The USGS ShakeAlert® Earthquake Early Warning System was made available in Oregon on March 11, a date that coincides with the 10th anniversary of the magnitude 9.1 Great Tohoku, Japan earthquake.
Like Japan, a subduction zone lies off the coast of Oregon, capable of generating M 9.0 earthquakes and a resulting tsunami of up to 100 feet in height that will impact the coastal area. There have been 41 earthquakes in the last 10,000 years along this fault, occurring as few as 190 years or as much as 1200 years apart. The last M 9.0 (estimated) earthquake that occurred in this fault was on January 26, 1700.
ShakeAlert® is the United States’ early warning earthquake alert system, operated by a coordinated coalition of federal state and university partners in Oregon, Washington and California.
It is not an earthquake prediction system, but rather an early warning system that sends an alert to mobile devices and other mobile devices through text-like messages, and through apps as they become available.
These alerts come automatically on most cell phones, making a distinctive sound and displaying a text message that reads, “Earthquake Detected! Drop, Cover, Hold On. Protect Yourself.” This text message is also available in Spanish. Some mobile phones with text-to-voice capability may read out the message text.
“ShakeAlert® can’t detect an earthquake before it occurs, but it can detect an earthquake that has just begun, and it can do so very rapidly,” said Jenny Crayne, OMSI.
When an earthquake happens, the first wave that goes out from the source is the “p-wave,” which does very little to no damage. The second wave that goes out is the “s-wave,” which is slower than the p-wave and produces much more damage.
A network of seismic sensors are located along the west coast, and they continually measure ground motion. One or several sensors will pick up on a nearby quake, and sensors further away will pick up on it later as the p-waves reach them.
“Sensors that are connected to the ShakeAlert® system can detect that initial p-wave, and they send that data to a processing center,” Crayne said.
The processing center calculates the extent of the earthquake, and if an area is expected to experience significant shaking, the information is sent to systems that send out an alert, she explained.
How much warning time a person gets depends on where the earthquake originates and where the person lives. The closer one is to the origin, the less time they have to be alerted. Some may not be alerted at all if they are located at the origin site itself.
However, it should be noted that the most warning a person might get could be up to 60 seconds, or as little as a few seconds. The alert simply gives a person a short amount of time to become aware of what is about to happen, and begin looking for a place of safety.
Other benefits of the ShakeAlert® allow for the automation of control systems, such as shutting off public utilities to save drinking water supplies, slowing a train, sending action warnings across school PA systems, starting back-up generators, and opening first responder and fire station bay doors so they don’t get jammed shut.
“The last 12 months have been extraordinary, especially for us here in Oregon,” said Oregon Office of Emergency Management Director Andrew Phelps.
“One of the biggest takeaways from our experiences with catastrophic floods, battling a global pandemic, historic deadly and devastating wildfires, and the most recent severe winter storm is that there are things we can do as individuals, families and communities to reduce our risk and lessen the impact of these disasters. Avoiding floodwaters, wearing a mask, heeding evacuation warnings, creating defensible space and preparing for the worst make us less vulnerable. So, too, does earthquake early warning.”
No action is needed to receive the alerts other than enabling emergency alerts on your mobile devices. Information on how to do this is listed at the end of this article. There are no tests of the system scheduled at this time, but may occur later this year.
Check that Wireless Emergency Alerts (WEA) are turned on in your mobile device
Mobile phones that have WEAs turned on are able to receive ShakeAlert Messages starting March 11, 2021. While this setting may already be turned on in your settings on your mobile phone, please take the time to check.
Apple iPhones:
- Tap “Settings” > “Notifications”
- Scroll to the bottom of the screen.
- Under “Government Alerts” tap “Emergency Alerts” and “Public Safety Alerts” to turn them on or off.
- If emergency alerts are turned on, the circle will be on the right-hand side of the switch. No further action is needed.
- If emergency alerts are turned off, the circle will be on the left-hand side of the switch. You will need to tap the switch to put it in the “on” position.
Please see a video demonstrating this on an iPhone
Android Phones (the exact location of the options to turn on Emergency Alerts may vary):
- We recommend that you use the search function in “Settings” to find “Emergency Alerts” or “public safety messages.”
- If you can’t find “Emergency Alerts” by searching “settings” it may be within your Messaging app, instead.
- Make sure all alerts are turned on (i.e. “Extreme threats”, “Severe threats”, and “Public safety messages”). If alerts are turned on, the circle will be on the right-hand side of the switch. No further action is needed.
- If alerts are turned off, the circle will be on the left-hand side of the switch. You will need to tap the switch to put it in the “on” position
- Please refer to your mobile phone carrier and/or mobile phone manufacturer’s website for additional information.
- In 2020, Google released an earthquake alert feature that is powered by ShakeAlert. This service is only available on wireless devices using the Android operating system.
Mobile Apps are also available on App Stores: