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What's an earthquake?

An earthquake is the sudden release of stored energy. Most earthquakes occur along a fracture within the earth, called a fault. The shaking caused by this sudden shift is often very small, but occasionally large earthquakes produce very strong ground shaking. It is this strong shaking and its consequences – ground failure, landslides, liquefaction – that damages buildings and structures and upsets the regional economy.

Washington, especially the Puget Sound basin, has a history of frequent earthquakes. More than 1,000 earthquakes occur in the state each year. A dozen or more are strong enough that people feel ground shaking. Occasionally, earthquakes cause damage. The state experienced at least 20 damaging events in the last 125 years.

Be Prepared. Build Kits. Help Each Other. Download our brochure and add the emergency information card, as well. When an earthquake strikes, where will you be? Do you know what to do?

The Nisqually earthquake on February 28, 2001, was a deep, magnitude 6.8 earthquake 10 miles northeast of Olympia. One person died of a heart attack, hundreds were injured, and various estimates place damage at between $500 million and $4 billion. Exact figures are not available, as insurance claims information is not available.

The earthquake threat in Washington is not uniform.

On July 2, 1999, there was a 5.8 earthquake centered in the Satsop area of Grays Harbor County -- although the earthquake was felt a few counties over, most other areas didn't see damage. In Grays Harbor, the damage was estimated at $8.1 million, including repairing and retrofitting its historic courthouse in Montesano.

While most earthquakes occur in Western Washington, some damaging events, such as the 1872 magnitude 6.8 (est.) quake, do occur east of the Cascades. Geologic evidence documents prehistoric magnitude 8 to 9.5 earthquakes along the outer coast, and events of magnitude 7 or greater along shallow crustal faults in the urban areas of Puget Sound.

The Cascadia subduction zone, the fault boundary between the North America plate and the Juan de Fuca plate, lies offshore from northern California to southern British Columbia. The two plates are converging at a rate of about 2 inches per year. In addition, the northward-moving Pacific plate is pushing the Juan de Fuca plate north, causing complex seismic strain to accumulate. The abrupt release of this slowly accumulated strain causes earthquakes.

ShakeAlert Earthquake Early Warning

As of Tuesday, May 4, 2021, the USGS ShakeAlert® Earthquake Early Warning system will send alerts to mobile phones in Washington, letting users know that a nearby earthquake could cause them to feel weak or greater shaking. This alert may provide seconds of warning for people to protect themselves before shaking begins.


Alerts can provide seconds of warning to allow people to take protective action (i.e. Drop, Cover, and Hold On) before shaking begins. The system can also trigger automatic actions like slowing down trains to prevent derailments, opening fire station doors so they don’t jam shut and closing valves to protect water systems.

The system does not predict when or where an earthquake will occur or how long it will last; it detects an earthquake that has already begun, and alerts areas that will experience weak or greater shaking. “Weak shaking” is based on the definition within the Mercalli Intensity Scale and describes the type of damage that might be experienced in that area.You won’t get an alert for every little earthquake out there. For Wireless Emergency Alerts, the system is set for earthquakes 5.0 and above and shaking that would cause dishes and windows to rattle. For the Android built-in system, phones would get an alert for a 4.5 and above. Alerts will not tell you how strong the shaking will be in your area or how much time you have to protect yourself. Research from the USGS estimates that for most earthquakes in the Pacific Northwest, ShakeAlert can provide you with 10 seconds of warning or fewer. Depending on your location, in some cases you may not be alerted before shaking.

It takes several seconds for alerts to be created and delivered to mobile phones, so areas closest to the earthquake epicenter may not receive an alert before the shaking begins. Had the 2001 Nisqually 6.8 earthquake occurred with this technology in place, those in the Seattle area would likely have received a 10-12 seconds notice, according to the Pacific Northwest Seismic Network. However, those in Olympia (which is very close to Nisqually) may not have received an alert at all OR they may have even received the alert AFTER the earthquake had already started.

As soon as you receive an alert, or feel shaking take protective action: Drop, Cover and Hold On.

The majority of earthquake-related injuries are caused by people getting hit by falling objects or falling down while moving during the shaking. Seconds of warning will let people take protective action before shaking begins, reducing the chance of injuries. In most situations, drop, cover and hold on is the recommended way to protect yourself from earthquakes.

Our partners on the West Coast have been working on earthquake early warning for quite some time as the monitoring system continues to be expanded and testing continues. Though the system will be delivering alerts, there remains more work to do. The U.S. Geological Survey and its state and university partners, including the University of Washington, will be adding more seismometers to the network through late 2025 to further enhance the system’s capability. The sensor network is only about 65% complete for Washington state. Additional work with alert distribution partners is needed to improve the delivery speed of alerts to mobile phones for all earthquakes. Algorithms that estimate earthquake size and shaking continue to be tested and improved to ensure the system’s performance in megathrust events (i.e. the “Big One” Cascadia Subduction Zone). With the current ShakeAlert® system, in an M9 Cascadia Subduction Zone earthquake, alerts will be sent but users farthest away from the epicenter may not receive an alert.

The following are ShakeAlert® License to Operate Partners and have products available in Washington state:

Google has notified our agency that when the system goes live on May 4, Android users will have an extra ability to get notifications through their phones without requiring a specific app. Users will receive Earthquake Alerts only if they have their device location setting on and Earthquake Alerts enabled in their location settings. You can learn more about the technology and how the settings work at this website and from this video. Watch Google's April 29 Webinar presentation here

ALERT FM delivers text-based emergency ShakeAlert®-powered alerts to dedicated FM receivers, working when the cell and power networks go out. The system is connected by satellite and delivers messages to residents, schools, hospitals, commercial and industrial facilities within five seconds of activation. ALERT FM is unique as it delivers alerts using the existing nationwide FM broadcasting network. Learn more at Watch ALERT FM's April 29 Webinar presentation here.

SkyAlert offers a business to business service with a receiver device to broadcast audio, turn on emergency lights, open automated doors, turn off natural gas connections and other solutions seconds before an earthquake were to hit. Learn more at Watch SkyAlert's April 29 Webinar presentation here.

Varius provides automated equipment that connects the earthquake early warning alert system to control computers, automated machines and processes. For instance, it can close a gas valve on a boiler or provide elevator overrides, so users aren’t trapped inside. Learn more at Watch Varius's April 29 Webinar presentation here.

Valcom’s system connects to existing legacy page systems and Valcom intercoms, speakers, LED signs and PC screen pops, giving folks critical time to take protective actions. The system also does machine to machine notifications and has the potential to open garage doors, valves and activate emergency lighting systems. Learn more at Watch Valcom's April 29 Webinar presentation here.

RH2: Since 2018, clients have been using RH2’s patent-pending Advanced Seismic Controller to provide a customized and secure connection to the ShakeAlert® signal. Client control systems are automated to take protective actions such as alerting staff, throttling valves and powering down equipment based on the shaking intensity predicted by the Advanced Seismic Controller. Learn more at Watch RH2's April 29 Webinar presentation here.

Learn more about the ShakeAlert EEW system.

Drop, Cover and Hold on

Federal, state and local emergency management experts and other official preparedness organizations all agree that "Drop, Cover and Hold On" is the appropriate action to reduce injury and death during earthquakes.

When an earthquake strikes, where will you be? Do you know what to do? (Check out the link for an infographic).

When an earthquake strikes, most injuries occur from falling or flying objects. The best way to protect yourself is to follow the steps of Drop, Cover, and Hold on! Washington is earthquake country, and shaking can begin at any time – as soon as you feel shaking, or receive a ShakeAlert® earthquake early warning – take action to protect yourself.

Get down on to your hands and knees. This lowers your center of gravity, and makes it much harder for the earthquake shaking to knock you over. It also makes you smaller, so you’re less likely to be hit by falling debris. If you need to move to a safer location, stay low, and crawl on your hands and knees.

Take Cover under something sturdy, like a desk or table if one is available. Cover your head and neck with one hand. If something like a hardcover book is nearby, you can also cover your head and neck with that.

Hold On:
Hold on in that position, and hold on to your cover, so it doesn’t shake away from you. Earthquake shaking may last from seconds, to several minutes for the largest earthquakes. Make sure you’re protecting yourself the whole time!

What you will specifically do depends on where you are and what you’re doing but these general guidelines of Drop, Cover, and Hold on can really help.

Since an earthquake can happen at any time, it’s best to secure your space ahead of time. Think about the places where you spend the most time: Your home? Your workplace? Your bed? Are there any items that could fall during an earthquake, like heavy items on shelves, items in cabinets, or heavy furniture items that could tip over during an earthquake? Taking the time to look around your home now to ensure that these things are safe can help to minimize the personal danger, and economic loss from an earthquake.

To learn how to secure your space and be safer at home, click here.

Check out these 19 simple, easy, do-it-yourself activities to make your space safer before an earthquake.

Preparing for earthquakes also includes personal and family preparedness – being ready for the things that might happen after an earthquake. A large earthquake could cause long-term outages to electricity, and other systems like water and wastewater. In Washington, due to our high earthquake risk, we recommend being 2 Weeks Ready, with food, water, and all the other things you might need to be self-reliant for 2 weeks.

It may sound like a lot of work, but there are simple steps you can take to become more prepared – like Prepare in a Year. And don’t forget to work with your family to build emergency plans.

Be Prepared. Build Kits. Help Each Other. Download our brochure and add the emergency information card, as well.

Also, take the time to learn more about Earthquake Insurance in Washington.

Great Washington ShakeOut

An important part of earthquake safety is planning and practicing. The Great Washington ShakeOut earthquake drill is held each year on the third Thursday of October. It is an excellent opportunity for you, your family, and your organization to practice Drop, Cover, and Hold on, then go over your plans and preparedness for a future earthquake.

All 3,000+ miles of Washington’s Coast are also susceptible to Tsunami hazards, so it is also a perfect opportunity to review your tsunami evacuation plans if you live within a tsunami zone.

To learn more about the Great Washington ShakeOut, and to get information on activities, and other ways to plan a drill in your community, click here.

Seismic Safety in Washington

The Geology Division of the Washington State Department of Natural Resources (DNR) conducts geologic hazards mapping across the state and works to identify our earthquake threats. In addition, the United States Geological Survey works closely with DNR to provide the most accurate, credible, and up-to-date scientific earthquake information to the public and emergency management community. Their work forms the basis for the implementation of seismic provisions and standards in building codes and other infrastructure protection standards. For additional information about the earthquake hazards in Washington, see the links below:

More Preparedness Tips.