Taking infrared anomalies as an example, three hypotheses and theories are popular internationally:
The first is that due to the intensification of tectonic activity in the earthquake zone, micro-cracks in the rocks and the surface of the region are opened, which makes underground radon, carbon dioxide and methane escape. Most of these gases are greenhouse gases, which will cause low-altitude atmospheric effect and greenhouse gas effect, produce abnormal temperature and even form abnormal clouds.
Second, the micro-fracture and opening of the rocks and the surface in the area make the underground hot water overflow and cause the surface to heat up. Third, after the tectonic stress is enhanced, the crustal rocks become high strength. At present, among these three different viewpoints, the first one is internationally recognized.
Extended data
According to the magnitude, earthquakes can be divided into:
1, weak earthquake: earthquake with magnitude less than 3;
2. Sensible earthquake: an earthquake with magnitude equal to or greater than 3 and less than or equal to 4.5;
3. Moderate earthquake: an earthquake with a magnitude greater than 4.5 and less than 6;
4. Strong earthquakes: earthquakes with magnitude equal to or greater than 6, among which those with magnitude greater than or equal to 8 are called giant earthquakes.
People's Daily Online-Infrared anomalies and cloud anomalies were discovered before the Wenchuan earthquake.