Mexico City faces unique seismic risk due to its particular geology. The capital was built over Lake Texcoco, whose ancient soft clay lacustrine layers have properties that significantly amplify seismic movements.
When seismic waves generated in Pacific subduction zones (350+ km away) reach these soft layers, their amplitude increases dramatically. This means an 8.0 magnitude earthquake in Guerrero can cause more damage in Mexico City than in closer zones with better geology.
The natural vibration period of Mexico City's subsoil is 2-3 seconds, matching the periods of many 6-10 story buildings. This resonance causes exaggerated oscillations in mid-rise structures, explaining why more damage occurred in these heights during 1985 and 2017.
Mexico City residents should be aware they live in an extremely high seismic risk zone. Investment in structural reinforcement and insurance is highly recommended.