward. Therefore, many airborne ions would rise rapidly and shorten the vertical potential difference between the Earth's surface and the ionosphere. In response, the ionospheric plasma would be expected to polarize, causing the electrons located at the bottom of the ionosphere to be pulled downward. Thus, the physical properties of the ionosphere respond to changes in the vertical distribution of electrons and ions in the ionospheric plasma. In this way, it will result in a vertical electric field, E. The electric field pushes upward current flow from the atmosphere into the ionosphere. The injected current could result in the ionosphere being subjected to an enforced electric field. The perpendicular component of the electric field causes plasma E \(\times\) B motion, which results in fluctuations in the ionosphere's density [27,61]. Moreover, the ionospheric anomalies before and after the earthquake could be positive or negative, and the probability of positive and negative perturbations is almost the same [62]. Simulations of anomalous electric fields show that if the anomalous electric field is westward, then the density enhancement occurs at the equator and the electron density decreases upward at the polarities [62]. If there is an eastward anomalous electric field, the positive and negative anomaly positions will be opposite. According to our knowledge, the anomalous electric field will be significantly different from one earthquake or different times of the same earthquake, so both positive and negative anomalies could be observed before and after the earthquake. In addition, [PERSON], et al. [63] also found that both positive and negative anomalies could occur before the earthquake by analyzing the GIM TEC of all Ms 7.0+ earthquakes in 2010. In addition, [PERSON] et al. studied the Wenchuan earthquake and also found that some of the GPS station data near the epicenter showed positive anomalies and some showed negative anomalies [64]. In the development of earthquake mechanisms at this stage, more experimental and actual evidence of radon gas generation in pressurized rocks is needed because it  
Figure 13: The proposed physical mechanisms of ionospheric perturbations induced by earthquakes. A large area of rock is broken and torn before the earthquake, after which a channel is opened to continuously release radon gas to generate radioactive decay. A gas bubble, laden with positive airborne ions generated during the process of radon decay at the ground-to-air interface, expands upward through the atmosphere, carrying up the Earth’s ground potential and eliciting a polarization response in the ionosphere.