Tsunami Awareness & Preparedness in Cascadia Region

CREW is committed to raising awareness of the tsunami risk in the Cascadia region while promoting mitigation and preparedness. Many lessons have been learned from the March 11, 2011 Great East Japanese (Tohoku) earthquake and tsunami – these also apply to the seismically-similar Cascadia Subduction Zone.

The following links provide additional information on ongoing awareness and preparedness activities in the Cascadia region:

Washington State

  • In a Seattle Times, CREW Vice-President John Schelling and CREW Treasurer Tim Walsh express the importance of ongoing awareness activities along with the scientific information needed to better quantify Cascadia’s risk.
  • Washington Emergency Management Division has more information on how to prepare to hazards in Washington state.
  • Project Safe Haven, completed in 2011, developed vertical evacuation options for the counties of Pacific and Grays Harbor.

Oregon

British Columbia

For more information on earthquakes, tsunamis, and how to prepare, please visit our pages on Earthquake Information, Risk Reduction, and read more in our Products and Programs.

If you have any questions, please Contact Us.

March 27th Marks the 50th Anniversary of the Great M9.2 Alaska Earthquake

50th Anniversary of the Great M9.2 Alaska Earthquake of March 27, 1964

March 27, 2014 marks the 50th anniversary of the great Alaska earthquake.   On March 27, 1964 at 5:36 pm local time a magnitude 9.2 earthquake began, ultimately breaking a fault about 400 miles long and a few 100 miles wide, rupturing from beyond the western edge of Kodiak Island to the eastern side of Prince William Sound and from well offshore inland to Upper Cook Inlet. The earthquake lasted approximately 4.5 minutes and is the largest earthquake in U.S. history and the second largest globally, next to the great 1960 M9.5 Chile earthquake.  The earthquake was felt in Dutch Harbor, 800 miles west of Anchorage, and in Seattle 1200 miles to the southeast of Anchorage.  Water well levels rose and fell in 47 states of the U.S.

Picture2Middleton Island, Alaska.  This rock platform was uplifted about 11 feet in tens of seconds by the 1964 Alaska earthquake. White specks are seagulls. Photo was taken near 7-foot tide stage on April 4, 1964. Figure 36, U.S. Geological Survey Professional paper 543-I; Figure 4-A, Circular 491.

As more recent great subduction zone earthquakes have demonstrated, the vast majority of the fatalities were caused by locally generated tsunamis; only 9 of the 129 fatalities attributed to the 1964 Alaska earthquake were caused directly by strong ground shaking. Property losses totaled $2.3 Billion in 2014 dollars.  Key practical scientific lessons were learned from the 1964 Alaska earthquake: 1) widespread liquefaction brought about the development of modern methods for assessing liquefaction hazard, 2) the potential for activation of large-scale secondary faulting became clear, and 3) the first direct evidence for how far-traveled tsunamis are generated led to a basic understanding of tectonic tsunami generation and inundation mapping around the globe.

Picture1The rails near the head of Turnagain Arm outside Anchorage were torn from their ties and buckled during the 1964 earthquake. Figure 24, U.S. Geological Survey Professional paper 541.

In the 50 years since 1964 economies and social structures from widespread States and countries have become much more intertwined, so a repeat of the great 1964 Alaska earthquake will likely have greater impacts on the Pacific Northwest and elsewhere.  The greatest far-flung impacts from the 1964 earthquake along  west coast of North America were due to its tsunami waves. In British Columbia communities along the southwest coast of Vancouver Island were hit hardest, with 21-foot waves damaging and flooding the cities of Alberni and Port Alberni.  Along the Washington coast, 5- to 6-foot tsunami waves struck Ocean City and collapsed the bridge over Copalis River.  Wave heights at Moclips, Sea View, La Push and Wreck Creek reached an estimated 11, 12, 5, 7, and 15 feet, respectively. In Oregon the tsunami took four lives. Seaside, struck by a 10-foot wave, was the hardest hit. Tsunami wave heights reached 10 to 11.5 feet at Depoe Bay, Newport, Florence, Reedsport, Brookings, and 14 feet at Coos Bay. Four people died at Beverly Beach State Park.  California lost 12 people to the tsunami. 10 of these fatalities occurred in inundation-prone Crescent City, which was struck by an unusually large 21-foot wave owing to the shape of the ocean bottom just offshore. Cities all the way to San Diego experienced significant tsunami waves, with one fatality in Los Angeles occurring when the 6-foot tsunami surge struck the Cerritos Channel.

Many institutions are commemorating the 1964 Alaska earthquake by taking stock of preparations and practicing future earthquakes.  The State of Alaska is conducting the Alaska Shield Exercise, which simulates the ground shaking and tsunami effects that occurred during the 1964 earthquake and exercises today’s response plans capabilities.  The Alaska Shield scenario is the centerpiece of the FEMA National Exercise Program Capstone Exercise for 2014, which has participants from across the U.S.

 

For lots more information check out http://earthquake.usgs.gov/earthquakes/events/alaska1964/. Additional information includes 1964 Alaska Earthquake Fact Sheet and a Online Resources Handout

Washington tsunami refuges in National Geographic magazine

The February 2014 issue of National Geographic magazine includes a story about plans to build a tsunami refuge at Ocosta Elementary School in Westport, Washington. The story includes quotes from CREW member John Schelling (State of Washington) and mapped evacuation-modeling results from CREW member Nathan Wood (USGS).

No Miracle that 99.8% of the schoolchildren survived the tsunami

Almost all the elementary and junior high school children of Kamaishi, a small coastal town in Iwate, managed to survive the tsunami.  Many people said it was a miracle, but it wasn’t.  The response capabilities they learned at school helped them to overcome a disaster that exceeded all worst-case scenarios.

See article here: http://wedge.ismedia.jp/articles/-/1334?page=1.

New Japan Tsunami Evacuation Report

Following the tragic 3.11 earthquake and tsunami in Japan, New Zealand’s GNS Science in collaboration with Washington State Emergency Management and other stakeholders set out to further analyze the successes of the evacuation and messaging approaches used in this event. A key element of this research was to investigate both traditional tsunami evacuation strategies used in communities, schools, etc. as well as non-traditional approaches, such as vertical evacuation techniques and draw parallels with the concepts being applied in New Zealand, Washington, and elsewhere in the United States. The report can be found here.

National Tsunami Preparedness Week

National Tsunami Preparedness Week began March 25, and the Federal Emergency Management Agency (FEMA) and Washington Emergency Management Division (WA-EMD) urge all citizens who live along coastlines to take the threat of tsunamis seriously.

In some communities, traditional evacuations are not always an option. FEMA led the development of a new approach to dealing with this challenge called Tsunami Vertical Evacuation. Watch the video on how to use this new approach. This video was developed by FEMA RiskMap, FEMA Region X, WA-EMD, the National Oceanic and Atmospheric Administration (NOAA), and the National Tsunami Hazard Mitigation Program (NTHMP).  Click here for Press Release.

It’s Beach Season in the Northwest: Are You Tsunami Ready?

After months of rain and gray skies, it’s time to pack up swimsuits and sunscreen and head to the Northwest coast. But beach visitors in our region need to prepare for more than sunshine. The Pacific coastline from northern California to British Columbia is at risk from a powerful offshore earthquake and resulting tsunami, events that are likely to cause many injuries, deaths and widespread property damage.

Coastal residents and visitors can reduce their risk from a tsunami simply by knowing when to get out of its path and how to reach safety.

What is the threat?

Tsunamis triggered by nearby earthquakes offshore, as well as distant tsunamis caused by earthquakes across the Pacific Ocean, have struck the Northwest coast. The source of the nearby quakes is the Cascadia subduction zone, which lies offshore from northern California to British Columbia. In this zone, two tectonic plates — the North America plate and the Juan de Fuca plate — come together to form an 800-mile long earthquake fault.

Scientists believe the most recent Cascadia subduction zone earthquake, a magnitude 9 event, occurred in January 1700. The best available evidence indicates that these earthquakes occur, on average, every 500 to 600 years. However, the years between these events have been as few as 100 to 300 years — meaning, all Cascadia residents, especially coastal residents and visitors, should prepare to experience a powerful and potentially damaging subduction zone earthquake in their lifetimes.

After a Cascadia subduction zone earthquake, a tsunami could arrive within 15 to 20 minutes, sending a series of massive waves crashing into the shoreline and flooding entire coastal communities.

How can beachgoers prepare?

Before you head to the coast, find out if your lodging and the places you will visit are in a tsunami evacuation zone. (Oregon and Washington residents can search for an address with this tsunami evacuation zone map viewer.) Once there, look for street signs or seek out evacuation maps that show local tsunami hazard zones and routes. It’s also a good idea to prepare personal disaster supply kits to take with you on any trip.

Signs of a tsunami

You may feel that a tsunami is on its way from the ground shaking that precedes it. Other signs include a sudden rise or fall in sea level or a loud roar like a jet aircraft. Once the shaking stops, move to higher ground or farther inland as quickly as possible. Do not wait for an official warning; a tsunami may arrive within minutes. Wait for emergency officials to issue the “All Clear” signal before returning to low-lying areas. Never try to watch a tsunami or surf a tsunami wave. Tsunamis travel faster than a person can run.

Should Northwest residents be worried about visiting the coast?

Be prepared, not worried. By knowing when and how to respond to a tsunami, residents can significantly reduce the risk to their loved ones and themselves.

More tsunami resources

CREW: Tsunami Mitigation and Preparedness in the Cascadia region

NOAA/National Weather Service Tsunami Ready Program

Oregon Tsunami Clearinghouse (evacuation maps and other resources)

Pacific Tsunami Warning Center

Surviving a Tsunami: Lessons from Chile, Hawaii and Japan (U.S. Geological Survey)

West Coast and Alaska Tsunami Warning Center