Remembering the anniversary of the Nisqually Earthquake
By Brian Terbush, WA EMD Earthquake Program Coordinator
At 10:54 a.m., Feb. 28, 2001, the ground in the Puget Sound area began shaking without warning and continued to do so for 30-40 seconds. The Nisqually Earthquake, as it came to be known, was a magnitude 6.8 earthquake originating approximately 30 miles below Olympia in the subducting Juan de Fuca plate and caused upwards of $4 billion in damage, and about 400 injuries in the area. This the most recent damaging earthquake most Washingtonians remember.
With this being the 22nd anniversary of that earthquake, and with the recent tragic earthquakes impacting Turkey and Syria, we want to take some time to reflect on our earthquake hazards here in Washington, and more importantly, what is being done and what still needs to be done to help lessen the impacts of earthquakes. As always, we share this information not to scare you, but to help you understand the known risks and provide you with information about what you can do to help yourself and your family be more prepared for these events when they occur.
As our 2001 Nisqually earthquake (and the very similar deep earthquakes in 1949 and 1965) reminds us, Washington is earthquake country. We live in a seismically-active region where several different types of earthquakes can, and have occurred. In addition to the deep earthquakes that can occur in the subducting plate beneath Western Washington, our state is also crisscrossed with crustal faults close to the surface (such as the Seattle Fault, the Tacoma Fault, the Chelan Fault, the Lake Creek Fault, Saddle Mountain Fault and more), which could cause earthquakes and very intense shaking. Finally, off the coast of Washington is the Cascadia Subduction Zone – a 700-mile long fault capable of producing earthquakes up to Magnitude 9 and tsunamis that will impact the entire coast.
The recent devastating earthquakes in Turkey were an example of crustal faults – earthquakes that occur on faults at or near the surface. Because they are so close to Earth’s surface, these faults can shake the ground around them with a very high intensity. An earthquake’s Magnitude measures how big it is, but intensity measures how strong the shaking is in a particular location.
One way you can think of intensity is by comparing it to a lightbulb: A lightbulb only puts out a certain amount of energy at once (like an earthquake only has one magnitude), but the intensity of that light depends on how close you are to it, and if there’s anything between you and the lightbulb. If you’re really close to a lightbulb, the brightness is going to be much more intense than if you’re far away from it, or if you’re looking through a screen or something. You might even feel heat from the bulb if you’re close enough! Since crustal faults are close to the surface, they’re close. And if you’re nearby, you’re going to experience a lot of shaking.
This can be compared to the Nisqually earthquake, where the ground shook over a wide area, but shaking was less intense than it would be because the fault that broke was 30 miles below the ground. A magnitude 6.8 earthquake like Nisqually is not small, by any means, but being deep below us, the shaking was less intense than it could have been if that same size earthquake occurred right near the surface.
An earthquake on the Cascadia Subduction Zone would be more similar to recent subduction zone earthquakes around the world like the one that occurred in Sumatra in 2004 or in Japan on March 11, 2011. Shaking from a magnitude 9 earthquake on the Cascadia Subduction Zone would also likely last five to six minutes.
Graphic by Washington Department of Natural Resources showing Significant Earthquakes in Washington. While many have occurred in the Puget Sound Region and Western Washington in General, there are still a good number spread all over the state.
With a good understanding of the earthquakes that can happen in the region, thanks to the scientists at the Pacific Northwest Seismic Network (PNSN) and the Washington Geological Survey, it’s important to consider what’s next? Scientists can’t predict exactly when earthquakes will occur, but we do know that they have occurred here in the past and they will occur again in the future. Since we can’t predict the date, or even the date range when the next earthquake will occur here, the best advice we can give is to understand that, and always have an awareness of what to do in an earthquake. It sounds like a lot, but there are some simple steps you can take to make it much easier to deal with.
On this anniversary of the Nisqually Earthquake – if you were there, if you experienced it, what do you wish you had known, or done in order to be more ready for the ground to suddenly start shaking?
To help you get started, we’d like to make sure you’re aware of some of the resources that can help you before, during, and after the next earthquake to be more prepared and more ready next time the ground shakes. Now, while the ground isn’t shaking, is the best time to think about how an earthquake might occur in the future and get prepared for that eventuality. So, what can you do?
First, know what to do when the ground starts shaking wherever you are. In the U.S., that means Drop, Cover and Hold On!
How you Drop, Cover and Hold on depends on where you are, but the basics remain the same. Drop low to the ground as soon as possible to avoid being knocked over, Cover your head and neck and take Cover under a sturdy desk or table if available, and Hold On in that position until the shaking stops. That advice can be applied to a variety of situations as we share in a video here: When an earthquake strikes, will you know what to do? - YouTube. The more quickly you can get into a safe place, the better so practicing Drop, Cover, and Hold On in some of the most common places you might be (e.g., home, work, school, others) is recommended. Less time to get to your safe space means less exposure to the dangers of falling from the shaking or being hit by flying objects (the two leading causes of injury in earthquakes).
Another tool at our disposal in Washington that can help you get to safety quickly and even provide seconds of warning before light or stronger earthquake shaking arrives in your area is the USGS ShakeAlert Earthquake Early Warning System. In Washington, there are three different ways that you could receive this alert: Wireless Emergency Alerts available on all phones, a built-in Alert on Android phones, or by downloading the free MyShake App (strongly recommended for iPhone users). Learn about these three ways and how to get these warnings at https://mil.wa.gov/alerts. Even more importantly, take some time to learn what these alerts will look like and sound like (Android and the MyShake App both have “test” features) so that you can quickly react and protect yourself when you get a warning.
In most cases in Washington, this system will give you 10 seconds or fewer of warning before the shaking arrives. That doesn’t sound like much, but if used wisely, you can be in a safe place when the shaking begins rather than wondering what’s going on. If you experienced the Nisqually earthquake, or another earthquake, wouldn’t you have preferred a few seconds of notice before the ground began shaking?
In addition to knowing and practicing what to do when the ground shakes, you can also make sure that the spaces you spend your time at are safer before the ground starts shaking. Installing cabinet latches, securing shelves, pictures and other items to the walls and moving heavy things to lower areas in your home so they won’t fall during earthquake shaking can all make your home or office much safer. Think about doing a “Home Hazard Hunt,” where you walk around and identify things that could be dangerous during an earthquake and take some steps to secure your space.
One item that may be beyond our personal control but needs attention in Washington is making our most vulnerable buildings safer. While building codes in Washington mean buildings are unlikely to collapse, there are still a large number of buildings of more dangerous construction that can be a huge hazard during even smaller earthquakes. Damage to these Unreinforced Masonry buildings – brick buildings without any additional steel reinforcement – was one of the most common types of building damage during the Nisqually Earthquake. Without fixing them, it will be again in our next quake.
Reinforcing Masonry buildings can be costly, but it can also make a huge difference during and after an earthquake. It can save lives by preventing bricks and materials from raining down into the street or into buildings, and making buildings less likely to collapse. In addition, keeping the buildings standing is critical for ensuring that people have places to shelter after an earthquake, and preventing damage to the businesses and living spaces within. Unreinforced Masonry buildings in Washington also include a number of government buildings and schools, and many historic buildings important to their communities. Fixing these buildings so they’re more able to withstand the next earthquake will have long-lasting impacts on the communities they are a part of.
As we think back to the February 2001 Nisqually earthquake, and with our thoughts going to all those impacted by the recent earthquakes in Turkey and Syria, it’s critical to think about what can be done to mitigate the impacts of these natural hazards. It’s not a question of if, but when another earthquake will occur here. Still, that doesn’t mean we’re powerless in the face of these Earth-shaking forces.
Take steps now to ensure you and your family are safe the next time the ground shakes in Washington.
- Learn how to Drop, Cover and Hold On, and practice how to do it in a variety of situations so you can act quickly.
- Ensure that you have ShakeAlert earthquake early warning enabled on your phone and learn what the alerts will look and sound like so you can use them to act quickly.
- Look around your home, school, office, or other areas where you spend time, and take steps to secure your space.
- Work with your local community to promote retrofitting unreinforced masonry buildings in your community so they’ll be safer when the ground shakes, saving lives and property, and reducing the amount of time it takes to recover after a quake.