The only danger to you in the aircraft would be what physical activity took place with structures or other solids attached to or affected by the ground movement, such as landslides or trees or wires moving, for example. That, and having a safe place to land, of course.
As @Adirondackwannabe noted, if there is enough air movement as a result of the earthquake to affect you in the air, then you are well and truly screwed. Helicopters deal with “air movement” all the time, since they some fly though hurricane force winds on rescue missions: this video was shot from a Coast Guard helicopter during a rescue mission which occurred during the real “perfect storm” that the book was written about. Winds ain’ no thang.