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).
January 26, 2014 marked the 314-Year Anniversary of the last Cascadia Earthquake
SEATTLE— The last Cascadia Subduction Zone earthquake occurred one hundred years before Lewis and Clark saw the Pacific Ocean. It was a time when native traditions spoke of the ground shaking and the waters rising. There were no bridges to fall and no schools, hospitals and other critical infrastructure in tsunami inundation zones. It was a time when Cascadia was much more resilient than today. “The very advances that are the foundations of our modern communities create vulnerability along with convenience” said Michael Kubler, Cascadia Region Earthquake Workgroup (CREW) President. “The revised Cascadia scenario is a crucial tool for regional leaders to use in developing policies and plans for the next earthquake.”
Events over the last few years have expanded our understanding of earthquake science and the hazards faced by our region from a future Cascadia Subduction Zone earthquake. The Cascadia Subduction Zone extends along the coastlines of northern California, Oregon, Washington, and southern British Columbia. There’s no doubt that Cascadia is capable of producing earthquakes and tsunamis on the same scale as the magnitude 8.8 earthquake off Chile in 2010 and the magnitude 9.0 quake that devastated the east coast of Japan in 2011.
Cascadia’s last great earthquake occurred on January 26, 1700—stresses have been building on the fault ever since. While the full extent of the earthquake hazard was not realized until the 1980s, the Cascadia subduction zone is now one of the most closely studied and monitored regions in the world. “In 2005 CREW first published the Cascadia earthquake scenario, but so much new information has emerged that an update was needed” said Heidi Kandathil, CREW Executive Director. The newly updated Cascadia Scenario joins the list of other free products developed by CREW to help the region’s residents, schools, businesses, planners, and emergency managers prepare for future earthquakes. The Scenario and other materials are available online at http://tinyurl.com/m34v2ex.
A new article in the journal Natural Hazards documents variations in population exposure in coastal communities of Pacific and Grays Harbor counties to Cascadia-related tsunami hazards as a function of modeled pedestrian travel time to safety. Results suggest that successful evacuations may be possible in some communities assuming slow walking speeds, are plausible in others if travel speeds are increased, and are unlikely in another set of communities given the large distances and short time horizon. Communities can use these results to help prioritize tsunami risk-reduction efforts, such as education and training in areas where evacuations are plausible and vertical-evacuation strategies in areas where they currently are not.
More information can be found at http://www.springerlink.com/content/a6177520x5k6080t/ or by emailing the lead author at firstname.lastname@example.org.
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
Oregon Tsunami Clearinghouse (evacuation maps and other resources)
Surviving a Tsunami: Lessons from Chile, Hawaii and Japan (U.S. Geological Survey)
On Oct 20th, 2011 at 10:20 am British Columbians and Oregonians participated in the Great ShakeOut Drill. These drills were aligned with those of California, Idaho, Nevada and Guam, in order to leverage the momentum of partners throughout the Pacific. This initiative will continue to spread earthquake awareness and preparedness information giving us a greater resiliency for when an earthquake hits our region.