Why is there a flash in the sky during an earthquake?

The reasons why there will be strong light in the sky before the earthquake are as follows

First, before the earthquake, the geomagnetic and geoelectric fields in the earthquake zone changed rapidly and interacted with the ionosphere in the atmosphere.

Second, natural gas, methane and other substances underground in the earthquake zone emerged from the ground along the ground cracks and were suddenly ignited by electrostatic discharge;

Thirdly, before the earthquake, the crustal rocks in the earthquake zone violently collided, rubbed and shattered in a short time, resulting in the sudden release of heat or current.

The cause of the earthquake

The reason for the earthquake is that the middle strata in process of crustal movement are squeezed or stretched. When the compressive force or tensile force exceeds the bearing capacity of the rock stratum, the rock stratum will rupture, thus releasing the energy gathered in the rock stratum and forming the ground seismic ground, which is called earthquake for short.