There is now a possibility of 100-foot tsunami surges along the NW coast.

Emergency planners in the Northwest are unsure whether a similar earthquake here would cause a tsunami to be far larger than expected in light of last year's megaquake and tsunami in Japan.
NOAA
A computer simulation displays the path taken by a tsunami produced by an earthquake of magnitude 9 off the Northwest Coast. Scientists are trying to determine whether the large waves produced by the earthquake in Japan last year means a similar earthquake here could produce larger-than-expected tsunamis. Wave sizes are indicated by darker hues.

​The boundary where the Juan de Fuca plate subducts beneath the North American plate is known as the Cascadia subduction zone. A tsunami far larger than initially anticipated may be caused by an earthquake along this zone, according to some experts and emergency planners in the wake of last year's megaquake in Japan.

The worst-case scenario that emergency managers in Washington and Oregon could envision was the possibility of 30-foot waves crashing into the Northwest coast. A year after the megaquake and tsunami that hit Japan, people are now debating if their dreams were truly horrific enough.

In light of the enormous walls of water that took over 20,000 people to their deaths on the day the Japanese simply call 3-11, scientists and planners are reevaluating the region's tsunami risk. Everyone was caught off guard when the tsunami, which in some locations reached 130 feet high.

Extreme levels are unlikely to occur in the Pacific Northwest, but geologists warn that the next time the offshore Cascadia subduction zone fault bursts, some areas of our coast may be pummeled by waves up to 100 feet high.

Vasily Titov, head of tsunami modeling at the National Oceanic and Atmospheric Administration in Seattle, said: "Underestimating kills people, so it is clearly something we need to be ready for. and the incident in Japan vividly illustrated that.

The Obama administration is proposing to remove $4.6 million from NOAA's tsunami projects as part of a campaign to decrease government expenditure and the deficit, while researchers are still sorting through the catastrophe and learning its lessons.

State officials worry that the budget cuts may compromise the security of coastal towns.

According to John Schelling, the earthquake and tsunami program manager for Washington's Emergency Management Division, "there will be major ramifications for our continued ability to sustain the degree of preparation on the coast today."

According to NOAA officials, the funding for state programs like tsunami education and evacuation signs will be most significantly impacted by the reduction, while the federal tsunami detection and warning system will remain unaffected.

In response to the 2004 Indian Ocean tsunami, which claimed more than 230,000 lives, the federal government increased financing for tsunami initiatives. Since then, scientists have enhanced computer simulations of how tsunamis spread.

Results were utilized by states to map hazard zones for numerous coastal municipalities in Alaska, Washington, Oregon, and Northern California. Typical Pacific Northwest scenarios result in maximum wave heights of around 30 feet.

similar event

What shocked scientists in Japan was how far the plates slipped past each other during the earthquake: more than 160 feet in some spots, roughly half the length of a football field. The earthquake and tsunami that struck Japan originated on a fault similar to the Cascadia subduction zone, the boundary where the geologic plate that makes up the ocean floor is forced under the continent.

Titov said, "That's enormous. That much slide was unimaginable before."

A tsunami is started when underwater plates shift and push the water column upward.

Whether the Cascadia subduction zone might be capable of more slip than the 65 feet factored in to most tsunami models is the question that scientists are currently attempting to address.

According to Tim Walsh, geologic hazards chief for the Washington State Department of Natural Resources, "obviously, greater slide would generate a bigger tsunami" (DNR).

There may be less chance of such a massive fall here due to differences between Cascadia and Japan. The magnitude 9 earthquake in Japan concentrated a lot of energy into a small fault segment, which may help to explain why the plates moved so much.

A similar-sized earthquake in the Northwest would likely have a force that was distributed over the full 700-mile length of the subduction zone, which should lead to less slide overall. In addition, Cascadia lacks the deep undersea trench that Harry Yeh, an Oregon State University tsunami expert, believes may have exacerbated seafloor displacements in Japan.

But the Japanese disaster, according to Yeh, who is currently in Japan to investigate the 2011 tsunami, revealed that a lot of what experts believed they knew about subduction zones was incorrect.

We have discovered that we do not truly comprehend this Earth, he continued.

Seismologists in Japan drastically overestimated the size of an earthquake that may be produced by their subduction zone. Based on the geologic records of more than 20 massive earthquakes over the previous 10,000 years, planners in the Northwest have already built a worst-case scenario of magnitude 9 into their plans.

The most recent one, which occurred in 1700, is rated a 9 because the tsunami it caused was so strong that it inundated communities in Japan. However, there is proof that some of the earlier Cascadia earthquakes and tsunamis did occur.

new plans for evacuation

Stéphan Grilli, an oceanographer at the University of Rhode Island, was one of the first scientists to predict 100-foot waves from a magnitude 9.2 Cascadia earthquake. He claimed that the events in Japan support his past research.

People are starting to understand how these massive subduction zones can produce tsunamis that are considerably larger than anyone had predicted, according to Grilli.

Officials in Grays Harbor County, which contains Ocean Shores and other coastal villages, revised their evacuation preparations after witnessing seas engulf ostensibly safe regions in Japan. According to Chuck Wallace, deputy director for disaster management, assembly points were moved to higher altitudes and away from potential landslides.

To know if what we've been modeling for is sufficient is what's most important to him right now, he said.

The San Juan Islands and the Strait of Juan de Fuca will be included to the state's tsunami hazard maps, according to Walsh of the Washington DNR. Puget Sound shouldn't experience significant flooding as a result of a coastal tsunami. However, a seismic event along the Seattle Fault, which passes through the city and out to sea on the Eastside, might trigger underwater landslides and generate small tsunamis.

Walsh wants to simulate a Lake Washington scenario, but like the other map updates, that work may be halted by NOAA's suggested budget cuts.

Additionally, the changes would stop financing for tsunami evacuation signs, which are a favorite target for thieves, and for testing and maintaining tsunami warning sirens. Federal funding for community workshops, exercises for evacuations, and initiatives to educate hotel and business owners along the shore are all at risk.

Over the past few years, states have received more than $40 million from NOAA to increase education, outreach, and readiness, but the agency never meant to continue funding the initiatives indefinitely, according to Jane Hollingsworth, the tsunami program manager.

Wallace, a one-man operation, argued that local governments can't afford to take up the slack.

These jurisdictions are currently "bare bones," he declared.

the primary priority for NOAA

A network of 40 tsunami detection buoys and the tsunami warning centers in Alaska and Hawaii are NOAA's main priorities due to its own limited funding, according to Hollingsworth. The system has sufficient redundancy that cutting $1 million from buoy maintenance won't affect performance, she noted.

Initially, seismic signals are used to generate tsunami warnings. The buoys provide more information on the size, direction, and duration of tsunamis.

While the buoys are helpful for tsunamis caused by far-off earthquakes, Schelling claimed that when the Cascadia fault slips, they won't be much help for the Northwest coast. In many locations, waves will arrive in less than 30 minutes, giving little time for official warnings. In order to produce a thorough forecast more rapidly, NOAA might relocate some buoys closer to the fault. However, residents of coastal areas must be trained to flee to higher ground as soon as the earth stops trembling, which is why he believes that public education is so important.

The only thing that will save lives, according to him, is having a people that is trained and prepared.

Despite the shocking death toll in Japan, 90% of those in the flooding zones made it to safety because they knew what to do, according to Jody Bourgeois, a tsunami expert at the University of Washington.

She believes the survival rate wouldn't be nearly as high in the Northwest, where being prepared is not ingrained.