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Apr. 07, 2018

California scientists say earthquake early warning system worked in 5.3 tremor


Engineers are Caltech and the USGS are developing Shake Alert, which will provide west coast residents with early warnings for earthquakes.

LOS ANGELES, CA (California Network) - Engineers from Caltech and the U.S. Geological Survey announced that their earthquake early warning system, "shake alert" worked well during yesterday's quake.

The quake was a 5.3 magnitude event and no damage or injuries were reported, aside from a few bricks falling off a chimney on Santa Cruz Island. The quake was centered offshore, about 41 miles away from the coastal city of Ventura and just off the south coast of Santa Cruz Island. The shaking was felt as far north as Bakersfield and San Luis Obispo, and as far south as San Diego. It was also felt in parts of Los Angeles, especially near the coast.

The quake was an event of moderate intensity and had it occurred in Los Angeles, it might have done some light damage or caused injuries. Most So Cal residents would shrug off such a quake, except the region has been in an "earthquake drought," a period of seismic calm. The last similar quake was in 2014. That calm can breed complacency.

USGS and Caltech engineers are working on an early warning system that uses sensors across the state to detect the first waves of an earthquake and send a warning to phones via a special app. Similar systems are already in use in Japan and Mexico. A struggle for funding has resulted in the program taking more than 12 years so far in California. The system is about 50 percent complete, with upgrades due to more than 200 seismic monitoring stations. Funding to complete the project has been allocated in the state budget and the system will be available for the public in about 4-5 years.

In the meantime, the system is being beta-tested and some schools and critical infrastructure may get it much sooner than the general public.

The system works by detecting shaking and by triangulating the origin of the event. It then measures the intensity of the shaking and based on models, anticipates how far away the shaking should be felt. Finally, it generates an alert which sounds on the phones of people with the app installed. Because it is computer-driven, this process can happen almost instantly.

Such a system can provide seconds of valuable warning time, up to a minute-and-a-half in some cases.

At Caltech, engineers announced they had about 10 seconds warning before they felt shaking.

Ten seconds may not seem like a lot of time, but it is enough to stop trains and traffic and to warn people to take cover. Combined with training, such a system can save lives.

Earthquakes always take people by surprise. Shaking is usually gentle at first, then there is a large jolt, and shaking intensifies. The correct response is to take cover at the first sign of shaking, but many people instinctively run outdoors. This can be dangerous because as the shaking intensifies, roofing material, glass, and facades can fall, striking people just as they exit the structure.

An early warning might give some lucky people a chance to get to safety before shaking starts. For those inside, it will give them a few seconds to consider a safe response and to take adequate cover. Instead of crouching under the first desk or chair they find, they may have more time to seek shelter under a sturdier table.

Most quakes last only a matter of seconds, usually about ten to fifteen. However, some can last upwards of a minute or more and those are much more damaging. Quakes can also be frightening because everything moves, even things people would never expect to move, such as sturdy furniture. Everything makes noise and buildings creak. Seconds after the quake begins, shaking can intensify, which can shock people.

It is hoped the system will be functional by 2019 and will begin to protect schools and public infrastructure at that time. It cannot come too soon, for geologists predict the state is overdue for a major quake on the San Andreas fault, although this is an inexact science. A major quake, while likely to occur sooner than later, may not happen for decades or more. But the safe approach is best, and the state is scrambling to deploy its early warning system before nature does her worst. Yesterday's event was just a reminder of what can happen anywhere in the state, at any time.