Do Mexico City homes need earthquake alarms? One man says yes.

The past two months have brought an unusual succession of earth tremors to the Mexican capital – and a business opportunity for Andres Meira.

Mr. Meira, an architect and social entrepreneur, started a company that produces a small earthquake alert that wails before a potentially destructive earthquake hits the capital.

For sale for about $54, Meira’s device costs a fraction of his competition.

That there is a market at all for such a receiver casts light on a quirk of Mexico’s pioneering seismic alert system, considered one of the most advanced in the world, and the unusual geologic conditions that cause Mexico City to shake even from distant quakes.

The seismic alert system debuted in 1991, and today it has 100 or so sensor stations along the Pacific Coast, where most quakes occur that affect this inland mountain capital.

Because quakes trigger initial compression waves that travel much faster than the shock waves that cause violent movement, the sensors along the coast (180 to 200 miles away) can transmit anywhere from 65 to 80 seconds of warning before the ground begins to shake in the capital. The sensors send signals to radio towers that broadcast the alerts on a special frequency.

City Hall and the federal government have distributed about 100,000 receivers for placement in schools, hospitals, radio stations, subway stations, and other key facilities that blurt out, “Seismic alert! Seismic alert!” whenever a magnitude 6 or greater earthquake is detected. This occurs on average a little more than three times a year. But for average citizens at their home or workplace, there may be no way to know that an alert has sounded. Not all radio and television stations are required by law to broadcast the emergency alerts.

Meira says civil defense officials and politicians have “missed the final step” by creating a system that doesn’t warn the broadest number of people of a pending earthquake. “This is where it all goes wrong.”

Meira, who has an Argentine father and a Colombian mother, is a British-trained architect who worked in Haiti on reconstruction efforts following the devastating 2010 earthquake. After two years there, he followed his girlfriend to Mexico. But he couldn’t shake thinking about earthquakes, partly because the capital sways regularly from tremors.

“The earthquake issue just took over for me. . . . I just got obsessed,” Meira says, noting that he’d been jolted out of bed several times. “In Mexico City, every time there is a temblor, you find all your neighbors in the street in their underwear.”

Endowed with a nerdy streak, Meira consulted with some advisers and found that he could assemble an inexpensive receiver that would pick up the frequencies used to transmit the seismic alerts. He decided to market it under the name Grillo, which means cricket in Spanish.

The receiver is housed in a small square box with a cricket logo stamped on it and an antenna protruding from the top. When it detects a seismic alert, a siren wails and flashing lights go off. It can operate on batteries or from an electric outlet.

The recent debut of the device came at a time when many of the capital’s 20 million or so residents have quakes on their minds.

Residents scurried under tables and ran out of buildings during a magnitude 7.2 quake on Good Friday, April 18, that broke windows and knocked over some trees. Two more quakes, registering 6.4 and 6.1, hit May 8 and 10. A smaller 5.7 quake shook residents out of bed at 3:25 a.m. on May 24.

“Some seismologists are worried about this, thinking it could be a prelude to a larger quake,” says Juan Manuel Espinosa Aranda, director of the Center for Instrumentation and Seismic Registry, which designed and operates the early warning system of sensors.

For many adults, memories remain vivid of a devastating magnitude 8.1 quake in September 1985 that collapsed 371 tall buildings (including 37 public schools), and killed 10,000 people. Another 30,000 people were injured.

Gerardo Lazos, a television producer, was a schoolboy at the time.

“It was hard to stay standing. We all went out to the playground. We tried to keep standing by spreading our legs,” Mr. Lazos recalls.

Mexico City arose atop an Aztec settlement on an island in Lake Texcoco, nestled by volcanoes, at an average elevation of over 7,300 feet above sea level. With the city’s expansion, people built homes on landfills and loose sediment that amplify even distant seismic tremors. The city now sprawls over the dry lake bed.

In the wake of the 1985 tragedy, Mexico built its impressive seismic alert system. Some 100,000 seismic alert receivers have been distributed in the capital and in cities affected by quakes in the Guerrero Gap, the Pacific Coast locale where tectonic plates collide and a major quake is due. Some 50,000 classrooms in greater Mexico City are among facilities with the receivers.

But disaster experts say not enough has been done to ensure that the greatest number of people hear the alerts.

“We’ve got a Formula One racer parked in the driveway. But we don’t have Checo Perez here to drive it,” Espinosa Aranda says, referring to Mexico’s most famous race car driver.

Under Mexican regulations, one private company has the contract to provide the receivers. Its receivers cost an average of $310, pushing them out of the budget for most families. The company does not hold a monopoly, though, and Meira says the Grillo offers a low-cost alternative to the masses.

Several cellphone apps relay seismic alerts, but their alarms are often delayed by up to 30 seconds, wasting valuable time before a quake strikes. A system of 6,000 sirens around the city is said to be in the offing but not yet functional.

Japan, too, has an impressive earthquake early warning system, although Japanese authorities ensure that when tremors trip sensors, warnings go out to factories, schools, television networks, radio stations, and via text message to mobile phones. Nearly everyone learns of the alerts quickly.

“There’s a reason for this. They have the highest seismicity of anywhere on Earth,” says Thomas Heaton, a geophysicist at the California Institute of Technology who is a developer of ShakeAlert, a demonstration early earthquake warning system for the US Pacific Coast.

While early warning alerts can save lives when the ground begins to heave, shake, and lurch, it is only part of the battle. Experts say citizens need to know what to do when they hear an alert, including whether to evacuate buildings.

“Some buildings are built such that they’ll never fall down in an earthquake, and we don’t want those people running out into chaos, or worse, jumping out of buildings,” says John Vidale, director of the Pacific Northwest Seismic Network based at the University of Washington.

Early warning systems are in effect along the Pacific Coast of the United States, both in California and the Pacific Northwest.

But experts say California state legislators have been sluggish in funding enough sensors to provide reliable alerts. Scientists say the Hayward Fault, which runs along the densely populated east side of the San Francisco Bay Area, is due for a major quake.

The clock also may be ticking on a mega-earthquake in the Pacific Northwest, where the Cascadia Fault has been silent for three centuries.

Without better citizen education, alerts potentially could cause chaos, says Arturo Iglesias Mendoza, director of the Institute of Geophysics at the National Autonomous University of Mexico.

“What happens if there is a full soccer stadium, and 5,000 of the 60,000 people receive a quake alert on their phones?” Mr. Iglesias asks. “People should know that the safest thing to do is to stay in the stadium.”

Only a vast program of continuous civic education can teach them that, he added.