Magnitude 5.6 earthquake shakes southern Mexico, triggers Mexico City alarms

A magnitude 5.6 earthquake struck southern Mexico on Monday morning, shaking communities near Pinotepa Nacional in Oaxaca and setting off the capital’s earthquake alarm as officials moved quickly to check for injuries and structural damage. The quake’s epicenter was about 24 kilometers northwest of Pinotepa Nacional, and its shallow depth, measured at 9 kilometers, made it the kind of event that can produce strong surface shaking even when the initial damage tally remains limited.

President Claudia Sheinbaum said there were no immediate reports of victims or damage, while Oaxaca Governor Salomón Jara said local authorities were evaluating possible damage and urged residents to remain calm. The Government of Oaxaca said it was maintaining preventive surveillance and coordination after the tremor, reflecting the standard posture in a state that sits close to some of Mexico’s most active seismic zones.

Mexico City felt the effects immediately. The earthquake alarm was triggered in the capital, prompting evacuations from buildings and reminding residents far from the epicenter that a southern quake can still set off an urban emergency response hundreds of kilometers away. That alarm system is part of the country’s broader readiness framework, designed to give people a few seconds to move into safer positions and clear vulnerable structures when shaking is detected.

By 8 p.m. Monday, the Servicio Sismológico Nacional had registered 206 aftershocks from the quake, with the largest measuring magnitude 4.1. The sequence turned the morning tremor into a developing seismic episode rather than a single isolated jolt, the kind of pattern officials watch closely because aftershocks can reveal stress along the fault system and complicate damage checks in smaller towns and rural roads.

UNAM’s Institute of Engineering placed the origin time at 9:19:26 a.m. Mexico City time and put the hypocenter at 10 kilometers depth in its preliminary report. Those early measurements, issued within minutes of the event, are part of the rapid assessment process that helps civil protection authorities, engineers and state officials decide where to focus inspections first.

The quake came just ahead of Mexico’s national earthquake drill scheduled for Wednesday, May 6. In a country where preparedness is built around frequent alarms, rapid evacuations and repeated drills, Monday’s shaking served as an immediate test of that system, even before inspectors finish tracing the full extent of damage, if any, in southern Oaxaca and beyond.