Los Angeles Times publicó sobre el sismo M7.2 ocurrido el 18 de abril de 2014. Video muestra acciones preventivas de la población por la activación oportuna de la alerta sísmica mexicana SASMEX

Mexico earthquake: Video captures early-warning alert before shaking

April 18, 2014, 7:56 p.m.
Magnitude 7.2 earthquake shakes Mexico City
la-magnitude-72-quake-shakes-mexico-city-20140418Mexico City had 71 seconds of warning before shaking from a 7.2 earthquake about 200 miles away rumbled into the capital, thanks to central Mexico’s 21-year-old early quake warning system, officials said Friday. It’s a system that California still lacks.

The Mexican warning system could be seen on television (video below), when Televisa news announcer Eduardo Salazar calmly tells viewers that at 9:27 a.m. a seismic alert went off, triggering a shrieking whine on the broadcast. “At this moment, we have felt absolutely nothing,” the anchor says initially.

More than a minute after the first warning, shaking rolls through the television studio in Mexico City, strong enough to knock the news anchor from his stance. His voice strains as the shaking worsens, and he says the studios’s lights are swaying and that some of his staff are preparing to leave. He speaks louder: “It’s a strong earthquake.”

“It did what it was expressly designed to do: warn Mexico City about … earthquakes off the west coast of Mexico,” said Doug Given, geophysicist with the U.S. Geological Survey. The system also gave 27 seconds of warning to Acapulco, about 80 miles away from the epicenter, Given said.

The latest successful test of the region’s Seismic Alert System came as state and federal authorities have struggled to find funding for an early quake warning system for California.

The U.S. Geological Survey needs about $16 million a year to implement a similar system, but the federal government has not supplied funding and a bill passed by the state Legislature and signed by Gov. Jerry Brown last year prohibits state general fund money from being used to develop the system.

Unlike California, Mexico has invested heavily in developing an early earthquake warning system, which alerts the public through air sirens, television broadcasts and even a special earthquake radio system — similar to weather radios in the United States.

Early warning systems have also been developed in Japan and other nations. During the 9.0 earthquake in 2011 in Japan, a television network (see video below) flashed  a quake warning more than a minute before the first shaking was felt at a parliament hearing and about two minutes before violent shaking is felt at the network’s studios.

The early warnings gave news anchors time to cut in before the worst shaking arrived in the capital.

Early alerts give bullet trains time to slow down before shaking starts, limiting the risk of derailment. One Japanese factory has even figured out a way to secure noxious chemicals between the time a quake warning is heard to before the shaking arrives, Given said.

The Mexican system was developed after a devastating 8.0 earthquake struck the country’s west coast in 1985, about 100 miles west of Friday’s earthquake. But Friday’s quake produced only 3% of the energy from the 1985 earthquake, which killed 9,500 people and, in Mexico City, caused the collapse of more than 400 buildings and seriously damaging 3,000 more.

(Friday’s Mexico earthquake terrified residents, but there were no initial reports of serious injuries or major damage in the capital.)

The U.S. Geological Survey has done extensive work on a prototype early earthquake warning system, but it needs to be developed for prime time. More earthquake sensors are needed, as are robust communications systems between the sensors and central computer systems. More testing needs to happen to reduce the chance of a false alarm or a failure of the system, Given said.

The lack of funding has meant that some earthquake-sensing stations aren’t maintained. U.S. Geological Survey seismologist Lucy Jones has said the nearest warning station closest to a 6.8 earthquake off Calfornia’s northern coast on March 9 was out of order when that temblor hit.

California’s restriction on using state general fund money to finance the quake warning system leaves the state’s Office of Emergency Services looking for other sources, both private and public, to cover costs.

After a 5.1 earthquake hit La Habra on March 28, a group of California Congress members – all Democrats — signed a letter asking for federal funding of the system.

«Even a few seconds of warning before the next Big One will allow people to seek cover, automatically slow or stop trains, pause surgeries and more — and the benefits of this small investment now will be paid back many times over after the first damaging quake,» said Rep. Adam B. Schiff (D-Burbank).

Rep. Ken Calvert, a Corona Republican newly appointed to the chairmanship of the Interior subcomittee that oversees the U.S. Geological Survey, said two weeks ago that he would consider the funding if convinced the warning system works.

 video of the Mexican broadcast and a summary of what is said in the warning about the earthquake shaking

It is a Japanese TV network broadcast during the 9.0 earthquake in 2011

Video shows an early quake warning showing up on a computer before shaking arrives in Japan

 Twitter: @ronlin | @hbecerraLATimes

ron.lin@latimes.com hector.becerra@latimes.com

Times staff writer Richard Simon in Washington contributed to this report.

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