Earthquake Awareness

Cascadia Subduction Zone

The Cascadia Subduction Zone is an approximately 650 mile long fault stretching from Northern California to Southwestern Canada.  This fault is capable of producing very large (magnitude 8.0 and greater) earthquakes having the potential to cause significant damage to developed areas, tsunamis, landslides, and other detrimental impacts.  

The Cascadia Subduction Zone fault occurs at the intersection of the Juan de Fuca Plate and the North American Plate.  Through tectonic stresses, the Juan de Fuca Plate (oceanic crust) is being subducted beneath the North American Plate (continental crust).  The fault is currently locked by friction, and stress is building along the fault zone.  Rupture of the fault and release of this stress will cause a powerful, damaging earthquake and subsequent tsunami.  Both the earthquake and tsunami will have widespread impacts across the region. 

Recurrence Intervals

Geologic evidence has shown that there have been 40 earthquakes with a magnitude of 8.0 or greater over the last 10,000 years.  The recurrence interval for these earthquakes ranges from about 200 to 600 years with an average recurrence of about 250 to 300 years.  Geologic evidence, along with recorded history of a tsunami reaching Japan, shows the last major Cascadia earthquake event occurred  over 300 years ago on January 26, 1700.  The estimated magnitude of the year 1700 earthquake was 9.0.   

Risk and Impacts

A powerful and damaging earthquake could occur at any time along the Cascadia Subduction Zone fault.  Estimates for the probability of a large earthquake vary, with the currently accepted estimate at about a 30% chance of a magnitude of 8.0 or greater earthquake in the next 50 years.  It is projected that an earthquake of this magnitude would impact over 13 million people from Northern California to Southern British Columbia.  

Large, deep earthquakes, as will be produced from a Cascadia event, result in long duration shaking.  Up to 4 to 6 minutes of ground shaking is expected.  This ground shaking will cause significant damage to infrastructure, including: communications, power, water, sewer, roads, bridges, and buildings.  Brick and mortar structures will incur the most damage.  Poorly compacted fills, along with loose, natural soils will lose strength and behave like a fluid in a process referred to as liquefaction.  Any buildings or other structures supported on soils susceptible to liquefaction will be significantly damaged and may collapse.  Depending on the epicenter of the earthquake, and the location along the coast, 15 to 30 minutes after the earthquake a tsunami will impact the shoreline.  As seen by recent tsunami events triggered by earthquakes in Japan and Chili, a tsunami will be extremely destructive and will cause widespread damage and potentially loss of life in coastal communities.            

Internet Resources

The following links provide additional information on the Cascadia Subduction Zone and the impacts of a large earthquake event. 

Link Description



Great Cascadia Earthquakes – The Risks and Consequences

(video – 21 min)

Oregon Department of Geology and Mineral Industries

Cascadia Subduction Zone – Overview and Impacts on the Northwest

(video – 3 min)

US Army Corps of Engineers

CBS News – The disaster awaiting the Pacific Northwest

(video – 8 min)

CBS News

CNN – The quake-maker you’ve never heard of: Cascadia

(video – 3 min)


Tsunami computer simulation

(video – 8 min)


Cascadia earthquake wave propagation

(video 8 min)

Pacific Northwest Seismic Network

Cascadia Subduction Zone Information

Pacific Northwest Seismic Network

Liquefaction Hazard Maps for Oregon and Washington

Pacific Northwest Seismic Network

Cascadia Information, awareness, and preparedness

Cascadia Region Earthquake Workgroup

While a Cascadia Subduction Zone earthquake will be a major natural disaster, it will be survivable if you are prepared.  It will likely take one or two weeks for first responders to reach many areas so you must be prepared to care for yourself and your family.  The links on this website provide information and resources to help guide in your workplace and personal preparedness.  Don’t be a victim!  Be prepared!


Work Place Preparedness

Earthquakes strike suddenly and without warning. If an organization you lead or work for is located in a region at risk for earthquakes there are many things that can be done to reduce the chances that those who work in or visit the premises will be injured, that property will be damaged, or that your day-to-day operations will be unduly disrupted. These activities all fall under the concept of preparedness, because to be effective, they must be done before earthquakes occur.

Preparing for earthquakes involves (1) learning what leadership and employees should do before, during, and after earthquakes; and (2) preparing now, before a significant earthquake occurs. Workplace preparedness requires the participation of leadership, managers, and workers, as well as those who design, build, regulate, and maintain buildings used as workplaces.

 Workforce Preparation

Every employee, from top managers to part-time and temporary workers, needs to learn WHAT TO DO DURING AN EARTHQUAKE. Safety orientations should emphasize safe places to "drop, cover, and hold on" during earthquake shaking and safe locations where people can rendezvous when the shaking has stopped and it is safe and advisable to evacuate your facilities.

It is recommended that agencies hold periodic, mandatory earthquake drills to give employees opportunities to practice what they have learned and condition themselves to react spontaneously and safely when the first jolt or shaking is felt. To help protect workers in the immediate aftermath of earthquakes or other disasters, arrange for employees to be trained now in first aid, cardiopulmonary resuscitation (CPR), and the use of fire extinguishers. Earthquake training should be thoroughly integrated into the organization’s emergency preparedness, response, and recovery planning.

Internet resources for preparing your workplace are listed below.

Link Description



Organization_Earthquake_Safety Advice

Financial and Banking Information Infrastructure Committee

What to Do Before, During and After an Earthquake – Workplace Focus

Department of Homeland Security

Earthquake Preparedness – Workplace Focus

Occupational Safety and Health Association

Earthquake Preparedness Planning Good Information on Training Employees

City of Seattle

Disaster Preparedness – Workplace Focus

Red Cross

Information on Specific Drills to Prepare the Workforce

Multi-State Partnership in Central U.S

Prepare, Survive, Recover from Earthquake – Great Resources

Earthquake Country Alliance – Public/Private Partnership in California

 Help Your Organization Return to Full Operation Following an Earthquake

 In the days following an earthquake, employees are more likely to be able to come to work and perform effectively if they are less worried about or preoccupied with their families and homes. They should be encouraged to prepare their homes and families in advance for earthquakes and other emergencies (the following section will provide information for personal earthquake preparedness).

Personal Preparedness

It is important to make sure that the entire family is prepared and informed in the event of a disaster or emergency. You may not always be together when these events take place and you should have plans for making sure you are able to contact and find one another.  Following are some links that will help you, your family and neighborhood know what to do during an event and to prepare for a mega earthquake.

Link Description



Earthquake Safety Information and Checklist


Immediate Needs following a mega earthquake


Emergency and Humanitarian Action

(includes a helpful Natural Disaster Pocket Guide)

World Health Organization

(download the PDF “Pocket Guide in Staying Safe in Natural Disasters” at the bottom of this site)

Family Preparedness Made Easy

(5 easy steps)

American Red Cross

Children - get your kids involved


Make a Disaster Plan

American Red Cross

Safe & Well - Register yourself or search for loved ones

American Red Cross

Mobile Applications

American Red Cross


Get Ready to Rumble : A guide to earthquake preparedness

The Seattle Times

How to Prepare for an Earthquake


Emergency Communication Plan for Family Members


Emergency Planning Check list


Emergency Supply Kits


Being Prepared for an Earthquake And Emergency Kits

Center for Disease Control and Prevention

Community Emergency Response Teams (CERT)

(Volunteer Community Certification)


Prepare – A Resource Guide

(Cascade Region)

American Red Cross


National Preparedness Month - September 2017

The Ready Campaign recently released the September 2017 National Preparedness Month (NPM) theme and social media toolkit, which includes graphics, hashtags, and social media content to share.

This year’s theme is “Disasters Don’t Plan Ahead. You Can.” In addition to the overarching theme for the month, each week has a theme highlighting different preparedness actions.

The NPM 2017 Weekly Themes are as follows:

  • Week 1:  September 1-9 - Make a Plan for Yourself, Family and Friends.
  • Week 2:  September 10-16 - Plan to Help Your Neighbor and Community.
  • Week 3:  September 17-23 - Practice and Build Out Your Plan
  • Week 4:  September 24-30 - Get Involved! Be a Part of Something Larger.

For more information, visit