Earthquake Early Warning Tested in San Diego County

San Diego, California - At 11 a.m. Thursday, cellphones across San Diego County started sounding off with a loud tone used for emergency alerts. It was part of a test of the California Earthquake Early Warning System, also known as ShakeAlert.

The test was conducted by the United States Geological Survey, the California Governor’s Office of Emergency Services and the San Diego County Office of Emergency Services to evaluate how quickly the Wireless Emergency Alerts (WEA) system, which sends alerts directly to cellphones in an identified area, can notify the public that shaking is on the way.

For most, it was just a momentary disruption while they checked and silenced the tone. They didn’t need to take any action, but the County asked all San Diegans, whether or not they received the alert, to visit the website before 11 a.m. and note the exact time, down to the second, when the alert was received and to complete a brief survey. For emergency officials, knowing which cellphones did not receive the WEA is just as important as learning how quickly the notification appeared for those who did receive the alert. The survey respondents were rewarded with a coupon for an order of free chips and guacamole donated by Rubio’s Coastal Grill.

The County had directly recruited thousands of  San Diego residents, County employees and County partner agencies like hospitals and local cities, to participate in the survey as well.

Robert DeGroot, ShakeAlert Communications Coordinator with USGS, said the information they gather from the test will be invaluable as they expand the system to other states. The USGS ultimately decides whether to issue a real ShakeAlert based on information transmitted to it from an Alert Center, which would first get data from ground sensors. In San Diego County there are 45 ground sensors that can detect movement and would send the information to the nearest center in Pasadena.

Preliminary survey results will be available when finalized. San Diego County Supervisor Greg Cox, said he looks forward to the ShakeAlert test results.

“We’re hoping that this test which will be the largest test in the state of California, perhaps the country, and the participation of San Diego residents and visitors will help give the scientists and emergency managers the information that they need to develop a system that will work for the entire state of California,” said Cox. “Having a big earthquake here is a realistic possibility that all San Diegans should be prepared for. If we could notify you to duck, to cover, and to hold on before the shaking starts, that could protect a lot of people.”

Ryan Arba, of the California Governor’s Office of Emergency Services, said it would also allow time to stop elevators and stop or slow mass transit to mitigate injuries resulting from an earthquake.

WEA messages, which use geofencing technology to send emergency alerts to people within a specific area, are sent to phones during emergencies such as severe weather or for AMBER Alerts. To try to avoid public alarm, the County and partner agencies sent out regular reminders to the public using social media, community forums and media interviews in the weeks prior.

“The WEA system we are using today is a federal system, and it’s different than AlertSanDiego, our local mass notification system,” said Holly Porter, San Diego County Office of Emergency Services director. “People do not need to register for WEA alerts but they do still need to register their cellphones with AlertSanDiego. These are two separate alert and warning systems that are used by first responders in our community. Ideally, you will get alert and warning on various hazards from different systems. None of them are perfect, so the more systems that we have and the more ways that we have to get protective action recommendations out to the public in an emergency, the better off we’ll be.”

Porter said in an emergency or disaster, people should pay attention to social media, tune in to local media, look at the website to find disaster perimeters and other information. She also urged people who received the alert to consider what preparedness steps they have taken to be ready in the event of a real ShakeAlert.

To register for AlertSanDiego, San Diego’s regional mass notification system, and to learn about earthquake and other disaster preparedness, visit