Tsunami after 'THE BIG ONE' could be even bigger than expected

New research about the possibility of a large tsunami in the Cascadia Subduction zone. I suggest, when you go to the Coast never be more than 15 minutes walk from your vehicle, know how to get to higher ground (above 200 ft) and carry water and power bars, just in case.

YOUTUBE VIDEO 5:49 IN LENGTH

And if you think I'm kidding, perhaps you would like to read about Cannon Beach's Emergency Cache Container Program, in which residents are eligible to participate for an annual fee.

CANNON BEACH EMERGENCY CACHE CONTAINER PROGRAM

Just as a reminder, it's been 322 years since the January 26, 1700 Cascadia Subduction Zone earthquake and tsunami.

LINK

OREGON HAZARDS & PREPAREDNESS - Cascadia Subduction Zone

The Cascadia Subduction Zone is a 600-mile fault that runs from northern California up to British Columbia and is about 70-100 miles off the Pacific coast shoreline. There have been 41 earthquakes in the last 10,000 years within this fault that have occurred as few as 190 years or as much as 1200 years apart. The last earthquake that occurred in this fault was on January 26, 1700, with an estimated 9.0 magnitude. This earthquake caused the coastline to drop several feet and a tsunami to form and crash into the land. What is most surprising is that evidence for this great earthquake also came from Japan. Japanese historic records indicate that a destructive distantly-produced tsunami struck their coast on January 26, 1700. By studying the geological records and the flow of the Pacific Ocean, scientists have been able to link the tsunami in Japan with the great earthquake from the Pacific Northwest. Native American legends also support to the timing of this last event.

 

Oregon has the potential for a 9.0+ magnitude earthquake caused by the Cascadia Subduction Zone and a resulting tsunami of up to 100 feet in height that will impact the coastal area. There is an estimated 2-4 minutes of shaking or rolling that will be felt along the coast line with the strength and intensity decreasing the further inland you are.

 

The Cascadia Subduction Zone has not produced an earthquake since 1700 and is building up pressure where the Juan de Fuca Plate is subsiding underneath the North American plate. Currently, scientists are predicting that there is about a 37 percent chance that a megathrust earthquake of 7.1+ magnitude in this fault zone will occur in the next 50 years. This event will be felt throughout the Pacific Northwest.

 

With the current preparedness levels of Oregon, we can anticipate being without services and assistance for at least 2 weeks, if not longer, when the Cascadia Subduction Zone earthquake occurs. While this will be difficult to overcome, our citizens, businesses, schools, government, and communities as a whole can take steps to get prepared. Take action now by actively planning and preparing yourself and your community to be ready for two weeks for disasters.

LINK TO WEBSITE

10,000 years of Cascadia earthquakes

The chart shows all 40 major earthquakes in the Cascadia Subduction Zone
that geologists estimate have occurred since 9845 B.C. Scientists estimated the
magnitude and timing of each quake by examining soil samples at more than
50 undersea sites between Washington, Oregon and California.

Tremors shove Washington westward, offer clues into next big earthquake - July 21, 2018

Here's an interesting piece from the Seattle Times. 

Tremors shove Washington westward, offer clues into next big earthquake  

Tsunami Forecast Model Animation: Cascadia 1700

Link to YouTube video

Published on Jan 22, 2016

Just before midnight on January 27, 1700 a tsunami struck the coasts of Japan without warning since no one in Japan felt the earthquake that must have caused it. Nearly 300 years later scientists and historians in Japan and the United States solved the mystery of what caused this “orphan tsunami” through careful analysis of historical records in Japan as well as oral histories of Native Americans, sediment deposits, and ghost forests of drowned trees in the Pacific Northwest of North America, a region also known as Cascadia. They learned that this geologically active region, the Cascadia Subduction Zone, not only hosts erupting volcanoes but also produces megathrust earthquakes capable of generating devastating, ocean-crossing tsunamis. By comparing the tree rings of dead trees with those still living they could tell when the last of these great earthquakes struck the region. The trees all died in the winter of 1699-1700 when the coasts of northern California, Oregon, and Washington suddenly dropped 1-2 m (3-6 ft.), flooding them with seawater. That much motion over such a large area requires a very large earthquake to explain it—perhaps as large as 9.2 magnitude, comparable to the Great Alaska Earthquake of 1964. Such an earthquake would have ruptured the earth along the entire length of the 1000 km (600 mi) -long fault of the Cascadia Subduction Zone and severe shaking could have lasted for 5 minutes or longer. Its tsunami would cross the Pacific Ocean and reach Japan in about 9 hours, so the earthquake must have occurred around 9 o’clock at night in Cascadia on January 26, 1700 (05:00 January 27 UTC).

The Pacific Tsunami Warning Center (PTWC) can create an animation of a historical tsunami like this one using the same too that they use for determining tsunami hazard in real time for any tsunami today: the Real-Time Forecasting of Tsunamis (RIFT) forecast model. The RIFT model takes earthquake information as input and calculates how the waves move through the world’s oceans, predicting their speed, wavelength, and amplitude. This animation shows these values through the simulated motion of the waves and as they race around the globe one can also see the distance between successive wave crests (wavelength) as well as their height (half-amplitude) indicated by their color. More importantly, the model also shows what happens when these tsunami waves strike land, the very information that PTWC needs to issue tsunami hazard guidance for impacted coastlines. From the beginning the animation shows all coastlines covered by colored points. These are initially a blue color like the undisturbed ocean to indicate normal sea level, but as the tsunami waves reach them they will change color to represent the height of the waves coming ashore, and often these values are higher than they were in the deeper waters offshore. The color scheme is based on PTWC’s warning criteria, with blue-to-green representing no hazard (less than 30 cm or ~1 ft.), yellow-to-orange indicating low hazard with a stay-off-the-beach recommendation (30 to 100 cm or ~1 to 3 ft.), light red-to-bright red indicating significant hazard requiring evacuation (1 to 3 m or ~3 to 10 ft.), and dark red indicating a severe hazard possibly requiring a second-tier evacuation (greater than 3 m or ~10 ft.).

Toward the end of this simulated 24-hours of activity the wave animation will transition to the “energy map” of a mathematical surface representing the maximum rise in sea-level on the open ocean caused by the tsunami, a pattern that indicates that the kinetic energy of the tsunami was not distributed evenly across the oceans but instead forms a highly directional “beam” such that the tsunami was far more severe in the middle of the “beam” of energy than on its sides. This pattern also generally correlates to the coastal impacts; note how those coastlines directly in the “beam” have a much higher impact than those to either side of it.

The quake-maker you've never heard of: Cascadia

By Michael Martinez, Stephanie Elam, and Rosalina Nieves, CNN

Updated 10:30 AM ET, Sat February 13, 2016 | Video Source: CNN

(CNN)Mother Earth slowly reveals her secrets, and this time, it's a fault line deep in the belly of the planet.

Its name is a whopper: The Cascadia subduction zone.

Its gargantuan size and potential power amaze earthquake experts, who say it could cause the worst natural disaster in the history of North America -- if it ruptures entirely.

This quake-maker sits at the bottom of the Pacific Ocean, where the seabed meets the North American tectonic plate. In all, it stretches 700 miles along the Pacific Northwest, from British Columbia's Vancouver Island to Washington to Oregon to northern California's Cape Mendocino.

Read the entire article

Seaside, OR high school students challenge the community...

SEASIDE — Leaders of Seaside, Oregon High School Associated Student Body are concerned about how unprepared students and the community are for a catastrophic Cascadia Subduction Zone event. They organized "Don't Catch This Wave" to spread awareness about the issue and raise funds to help move the school district's at-risk campuses out of the tsunami inundation zone.

Student boldy leaders seeking new school facilities

SEASIDE — What they don’t know can hurt them. That was the message Seaside High School’s student leaders conveyed to the Seaside City Council last week.

Leaders of the Associated Student Body are concerned about how unprepared students and the community are for a catastrophic Cascadia Subduction Zone event. They organized “Don’t Catch This Wave” to spread awareness about the issue and raise funds to help move the school district’s at-risk campuses out of the tsunami inundation zone.

“We decided we wanted to stand up and work to make a change for ourselves, our peers and the students that sit below us in class and are too young to realize that their lives are in jeopardy every single day when they’re at school,” treasurer Jesse Trott told the City Council.

She and co-presidents Taylor Barnes and Whitney Westerholm shared a version of a presentation the officers prepared for Seaside High School and other schools across the state.

“Our project is all about tsunami preparedness, specifically focusing on the earthquake and tsunami that are supposed to hit our coastline from the very southern tip of Canada to the very northern tip of California,” Trott said.

The hope is to raise funds to relocate Gearhart Elementary School, Seaside High School and Broadway Middle School, which all sit in the inundation zone. Seaside Heights Elementary School also could be remodeled and expanded in the process to house all the elementary students, but nothing is decided.

“Relocating our schools is definitely our top priority,” Westerholm said.

Although it may be lofty, she added, “it’s our goal this year, and even if we don’t reach it, we want to keep this program going.”

A safe place to be

High school students must walk about 1.6 miles to get to an evacuation site and cross bridges in the process. Broadway Middle School students have about 1 mile to walk. Gearhart Elementary students only have a quarter mile, but their route goes west to a site with an elevation of 46 feet at its highest point — likely not high enough.

“What these kids don’t know, and a lot of our high schoolers don’t know, is that they are evacuating to somewhere that isn’t going to keep them safe,” said Westerholm, who has a younger brother at Gearhart Elementary. “That just breaks my heart, to be honest — that we could have had a safe place for these kids to be, and there isn’t.”

When the tsunami will hit is uncertain, but there will be hundreds of students at risk when it does, and that is Westerholm’s main motivation for helping to spearhead the project, she said. Whether it is the current students or possibly their future children, “the fact of the matter is, it will be a group of 400 kids” that are impacted, she added.

The three at-risk schools are not built to withstand an earthquake, which will be the death of many students. For instance, Barnes said, the high school, built in the 1950s, will likely collapse on those who are unable to get out.

“They will essentially be trapped in the school,” he added.

Superintendent Doug Dougherty said the schools do not qualify for any seismic retrofitting money nor can they access those funds to help move the schools because they are in the inundation zone.

The 24-minute presentation is accompanied by a silent video of approximately the same length that shows the high school students walking quickly to their evacuation site “in the best circumstances,” Barnes said.

That means no earthquake damage, no debilitated or injured students, and no devastated bridges. However, according to the students, research shows the community would have only about 15 minutes from the start of an earthquake before a tsunami hits.

“That’s not very much time,” Barnes said.

In the presentation, the students discussed the tsunami that hit Japan in 2011. It is predicted the event on the Pacific Northwest will be similar, Barnes said. The water will move swiftly, faster than a human can outrun, and rise to about 80 to 100 feet in elevation.

Fundraising for relocation

Besides footage and photos from the Japan event, the presentation also included a clip from Oregon Public Broadcasting’s recent documentary, “Unprepared.” In the documentary, Dougherty talked about the 2013 bond measure the school district sponsored to acquire funds to relocate the schools. The price tag was $128 million, and the measure failed. Dougherty has said the district will sponsor a similar bond measure next year.

The students’ fundraising campaign is primarily for contributing to that effort, but they also hope to put some money toward radio communication equipment, natural disaster preparedness kits, pre-assembled food and supply kits, advertising about tsunami evacuation routes and immediate disaster relief.

The student body officers are in the process of sending letters to Fortune 500 companies, politicians and celebrities asking for funds. The main goal, though, is to reach out to other students and schools.

In the past couple of weeks, they gave their “Don’t Catch This Wave” presentation at Gresham and Scappoose high schools. Gresham High School will dedicate its annual Unity Week to raise funds for the Seaside project. Westerholm said they will go back to Gresham in a couple weeks to present during the kick-off assembly for Unity Week.

The Seaside students also are handing out blue ribbons and asking people to tie them in a visible place to show support and bring awareness to the cause. Additionally, they plan to hold a walk-a-thon, similar to Relay For Life, in the spring. Students will find people to sponsor them to run or walk 1.6 miles, the same distance of their evacuation route.

City Councilor Dana Phillips said she was impressed by what the Associated Student Body officers are doing “on behalf of the safety of the students.”

Councilor Jay Barber agreed.

“What we’re seeing here is that our young people really are leading the way for us to wake up to the reality that we live in,” he said.

‘Relocating our schools is definitely our top priority.’

Whitney Westerholm

Associated Student Body co-president