The Mexico City seismic alert system malfunctioned twice in fewer than 12 hours after an earthquake in Guerrero on Friday night.

The alarm first sounded in the capital just after 9:00 p.m. Friday due to a 5.7-magnitude quake in the southern Pacific coast state.

Despite the temblor, which only caused minor damage, almost 1,000 loudspeakers in different parts of Mexico City played a message that the alarm was sounding as part of an earthquake evacuation drill.

At 8:16 a.m. the next day, some 5,600 speakers emitted the earthquake alarm although there was no seismic activity to trigger it.

The chief of Mexico City’s C5 security command center told the newspaper El Universal that the first malfunction was due to human error.

“It’s clearly attributable to human error. … We identified that [on Friday] and it was corrected,” Juan Manuel García Ortegón said.

The second malfunction occurred because the speakers that emitted the alarm are not connected to the new digital earthquake system, he said.

“In this case, the information we have indicates a system error, a conduct that we hadn’t identified in one of the two systems we have for the activation of the alarm. It’s the oldest one, in fact; we’re finishing the analysis with the technical team but we already have a clear idea of what happened,” García said.

He ruled out any possibility that the alarm was erroneously activated due to a lack of maintenance of the thousands of posts on which the speakers are installed, reiterating that the mistake occurred because not all posts have been incorporated into the new system.

Mexico City Mayor Claudia Sheinbaum said Saturday that she had requested the resignation of two C5 officials with responsibility for the earthquake alarm because two malfunctions in quick succession is a “serious” issue.

“It’s not a minor thing, the earthquake alarm saves lives. It’s not a minor thing that two mistakes have occurred one after the other,” she said.

The erroneous activation of the alarm on Saturday came just over a year after the same thing happened while tests were being carried out to ensure that the alarm’s audio system was functioning correctly.

The sounding of the alarm – which depending on the location of the earthquake can give people up to a minute to flee buildings that could be susceptible to collapse – triggers immediate fear and anxiety in many people who have experienced powerful quakes in the capital such as the magnitude 8.0 temblor on September 19, 1985 and the 7.1-magnitude shock that shook Mexico City and much of central Mexico on the same day 32 years later.

Saturday’s quake was centered in San Luis Acatlán, a municipality in Guerrero’s Costa Chica region about 160 kilometers east of Acapulco, and caused minor damages.

Source: El Universal (sp)