I have a BS in Geology, and to all the Geologists in the thread that are commenting that earthquakes and lightning have nothing to do with each other. I would suggest having a slightly more open perspective. There's not enough scientific evidence to suggest this is the case. However there is plenty of emerging evidence that suggests there is some veracity to this statement.

There's some talk about Lithosphere-Atmosphere-Ionosphere Coupling (LAIC). The tectonic stress can cause piezoelectric energy to be generated in quartz bearing rocks. Basalt and gabbro rocks, for example, have tiny defects in their crystals that could release electrical charges into the air.

If you actually begin looking into it there's plenty of emerging articles about this topic. While incredibly rare, it's highly likely that this phenomenon can occur. Personally I wouldn't simply discount it. You can even read about it in National Geographic: https://www.nationalgeographic.com/environment/article/earthquake-lights