The first aspect is because the essence of earthquake comes from the shock wave produced by the collision of two plates. After the shock wave reaches the ground, it will cause serious disasters, and at the same time, cracks will be formed due to plate collision, and a lot of geothermal energy will gush out from these cracks at this time. Then the water on the surface will be evaporated, and then they will rise to the atmosphere. If there is enough water at this time, it will form rain. The second theory is that earthquakes will produce a lot of dust, which will combine with water molecules in the clouds to form rainfall after entering the air. Because water molecules want to condense together quickly, they need to condense nuclei, and dust can play this role. I believe that many friends who grew up in the countryside have had this experience, that is, they used some water tanks to pick up the rain for a while. After time to clarify the water, you will find a layer of dust at the bottom of the water tank.
As a matter of fact, in my opinion, rainfall after the earthquake is not inevitable. First of all, rainfall is a regional intermittent thing. This is a natural phenomenon in a region, especially in rainy and dry seasons. Although the earthquake activity is very intense, it is still difficult to change futures directly. Moreover, the fluctuation caused by earthquake does not generate heat, and heat can only be emitted by geothermal energy through cracks caused by earthquake movement. However, such behavior has geographical restrictions and cannot be widely used. On the other hand, why does it always rain after an earthquake? It's because people won't notice it on a sunny day. Once it rains, the rescue is more difficult, and people will deepen their impression of him.