Overview
- CIRES reported that the 15:05:32 alert on November 21 was triggered by a manual test on SASMEX’s secondary transmitter (Channel 1, 162.400 MHz) during maintenance, and issued an apology.
- The National Seismological Service (SSN) said it detected no quake warranting a warning and reiterated it does not operate the alert system; Mexico City’s C5 also said its infrastructure did not issue the signal.
- Evacuations were carried out as a precaution in areas such as UNAM campus, Tlalpan and Coyoacán, with no injuries or structural damage reported.
- On November 20, SSN logged three very shallow Naucalpan events—magnitudes 2.3, 2.5 and 1.6 at 16:36, 16:43 and 16:45—felt locally, prompting inspections but yielding no damage.
- SSN data show about 75 small quakes in the State of Mexico over the past year, roughly 34 in Naucalpan, where UNAM-affiliated teams have installed sensors and are studying local faults, including a reported 3.4‑km structure.