Overview
- At 15:05 local time Friday, the quake alarm sounded in parts of southern and eastern Mexico City, prompting precautionary evacuations including at UNAM, but no seismic event was recorded.
- CIRES acknowledged the sound originated from a manual test on SASMEX’s secondary diffusion system via Channel 1 (162.400 MHz) during maintenance, and issued an apology.
- The SSN stated it detected no quake warranting alerting and reiterated that it monitors seismicity but does not operate the alert system; the C5 said its infrastructure did not issue the signal.
- On Thursday, the SSN logged three very shallow events in Naucalpan—magnitudes 2.3, 2.5, and 1.6 at about 1 km depth—felt in nearby CDMX areas with no reported injuries or damage and below alert thresholds.
- UNAM-affiliated teams have installed instruments and are studying a possible 3.4 km local fault in Naucalpan as authorities continue monitoring activity and emphasize preparedness protocols.