Illustration: Sarah Grillo/Axios
When the next "Big One" hits, the U.S. Geological Survey really hopes you'll pay attention to the alert on your phone.
Why it matters: The ShakeAlert system, installed along the West Coast, can provide anywhere from seconds up to a minute of warning to areas outside the epicenter that a big quake is on the way.
- "Depending on the distance, that could be enough time to automatically slow trains, stop industrial machines, start generators, pull a surgical knife away from a patient or tell students to put the 'drop, cover and hold' drill into action," the AP reports.
Between the lines: The system didn't alert anyone this time, and that was on purpose.
- The app "will only send out a ShakeAlert — that is, the message — if a particular area experiences a level of shaking that’s potentially damaging," Robert-Michael de Groot of the USGS told The Verge.
- "This is why we’re saying that it worked exactly as intended because the earthquake was out in Ridgecrest, which is about 150 miles or so from Los Angeles."
- In LA, "ShakeAlerts only get sent to people when there’s potentially damaging shaking — where things get broken or people can get hurt."
- "If people are getting ShakeAlerts every single time there’s an earthquake, people are going to begin to ignore them."
The bottom line: A warning only works if people heed it, and hopefully that moment doesn't come for a very long time.
Go deeper ... In photos: California's historic earthquakes, less than two days apart