Quake alerts no substitute for resilient buildings, communities: Mexico scientists

Sophie Hares Thomson Reuters Foundation   Expanding Mexico's early warning system and speeding up its alerts could save more lives when earthquakes strike, but making buildings quake-proof and preparing communities better are the best ways to protect people, scientists said on February 6.   Securing enough funds to maintain and run the infrastructure underpinning the SASMEX early warning system is also crucial, said the lead author of a study on its performance, after a chunk of the system was knocked out by a recent storm.   "We're all enamoured by the technology... but we cannot forget the social aspect of early warning systems," said Gerardo Suárez, geophysics professor at the National Autonomous University of Mexico (UNAM).   "There is no alert that substitutes (for) the prudent measures of building properly, having good regulations for construction, and also civil protection," he told the Thomson Reuters Foundation.   In a paper published in the journal Seismological Research Letters, scientists described how the SASMEX system uses algorithms to analyse seismic waves and determine the size of an earthquake.   When an 8.1 magnitude quake hit southern Mexico on Sept. 7, 2017, the system gave the capital nearly two minutes' warning. The earthquake left more than 100 dead and millions in need of aid in the poor states of Oaxaca and Chiapas.   However, on Sept. 19, Mexico City's 21 million people had only a few seconds' notice of a 7.1 magnitude tremor that struck closer in nearby Morelos, killing more than 330 and damaging 11,000 homes in the capital and surrounding states.   New algorithms being developed by the non-profit Seismic Instrumentation and Record Centre (CIRES), which runs the early warning system, would have enabled alerts to be issued up to 10 seconds earlier in that situation, the researchers found.   Expanding the system to areas such as quake-prone Chiapas, Mexico's southernmost state, would also help make communities safer, said Suárez.   QUAKE DRILLS Buildings, including homes, need to be constructed so they can better withstand tremors, with construction adapted to various soil types, particularly in the capital whose soft lake-bed foundation can amplify the impact of quakes, said Suárez.   Also key are civil protection measures including regular drills so people know what to do when an alarm sounds, said Suárez, a technical consultant for the Mexico City government.   Alerts in the capital are broadcast via street sirens, but other places like Oaxaca and Acapulco use radio receivers and television and radio stations to spread SASMEX warnings, which are also sent to schools, the emergency services and local governments.   Built in the years following the devastating 1985 Mexico City earthquake that killed more than 5,000, the early warning system now includes nearly 100 monitoring stations across the most seismically active parts of southern and central Mexico.   Suárez said the recent outage of a SASMEX telecoms tower in Oaxaca after a storm flagged the need to use multiple ways to communicate data gleaned from the system's sensors.   He also pointed to the importance of ensuring CIRES has sufficient funding to keep the network functioning properly.   CIRES said in a statement on its website that a combination of storm damage, a lack of maintenance and funding shortfalls threatened its ability to alert people to quakes.