More than 1,000 earthquakes occur in Washington 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.
A subduction zone earthquake is different from most earthquakes experienced in this region due to the depth at which it occurs. There is a long history of these earthquakes occurring along the Cascadia Subduction Zone, where the Pacific Ocean meets the West coast of North America, consistently every 200-800 years through paleoseismology. The last Cascadia event has been determined to have occurred January 26, 1700 according to the DNR.
The shaking potential in the city of Bellingham is strong to very-strong on the MMI scale, which measures the intensity of an earthquake in magnitude based on the effects and damage.
In the case of any large magnitude earthquake, there is a likely chance of a tsunami occurring in Bellingham.
Risk
Washington has the second highest risk in the U.S. of these large and damaging earthquakes because of its geologic setting. The number of active faults in Washington state results in over 1000 earthquakes yearly, yet the majority are too low in magnitude to be felt. Large earthquakes are less common but can cause significant damage to the things we count on in everyday life, such as buildings, roads, bridges, dams, and utilities.
Cascadia Subduction Zone Earthquake
The largest active fault that will affect Washington (and the whole Pacific Northwest) is the Cascadia subduction zone. This fault produces some of the largest and most damaging earthquakes in the world (M9). A damaging earthquake is inevitable on this fault, but we do not know exactly when it will happen. It’s estimated that a significant (7.1+ magnitude) Cascadia earthquake has a 37% chance of happening in the next 50 years, and a 10% chance in the next 50 years for a devastating magnitude 9 event similar to what occurred in Japan in 2011. The last earthquake to occur on the Cascadia Subduction fault was in 1700.
After a Cascadia event, areas in Bellingham may be inundated by up to 18 feet of water according to recent models from the Washington Department of Natural Resources. The DNR’s other seismic scenarios also show possible areas affected from earthquake damage.
How to Prepare Before an Earthquake
If you own a home there are ways to reduce damage from an earthquake such as seismically retrofitting the foundation, reinforcing hillsides, and securing chimneys or decks. Consider purchasing earthquake insurance as most homeowner’s policies do not include coverage for earthquake damage.
Sign up to receive SHAKE ALERT notifications which provide valuable warnings seconds before your location experiences shaking from the earthquake.
Pack a bag with essentials which is ready to grab and go after an earthquake. There may not be time to safely gather supplies afterwards. Make sure there is enough for each person to have two-weeks worth of supplies.
Communicate with loved ones on meeting locations and have physical copies of out-of-area contacts information such as phone numbers and addresses. Long-distance calls are more likely to go through when local calls may be not be possible. Sending texts and posting on social media is a more efficient way to communicate when phone lines are congested.
Know any local evacuation routes, particularly tsunami evacuation routes for low-elevation coastal areas. Print out maps to help locate safe locations when cellular data and GPS may not be available.
Secure heavy furniture to walls to and store heavy or hazardous items on lower shelves to reduce falling hazards.
What to do During an Earthquake
Drop
Immediately dropping to the ground prevents you from falling over from the shaking and reduces your chances of being hit by loose objects.
Cover
If indoors, take cover under a sturdy desk, table, or doorway and wait for the shaking to stop. If outdoors, move to a location free of falling hazards and kneel to the ground.
Hold On
If indoors, hold on to a stationary object and wait for the shaking to stop.
If outdoors, hold on to your head and neck with arms and wait for shaking to stop.
If driving, pull over and put the car into drive with emergency brake on.
Accessibility can hinder one’s ability to follow traditional advice so adaptation may be necessary.
Shaking from earthquakes can increase the risk of falling hazards. It is important to stay clear of potential buildings, trees, and powerlines that may fall over. Even small items such as bricks can become dangerous projectiles after an earthquake.
Bellingham has a number of unreinforced masonry buildings which may be dangerous during and after an earthquake. Evacuation is necessary until the structure is deemed safe to enter by authorities.
What to Expect After an Earthquake
Aftershocks are possible for weeks to years after the initial quake. These earthquakes are smaller than the main earthquake, but can still be hazardous, particularly with causing previously damaged buildings to collapse.
Coastal regions are at risk from tsunamis after an earthquake.
Residences and buildings may be damaged and unsafe to stay in. It is crucial to check the immediate area for possible hazards once it is safe to do so.
Transportation may be difficult or impossible as roads can become damaged.
Utilities such as water and natural gas may not be available due to damaged lines.
It is possible that phone lines may be down and communication may be limited. It is essential to have a plan for contacting family members afterward.
Ham radios have proven to be extremely useful when cell service is not available, although HAM radio license and radios must be acquired before an emergency.
Resources
Be Prepared for an Earthquake (FEMA)
What do I do after an earthquake? (USGS)
What emergency supplies do I need after an earthquake? (USGS)
Earthquakes and Faults (Washington State DNR)
Resilient Washington State (Washington State Seismic Safety Committee)
Earthquake Mitigation (Earthquake Country Alliance)
