Seismic early warningLearning from Mexico's earthquake early warning system
In the company of only Japan and Taiwan, Mexico is one of few countries equipped with a seismic warning system that currently broadcasts publicly. Mexico has been broadcasting in a public regional capacity since 1993 via the Mexico Seismic Warning System, which currently has more than 90 sensors in central and southern Mexico. Although no one can reliably predict earthquakes, today’s technology is now advanced enough to rapidly detect seismic waves as an earthquake begins and send alerts to surrounding areas before damaging shaking arrives.
A few weeks after a magnitude-7.1 earthquake struck central Mexico on 19 September 2017 — leaving hundreds dead and dozens of buildings destroyed — USGS seismologist Elizabeth Cochran and a team of experts mobilized to Mexico City to assess the performance of the Mexico Seismic Warning System (Sistema de Alerta Sísmica Mexicano, or SASMEX) and the public’s perception of the alerts.
In the company of only Japan and Taiwan, Mexico is one of few countries equipped with a seismic warning system that currently broadcasts publicly. Mexico has been broadcasting in a public regional capacity since 1993 via the Mexico Seismic Warning System, which currently has more than ninety sensors in central and southern Mexico.
Although no one can reliably predict earthquakes, today’s technology is now advanced enough to rapidly detect seismic waves as an earthquake begins and send alerts to surrounding areas before damaging shaking arrives.
“Mexico is one of just a few number of places around the world that has a warning system and this was also one of the rare times an early warning system had been activated for a significant earthquake,” said Cochran. “We were interested in how people reacted to the alerts and their overall perceptions of the system in the immediate aftermath of this destructive earthquake.”
Discussions the team had included the technical development of the system, and challenges to ensure the alerts have the maximum benefit to the population of Mexico. “We wanted to learn from the experiences of SASMEX in order to apply some of those lessons to the earthquake early warning system we are developing here in the United States,” Cochran said.
The Earthquake Engineering Research Institute selected Cochran to join their reconnaissance team of recognized expert scientists to assess the warning system’s performance. The team also included Dr. Richard Allen (University of California, Berkeley), Dr. Scott Miles (University of Washington), and Diego Otegui (University of Delaware).
Earthquake Aftermath: Recon team studies system performance
USGS says that upon arrival to Mexico City, the EERI team visited the Centro de Instrumentación y Registro Sísmico (CIRES) that operates SASMEX. There, they learned details about how the system performed, including when alerts were issued to Mexico City during the magnitude 7.1 quake. The system issued an alert 3-5 seconds after the initial seismic wave arrivals, which were strongly felt throughout the system.
