Cascadia Subduction Zone report issued for State of Oregon

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Strongsidejedi
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Cascadia Subduction Zone report issued for State of Oregon

http://news.msn.com/science-technology/report-northwest-quake-could-kill-more-than-10000-1

By Lauren Gambino of Associated Press

An earthquake like the one that hit Japan in March 2011 could cause 10,000 deaths and $32 billion in damage in the Pacific Northwest, a new report predicts.

SALEM, OREGON— More than 10,000 people could die when — not if — a monster earthquake and tsunami occur just off the Pacific Northwest coast, researchers told Oregon legislators Thursday.

Coastal towns would be inundated. Schools, buildings and bridges would collapse, and economic damage could hit $32 billion.

These findings were published in a chilling new report by the Oregon Seismic Safety Policy Advisory Commission, a group of more than 150 volunteer experts.

In 2011, the Legislature authorized the study of what would happen if a quake and tsunami such as the one that devastated Japan hit the Pacific Northwest.

...

The Cascadia Subduction Zone, just off the regional coastline, produced a mega-quake in the year 1,700. Seismic experts say another monster quake and tsunami are overdue.

"This earthquake will hit us again," Kent Yu, an engineer and chairman of the commission, told lawmakers. "It's just a matter of how soon."

When it hits, the report says, there will be devastation and death from Northern California to British Columbia.

Many Oregon communities will be left without water, power, heat and telephone service. Gasoline supplies will be disrupted.

...

The 2011 Japan quake and tsunami were a wakeup call for the Pacific Northwest. Governments have been taking a closer look at whether the region is prepared for something similar and discovering it is not.

Oregon legislators requested the study so they could better inform themselves about what needs to be done to prepare and recover from such a giant natural disaster.

The report says that geologically, Oregon and Japan are mirror images. Despite the devastation in Japan, that country was more prepared than Oregon because it had spent billions on technology to reduce the damage, the report says.

Jay Wilson, who works for the Clackamas County emergency management department and is vice chair of the commission, visited Japan and said he was profoundly affected as he walked through villages ravaged by the tsunami.

"It was just as if these communities were ghost towns, and for the most part there was nothing left," he said.

Wilson told legislators that there was a similar event 313 years ago in the Pacific Northwest, and "we're well within the window for it to happen again."

Edited by admin on 11/08/2014 - 06:05
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My comments

My friends who are in the Coastal Northwest (British Columbia, Washington, Oregon, and Northern California).

If you live within the flood plain (i.e. within 100 feet of sea level along a coast line or river front), you need to pay attention to this issue.

During the Great Quake that occurred on 3-11-11 off northwestern Japan, the tsunami reached 30 meters elevation in some areas.  The earthquake lowered the level of land in some port towns and permanently submerged those areas (coastal plains) under the sea's new level.  The tsunami itself swept inland and destroyed entire coastal villages within minutes of the temblor.

The most chilling section of the AP report was this line:

"Sue Graves, a safety coordinator for the Lincoln County School District, told lawmakers that high school students in her district take semester-long classes that teach teens survival techniques in the wake of a giant earthquake. The class teaches students to "duck, cover and hold" when the ground starts shaking, and how to perform CPR."

I hate to be the bearer of bad news, but bureaucrats working in local government are often ill-informed and poorly trained to handle actual real-world disaster situations.

Ms. Graves is either poorly informed and is likely repeating the mantra provided to her by officers and "experts" in other agencies.  If the citizens of the Northwest believe that children are appropriately protected from a 30 meter tsunami by "duck, cover, and hold" drills; then you are sentencing your children to death by tsunami.

The citizens of coastal villages in Japan drill for emergency evacuation to high ground within 5-10 minutes of the siren sounding.

A "duck, cover, and hold" response to a magnitude 7 or 8 temblor on the Cascadia fault line will mean that the children will lose precious few minutes to get to high ground.

If a school is within 100 feet of sea level and in a flood plain, those children will die within 15 minutes of the earthquake hitting.

In my opinion, all schools and school districts in California, Oregon, Washington, British Columbia, Yukon, and Alaska should have mandatory evacuation drills to high ground.  If the school's student body can not reach high ground within 10 minutes of a magnitude six or greater temblor, they will die in the tsunami that will otherwise inundate the entire community.

Evacuation of these stranded high ground survivors will take hours to days, provided that military and civilian transportation exists.  The experience in Japan teaches that the road network will be inoperative because the roads do not exist once the ocean swallows the roadbed.  Even in circumstances where the ocean receded, the road was so covered with debris that the roads were impenetrable by standard autos and trucks.

You can not easily evacuate 1000 high school kids from high ground without using military units (i.e. Chinooks), but the high ground congregation points would need to prepped ahead of time for LZ's.  My guess is that the coastal towns in CA, OR, and WA are not prepped.  These towns are cluttered with pot heads smoking Mendocino Gold and wondering what the big fuss is about.

And, if you're a prepper living within 100 feet of sea level in this zone and along waterfront/riverfront/sea front; you've got a new goal.

My learned advice is to figure on how to get to your children and family within 5 minutes of the quake and then get them out of that area within another 5.

I have personally heard many stories on NHK where prepped guys tried to get their families out.  They went home in their coastal town to get the kid and grandma, but the elderly did not evacuate fast enough and could not move fast enough.  When they took the extra 2-3 minutes to get 80 year old grandma to the Toyota van, the waves over took the family and killed the family (sadly the dad survived the wave while the rest died). 

Do not have this miserable guilt on your mind.

Do not run from this responsibility.  Do not permit the idiotic pot heads to smoke their way to ambivalence.

This is YOUR life, YOUR property, and YOUR future.
 

Read the report!!!!!

  http://www.oregon.gov/OMD/OEM/osspac/docs/Oregon_Resilience_Plan_Final.pdf

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Odds of Cascadia Magnitude 9 quake

The scenario in this report is simply put reflective of the Tohoku 3-11-2011 Great quake.

These calculations look really troubling and show a 1 in 3 chance that we will live to see a Magnitude 8 or greater Cascadia quake in our lifetime.

WOW

____________________________________________

see page 31 of the report

http://www.oregon.gov/OMD/OEM/osspac/docs/Oregon_Resilience_Plan_Final.pdf

Geologists have assembled a ten thousand year record of past Cascadia earthquakes (see Figure 1.3) by

studying sediments in coastal marshes and on the ocean floor. This record shows that past earthquakes

have occurred at highly variable intervals and can range widely in size and in which parts of the Pacific

Northwest they affect. About half of the past earthquakes have been very large (estimated magnitude

8.3 to 8.6) and centered on the southern Oregon coast, while the other half have been great (estimated

magnitude 8.7 to 9.3) and extending from northern California to British Columbia. The most recent

event occurred on January 26, 1700 AD, and was a great earthquake with a magnitude of 9.0. The time

interval between previous earthquakes has varied from a few decades to many centuries, but most of

the past intervals have been shorter than the 313 years since the last event. It is simply not scientifically

feasible to predict, or even estimate, when the next Cascadia earthquake will occur, but the calculated

odds that a Cascadia earthquake will occur in the next 50 years range from 7-15 percent for a great

earthquake affecting the entire Pacific Northwest to about 37 percent for a very large earthquake

affecting southern Oregon and northern California.

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Washington State earthquake presentation

This URL shows the State of Washington maps for any large scale Magnitude 7 temblors along major identified fault lines.

http://www.emd.wa.gov/about/documents/HAZ_RWS_WalshPresentation.pdf

It includes a map of shaking for the Pacific Northwest, including British Columbia, Washington state, and Oregon on the second to last page.

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Is state of Washington really studying the Cascadia threat?

http://www.emd.wa.gov/about/SeismicSafetyCommittee.shtml

I see no discussion or use of predictive models to assess tsunami preparation.

http://www.emd.wa.gov/about/documents/SSC_RWS_Dec_2_Workshop_ReportII_Final_2-24-2012.pdf

This is the URL for the State of Washington's final report.

The report does not appear to consider the same great quake scenario that the State of Oregon considered in its report.  This is a major gap in regional preparedness.

By limiting their discussion to "earthquakes that had been defined for the State of Washington in 2009", it does not appear that the study participants considered the Magnitude 9 Cascadia event that Oregon has elected to use as their new baseline.  By this definition, any residents of the State of Washington will be unprepared for the tsunami event following a 9.0 Cascadia event.

This is the IDENTICAL ERROR to the massive error made by Japanese municipal and regional governments (prefectural governments) made over the last 25 years.  The Japanese seismic community raised at various times the threat of a major Great Quake to coastal Japan.  Some local governments made earthquake preparations, but discounted the idea of a Great Quake, only standardizing to 7-8 point temblors.  This left tsunami barriers 5 meters too short to handle the event.  The barriers would have been fine had the ground not subsided.  But, the ground subsidence sank the level of the ground by 3-5 meters in some areas.

The Oregon study shows that some areas of coastal Oregon and Washington will have an identical event occur.

The tsunami events track back up along rivers and tributaries depending upon local geography and the origin of the temblor.

The absence of tsunami planning for the state of Washington is UNACCEPTABLE!

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San Francisco SPUR URL

This effort was inspired by a similar effort undertaken for the City of San Francisco by the San Francisco Planning and Urban Research Association (SPUR). The final SPUR documents for the Resilient City project in San Francisco can be found at http://www.spur.org/resilient_city. Unlike the SPUR document, the RWS effort will be focused on statewide impacts.

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Cascadia Regional

Cascadia regional earthquake working group honored the 1700 great quake with a press release.

http://www.crew.org/news-events/blog/313-year-anniversary-cascadia-fault-earthquake-tsunami-observed

Vancouver, BC studied this issue 8 years ago!  Their report is here:

http://www.nsemo.org/sites/default/files/files/NSEMO%2520report.pdf

Quoting the Vancouver report for the benefit of Turdites in Vancouver (see page

"The last great earthquake at this plate boundary occurred in AD 1700 (Satake et al., 1996), and although there are no written records of the size or impacts of these waves, their devastating impact on coastal settlements on the outer coast of Vancouver Island is recorded in Native oral histories (McMillan and Hutchinson, 2002). As far as we are aware, however, there are no equivalent oral traditions of tsunamis from this event in the Strait of Georgia.

A computer model2 showing the propagation of tsunami waves from a great earthquake at the Cascadia subduction zone has recently been developed by oceanographers at the Institute of Ocean Sciences in Sidney, British Columbia. The computer model provides a useful surrogate for direct evidence. Their computer simulation forecasts wave heights on the outer (west) coast of southern Vancouver Island and adjacent areas of Washington State, Juan de Fuca Strait, and neighbouring inland waters.

The simulation model predicts that a great earthquake at the plate boundary will generate tsunami waves about 5–10 metres high on the outer coast. These large waves gradually diminish in height as they move through Juan de Fuca Strait and the narrows between the San Juan and Gulf Islands (Fig. 6). The leading edge of the first wave is forecast to reach Vancouver about two hours and thirty minutes after the earthquake. Because Boundary Bay is oriented at right angles to the direction of wave travel, this wave grows to a height of about 1 metre. The second wave, which is approximately the same size as the first, arrives at about three hours and thirty minutes. A third, slightly smaller, wave arrives at about four hours and thirty minutes. By six hours this wave grows to almost two metres in height.

Note, however, that the magnitude of the waves generated by the computer model depends on assumptions about the size of the submarine earthquake and the deformation of the seafloor at the boundary between the two plates. In addition, because of data limitations the model does not estimate the extent and depth of tsunami inundation on land.

If these model predictions are valid, areas of the North Vancouver and West Vancouver foreshores might experience waves one to two metres high about two hours after a great earthquake"

end quote.

The British Columbia government has done computer modeling of hypothetical Cascadia tsunami threats.

http://www.pac.dfo-mpo.gc.ca/science/oceans/tsunamis/modele-tsunami-model-eng.htm

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Cascadia Region Earthquake Workgroup

CREW youtube webcast reviewing Japanese Magnitude 9 Tohoku quake.

Jay Wilson - professional emergency manager gives this talk.

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USGS report on tsunami threat to California

http://pubs.usgs.gov/sir/2012/5222/

Evidence of past events and modeling of potential events suggest that tsunamis are significant threats to low-lying communities on the California coast.

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