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Planet Care

110: Earthquake warning system

Problem:

Although earthquake fault lines are well mapped and the probabilities of earthquakes reasonably well known, people continue to build and to live beside them.

Solution:

Earthquake warning system


On May 22, 1960 the earthquake in Valdivia, Chile was the most powerful earthquake ever recorded. It occurred on a fault that is almost 1,000 mi. (1600 km) long and 150 mi.(24o km) wide, dipping into the earth at a shallow angle.

Various studies have placed it at 9.4–9.6 on the moment magnitude scale. It lasted approximately 10 minutes. Various estimates of the total number of fatalities from the earthquake and tsunamis have been published, ranging between 1,000 and 7,000 killed.

Fifty years later, on 11 March 2011 a magnitude-9.1 earthquake struck 44 mi. (70 km) off Japan, the country’s warning system was little help for people in the path of the torrential tsunami that swamped the coast; nearly 16,000 died.

At a two-day emergency summit at UC Berkeley a month later, an early warning system called ShakeAlert won a US$6.5 million commitment from the Gordon and Betty Moore Foundation in Palo Alto, California, to build a prototype. It had been developed over the years by two seismologists Thomas H. Heaton at the California Institute of Technology (Caltech) in Pasadena, and Richard Allen, at the University of California (UC), Berkeley.

In 1985, Heaton had laid out his idea for a “seismic computerized alert network” in a 1985 paper in Science. But though automated systems could act immediately to prevent chemical spills, electrical fires, and other catastrophes, they would do little to protect San Francisco from an earthquake such as the one in 1906, which was centered near the city.

Over the years, inspired by warning systems in Mexico, Japan, Taiwan, and Chile, among others, which emphasize detecting earthquakes at the source and warning distant cities before the seismic waves arrive, Heaton and Allen collaborated with Japanese seismologists to develop a system they called ShakeAlert. Many people thought such a system would be useless in fault-riddled California, where earthquakes seem to erupt underfoot anywhere, but Heaton and Allen persevered, deploying a pilot system in 2012.

From 2019, with important funding, ShakeAlert covering every corner of Los Angeles, in schools, at businesses, even on smartphone applications is in place. If all goes as planned, this dense network of 1,650 seismometers in California, Oregon, and Washington will detect the first, weak waves of an earthquake and relay a 10-second warning of ground shaking to come. To start, those warnings will go to first responders, power companies, and transit agencies.

But in the next couple of years, alerts could roll out to the public to provide at least a few seconds of warning. Not much time, but enough to take cover. New technologies will sharpen the warnings, too. GPS sensors, though slower than seismometers, can still capture shaking strong enough to outdo conventional instruments, enabling the system to cope better with the biggest earthquakes. Heaton expects artificial intelligence, especially neural networks, will in the next few years be able to discern P waves, an earthquake’s first whisper, from seismic noise earlier than the existing algorithms.

What you can do: Stay alert to earthquake warnings.

Discover solution 111: No longer the moonshot, but the earthshot

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