The correct answer is - The coast of Mexico is on the edge of two tectonic plates, which results in frequent earthquakes.
Mexico is situated on a location where the boundaries of few tectonic plates are, the big North American tectonic plate, the smaller Cocos tectonic plate, and the miniature Rivera tectonic plate, also in close proximity is the boundary of the Caribbean tectonic plate. All of this tectonic plates are moving, they collide and submerge, so there's constant activity, which contributes to frequent earthquakes along their borders since Mexico City is pretty close to this zones it feels the effects of the earthquakes very regularly, and also has once that are very close to the city itself because the crust is split in multiple mini plates where earthquakes very often occur as well.
