The earthquake that shook Mexico City could not have chosen a more vulnerable target. The capital city is located in the center of the world's most populated area. Some 18 million people, one fourth of the nation's inhabitants, are jammed into a mere 890 square miles, roughly 1% of the predominantly rural area. It is estimated that nearly one third of all families in Mexico City live huddled together in a single room and the average family has five members.

Besides being a densely populated area, Mexico City was founded on a shaky geological base that makes it specially susceptible to tremors. The first human settlements were made on the soft, humid clay of an old lake bed. The city has been constantly sinking through the years and some buildings are even tilted sideways, therefore having a greater risk in case of earth movements.