ShakeAlert Rolling Out in Washington on May 4

ShakeAlert Rolling Out in Washington on May 4

April 30, 2021

by Gabriel Lotto

The West Coast’s earthquake early warning system will deliver alerts publicly through the Wireless Emergency Alert system and Android OS.


Starting on Tuesday, May 4, people in Washington will have another line of defense to protect their families in the case of a damaging earthquake. ShakeAlert®, the earthquake early warning system for the West Coast of the U.S., will be able to send earthquake alerts to mobile devices in Washington.

There will be two ways for ordinary people to get notified of an earthquake that has begun underfoot:


  1. Wireless Emergency Alert (WEA) messages, which will look similar to AMBER Alerts. For people expected to feel shaking, WEA will push notifications to phones for earthquakes greater than magnitude 5.
  2. Built-in alerts on Android mobile devices. Android users who are expected to feel shaking will receive alerts for earthquakes greater than magnitude 4.5.

At this time, there are no downloadable mobile apps in Washington powered by ShakeAlert.


Together, WEA alerts and built-in Android alerts will be able to reach the majority of Washington residents should a major quake strike our state, with no downloads required. Go to to learn how to ensure that your alerts are turned on (by default, earthquake alerts should be enabled).


To learn more about ShakeAlert and speak to PNSN earthquake scientists, join us for our ShakeAlert Rollout Facebook Live event, May 4th at 6:30pm.

How much warning does ShakeAlert provide?

In most cases, ShakeAlert can provide seconds to tens of seconds of advanced warning before shaking starts. The farther you are from the earthquake’s epicenter, the more time you have to respond. For most earthquakes, there is a “late alert” zone, right above the fault, in which you will feel shaking at the same time as our seismic instruments do, meaning you likely will get an alert after shaking has begun.

What can you do with just seconds of warning? Quite a lot, if you’re prepared. Even seconds of warning is enough time to take action and make decisions before strong shaking arrives. If possible, Drop, Cover and Hold On - protect your head and neck and brace yourself beneath a sturdy table.

Some businesses across Washington are also using warnings from ShakeAlert to take automatic protective actions to be more earthquake resilient, like throttling water utility valves to prevent emptying of reservoirs or delivering messages over the PA system at schools.

In more detail...

Most of us in Washington know about The Big One, a massive earthquake along the 700-mile Cascadia Subduction Zone that stretches from Northern California to Canada’s Vancouver Island. Earthquakes like this are the biggest threat facing our coast, but they are thankfully rare. More common are shallow crustal earthquakes and deeper intraslab events. Here is a bit more information about what to expect for each of these types of quakes.


  • Shallow, crustal earthquakes. Events like these can occur throughout Washington. The 1872 Northern Cascades earthquake is a fairly recent example. The Seattle Fault that passes under the Puget Sound region has also hosted damaging quakes in the more distant past. For shallow earthquakes you should expect fewer than 10 seconds of warning from ShakeAlert.
  • Deeper, intraslab earthquakes. Earthquakes like these are the most common in western Washington. Remember the 2001 M6.8 Nisqually earthquake? Earthquakes like these happen every few decades and can cause a great deal of damage. Similar to shallow quakes, ShakeAlert may provide up to 10 seconds of warning for deeper events.
  • Massive subduction zone earthquakes. Earthquakes on the Cascadia Subduction Zone can begin anywhere between California and Canada. If the next big one begins in Southern Oregon, people in Washington could get 50-80 seconds of advanced warning. But if the rupture starts off the coast near where you live, you may only get a few seconds of advanced notice from ShakeAlert.

What is the science behind ShakeAlert?

ShakeAlert cannot predict earthquakes (and neither can scientists or gurus on Youtube), but it can rapidly detect earthquakes soon after they begin, relaying information to people before shaking arrives at their location. 

Over 230 stations contribute to the ShakeAlert network in Washington, with more coming online every week. Image credit: Rebecca Gourley, UW News.

Over 230 stations contribute to the ShakeAlert network in Washington, with more coming online every week. Image credit: Rebecca Gourley, UW News.

PNSN’s network of seismic sensors throughout Washington State constantly monitors the ground for motion. Earthquakes can start just about anywhere, but we place our stations where the risk is highest, taking into account both the background level of earthquake hazard and the locations where the highest population is exposed. When four or more stations begin to feel shaking, ShakeAlert algorithms determine the location and magnitude of the quake, pushing out a secure data signal called a ShakeAlert Message. 


Next, delivery partners licensed by the U.S. Geological Survey put that data into action, delivering notifications on phones, playing automated messages on public address systems at schools, securing infrastructure systems, and more.


Click here to read more about how ShakeAlert works and how to protect yourself.