Mexico City's Smart City Tech Anticipates Earthquakes with Coastal Sensors

Mexico City has a unique advantage in earthquake preparedness, receiving advance warning of up to 90 seconds before seismic waves arrive. This crucial time buffer is made possible by a sophisticated network of sensors deployed along the Pacific coast, primarily in Guerrero and Oaxaca.

The system capitalizes on the physics of earthquakes. When tectonic plates rupture, they generate two types of waves: primary (P) waves, which travel faster but are less destructive, and secondary (S) waves, which are slower but cause the most damage. The sensors detect the P-waves first, transmitting a radio signal that travels near the speed of light to the capital. This signal arrives significantly ahead of the more damaging S-waves, especially given the distance of over 300 kilometers between the earthquake's origin and Mexico City.

The development of this early warning system, known as SASMEX, was a direct response to the catastrophic 1985 earthquake that devastated the capital. Founded by engineers, the Center for Seismic Instrumentation and Recording (CIRES) aimed to provide alerts during seismic events. Launched in 1991 with 12 coastal stations, it was the world's first public early warning system. The system has since expanded to include more sensors and states, with Mexico City's subway system being one of the first to integrate the alerts.

At the heart of SASMEX are 97 sensors along the Pacific coast, monitoring ground acceleration. Upon detecting a potential seismic event, three algorithms rapidly calculate the earthquake's magnitude. These calculations are refined based on the strength and duration of the detected signal, with different thresholds applied depending on whether the earthquake is near or far. This technological advancement allows for timely evacuations of buildings, halting of public transport, and other critical safety measures, significantly mitigating the impact of earthquakes on the densely populated capital.