U.S. Geological Survey’s Earthquake Early Warning System, California

Tom Heaton thought it was crazy when, back in the 1970s, he first heard about the concept of an earthquake early warning system.

Japan’s high-speed rail system already was using the technology to slow down trains before shaking from a distant earthquake hit. But the more the young Caltech scientist did his calculations, the more he dreamed of bringing the system to California.

By 1985, he proposed what still was considered radical, a “seismic computerized alert network” for the state. Over the next decade, major earthquakes in Northern California and the San Fernando Valley added urgency to the effort.

On Thursday, Heaton was at Los Angeles City Hall to watch a demonstration of the warning system that culminated his life’s work — sirens and audible announcements aimed to air before the shaking arrives, declaring, “Earthquake! Earthquake! Drop. Cover. Hold on. Protect yourself now!”

Within months, Los Angeles Mayor Eric Garcetti said, some residents could begin to have access to a network on their smartphones that would offer crucial seconds of warning before shaking from a major quake strikes.

It’s been a long time coming, for me personally. I mean, I got excited about this in 1979. And that was a long time ago.

-Tom Heaton

about the U.S. Geological Survey’s earthquake early warning system

LATimes.com, October 18, 2018 - New seismic era begins as earthquake warnings are readied to ring in California.

An earthquake warning system is a system of accelerometers, seismometers, communication, computers, and alarms that is devised for regional notification of a substantial earthquake while it is in progress.

Wikipedia

Earthquakes radiate outwards from the epicenter. As mobile communication has gotten smaller this network of sensors, computers, and measuring devices have been utilized to trigger alarms. Because wireless communication is faster than the s-wave propagating through the ground you get seconds of warning before it reaches you. The further away you are the more time you get. And when The Big One hits that will be vital.

This is really good news! The article goes into some of the political drama surrounding this idea but I just like it when somebody gets a good idea and they see it through to the end! The guy is nearing retirement for crying out loud! Way to go!

How does Earthquake Early Warning Work?

The objective of earthquake early warning is to rapidly detect the initiation of an earthquake, estimate the level of ground shaking to be expected, and issue a warning before significant ground shaking starts. This can be done by detecting the first energy to radiate from an earthquake, the P-wave energy, which rarely causes damage. Using P-wave information, we first estimate the location and the magnitude of the earthquake. We use this to estimate the anticipated ground shaking across the region to be affected. The method can provide warning before the S-wave, which brings the strong shaking that usually causes most of the damage, arrives.

California Integrated Seismic Network - CISN.org

That is what is happening (because I did not explain in OP and found a way better explanation over there at cisn.org)

loll early warning is one … to give the call for evacuation is an second ! who would burn his hand to order evacuation?
remember the italian geologes.... who were prosecuted for an call...
moral : money wins howmany lives it will take !

Here's some snippets from the news being shared in the Pac NW about it:

The system being built for California, Oregon and Washington detects that an earthquake is occurring, quickly analyzes the data and sends out alerts that may give warnings of several seconds to a minute before strong shaking arrives at locations away from the epicenter.

It's a start. I'm happy for that. There's a certain amount of time people have to act, depending on location(ie near tsunami zones, etc) once a warning is given.

"The system is not yet finished, it's not complete, there is a lot of work to be done, however there is a lot of capability in the system as it exists today to the point it can definitely be used," Given said.

The sensor network is about 50 percent complete and funding has been secured to complete it in California in the next two years and get two-thirds of the way built out in the Pacific Northwest, he said.

Operational but not yet complete.

Officials now want to open ShakeAlert to a wide array of applications and are encouraging potential users to contact the USGS.

Source
USGS encourages contact from people to give comments or advice on the app and such.

It doesn't however include a mass notification system such as due to cellphone technology's delays in delivery.

From the official USGS site:

Broader public alerting at the magnitude 5.0 level will begin when existing mass alerting technologies are able to deliver alerts at the speed or scale needed for effective earthquake early warning. The ShakeAlert partners are working with both public and private mass alert system operators including FEMA, cellular carriers, mass notification companies, and others to provide that functionality. Finally, the public has not yet been educated about the system and how to respond to alerts when they are delivered.

Shakealert.org