# Atmospheric Charge Separation Mechanism Due to Gas Release from the Crust before an Earthquake
## 2 Physical Modeling  
Earth serves as a significant source for the generation of numerous gases which are byproducts of natural radioactive elements such as uranium, thorium and potassium. These gases provide crucial insights into the Earth's interior, the conditions of the massifs in the upper crust and the geoecological environment. More than 60-70% of the general productivity of natural ionization sources is provided by ground radiation. Through ground-based measurements, gaseous discharges of various substances, including radioactive elements such as radon and its decay products, have been detected in the atmosphere prior to the occurrence of major EQs. The concentration of these gases experiences a substantial increase of approximately 4-8 times over undisturbed levels preceding an EQ. A rise in the radon  
Figure 2: Abnormal signals of atmospheric static electricity on sunny days basically emerge only 2–48 h before an earthquake (panel (**a**) shows the Beijing Ms 3.0 earthquake on 14 April 2019, with a station located 40 km from the epicenter, (**b**) shows the Rongxian Ms 4.7 earthquake on 24 February 2019, with a station located 30 km from the epicenter, panel (**c**) shows the Changning Ms 6.0 earthquake on 17 June 2019, with a station located 50 km from the epicenter and (**d**) shows the Wenchuan Ms 8.0 earthquake on 12 May 2008, with two stations located 50 and 55 km from the epicenter. The data gap in panel (**d**) is due to a power outage. In the maps on the right, the stars denote the stations and the circles denote the epicenters) [21]. concentration can be observed several days before the onset of seismic activity, reaching emission levels as high as 25 Bq/m\({}^{3}\), which correspond to an ion formation velocity of approximately Q-16 \(\times\) 10\({}^{3}\) cm\({}^{-3}\) s\({}^{-1}\). These variations persist for periods ranging from several hours to several days. Within the Earth's surface, one can identify three primary ionization sources, namely, alpha, beta and gamma radiation. However, at a distance of 1-2 m above the surface, the average intensity of ion production resulting from these terrestrial sources does not exceed 3-5 cm\({}^{-3}\) s\({}^{-1}\). Notably, the radioactivity present in the air contributes to the intensity of ion production within the lower layer of the atmosphere, accounting for approximately 3-4 cm\({}^{-3}\) s\({}^{-1}\)[22]. As shown in Figure 3, there are three main types of ionization in the tropospheric atmosphere: radioactive radiation in the Earth's crust (\(\gamma\) rays constitute the main ionization source), radioactive radiation in the atmosphere (\(\alpha\) rays constitute the main ionization source) and cosmic rays from space. The verse lines are high-energy particles from space, mainly encompassing a 10\({}^{8}\)-10\({}^{20}\) eV high-energy proton composition. Energetic GeV particles can penetrate the atmosphere to reach the ground, which can impact the molecular atoms in the atmosphere to form high-energy particles, referred to as secondary cosmic lines. Due to the geomagnetic field, the cosmic line is deflected toward the poles when it penetrates the Earth. Therefore, the intensity increases with latitude. The total atmospheric ionization rate at the ground is 9.8 cm\({}^{-3}\) s\({}^{-1}\) and the radioactivity in the atmosphere accounts for 47% of the total radioactivity, which in the crust accounts for 36% of the total radioactivity, and that of the cosmic line accounts for 17% of the total radioactivity. This suggests that at the surface, the radioactive material in the atmosphere plays a major role in atmospheric ionization [22]. Notably, \(\alpha\)-ray penetration is very poor, ranging from 1 to 8 cm, with atmospheric ionization rates ranging from 40 to 1 cm\({}^{-3}\).s\({}^{-1}\).