Overview
- Mexico’s seismic service recorded the quake at 00:42 local time near San Marcos, Guerrero, revising the magnitude from 5.2 to 5.3 and then to 5.0.
- The SASMEX warning sounded in seven cities, including Mexico City, with estimated lead times ranging from about 8 to 61 seconds.
- Authorities activated emergency protocols in the capital with helicopter overflights and infrastructure checks, and reported no casualties or structural damage.
- The event is part of an ongoing aftershock sequence from the January 2 mainshock, with 4,657 replicas logged by early January 16.
- Mexico City’s C5 reported 98.1% effectiveness of its loudspeaker network, and the president requested a review of the mobile alert wording following public reaction.