ShakeAlert first came on the scene in 2019. The US Geological Survey (USGS), California Geological Survey, California Governor’s Office of Emergency Services, and several California universities had been working together for over a decade to create an EEW system that could alert people on the west coast to impending earthquakes. When ShakeAlert first launched, it only covered California; two years later, it expanded to include Oregon and then Washington.
The system works by using geographically distributed seismic sensors to detect two types of waves: fast-moving compressional waves and slower-moving shear waves. The sensors send these signals to ShakeAlert’s data processing center. Once the processing center receives signals from four separate sensors, it prompts the USGS to initiate an alert. If the sensors receive stronger signals as the earthquake continues, the USGS will update the quake’s magnitude accordingly. Though ShakeAlert is best known for its mobile notifications, its alerts can also be distributed via radio, television, public siren, and the Federal Emergency Management Agency (FEMA) wireless emergency alert system (most recognizable for its dissemination of amber alerts).
Around the same time that it started serving Oregon and Washington, ShakeAlert sought to enhance its offering by looking at the way people respond to earthquakes on their smartphones. The service partnered with Google. During the partnership’s initial stage, ShakeAlert and Google improved their delivery of earthquake notifications on Android phones. Then they moved on to sourcing data from mid- or post-quake Google searches. The idea is that when several people search for things like “earthquake Los Angeles,” Google can use those search locations to help determine the earthquake’s spread.
— Tim Dawson (@timblor) October 25, 2022
It isn’t clear exactly how much progress ShakeAlert and Google have made on that front, but when a 5.1 M earthquake started in Santa Clara County, California on Tuesday, many smartphone users received notifications on their phones before beginning to feel the ground shake. “Got earthquake early warning in Daly City just before I felt the shaking. Earthquake early warning says it was magnitude 5.1 in Santa Clara County,” tweeted LA Times reporter Ron Lin shortly after the event ended. “Looks like I was 52 miles northwest of the epicenter. I thought the MyShake ShakeAlert warning was a false alarm lol, and then I felt the shaking!” Another Twitter user said they received a ShakeAlert notification seven seconds before they started feeling the quake itself.
Though a seven-second headstart might not sound significant, it can make all the difference to those in an earthquake’s radius. The gap allows people to duck under desks, steer clear of large trees, and otherwise seek cover, hopefully preventing serious injuries. The notifications are also an important facet of infrastructure protection. A well-timed alert can help trains slow down and avoid derailment, close water and gas valves to prevent utility disasters, and even inform firefighters to open firehouse doors before they can jam shut.
ShakeAlert is still under development, meaning not all smartphone users will receive earthquake notifications without taking additional action. Android users appear to be receiving warnings automatically, but ShakeAlert recommends that iPhone users download the MyShake app if they live on the west coast and would like to receive urgent notifications.