Earthquake Practise - What will you do if Oregon has a big earthquake?
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January 24 2022
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Earthquake Practise

What will you do if Oregon has a big earthquake?


Story by The Oregon Herald Staff
Published on September 22, 2021 5:33 AM
 
5,925 participants are registered in the 2021 Great Oregon ShakeOut in Lincoln (as of 08/18/2021 2:40 AM PST The Great Oregon ShakeOut is an annual opportunity to practice how to be safer during big earthquakes: “Drop, Cover and Hold On.
 
PORTLAND, OREGON - Lincoln County Emergency Management is encouraging community members, businesses, and community groups to participate in the 2021 Great Oregon ShakeOut. This event provides a chance for you to practice what you would do during an earthquake -wherever you may be at that time. While the official event takes place on Thursday, October 21, 2021 at 10:21 am, you can practice your drop, cover, and hold during the days leading up to or directly after the drill. The important part is to register if you participate.

By registering you will assist Lincoln County Public Safety agencies document the high level of preparedness in our community. Participation in this event shows that we are working together to strengthen our community resiliency and emergency preparedness. This event is also provides a good reminder to update your emergency plans and supplies.

Below is a graphic on the annual summary of participants here in Lincoln County.

Oregon ShakeOut Statistics - www.shakeout.org/statistics/ 

Lincoln County residents live on the Cascadia Subduction Zone Earthquake Faultline. This means it is even more important for our communities to be informed and prepared. Keep an eye out for our new information and resource series, Cascadia: the Basics, coming this fall. 

More information on earthquake and tsunami preparedness:

Great Oregon ShakeOut

Lincoln County Emergency Management 

CDC

Ready.gov

Red Cross

 

Respectfully submitted, 

 

Virginia "Jenny" Demaris
Emergency Manager
Lincoln County Sheriff's Office - Emergency Management
225 W. Olive St., Newport, Oregon 97365
is@co.lincoln.or.us">vdemaris@co.lincoln.or.us , (541) 265-4199 Office

1873 OREGON EARTHQUAKE

This is not a photo of the 1873 earthquake but image what a big earthquake could do to the city of Portland.
Review of 1873 quake shows it was largest in state history Source
PORTLAND – A major earthquake that struck Oregon more than a century ago, rattling towns from the Seattle area to San Francisco, may have been the strongest in state history, according to a re-analysis of historical records.

The new study indicates the quake centered near Brookings on Nov. 23, 1873, reached magnitude 7.3, much stronger than the 6.7 originally recorded.

In comparison, the Nisqually quake near Seattle in February 2001 reached magnitude 6.8, causing about $2 billion in damage.

But both quakes were "intraplate" earthquakes, which occur beneath one of the many sections of the Earth's crust called tectonic plates.

In the Northwest, such quakes happen in the Cascadia subduction zone, the area where the plate lying under the Pacific Ocean slides eastward beneath the plate that holds most of North America. The lower plate breaks apart as it's slowly recycled into the planet's interior. Intraplate earthquakes strike the Puget Sound as often as every decade or more and commonly have few aftershocks.

But they are unusual in Western Oregon, and scientists are unsure why. None have been recorded in most of Oregon and southern Washington, so there are few clues.

The 1873 Brookings quake "was possibly the last shred of evidence we had of that kind of earthquake in Western Oregon," said Ivan Wong, a seismologist at URS Corp., a California engineering company.

He discussed the re-analysis of the quake at a meeting of the Geological Society of America in Corvallis earlier this month.

The new look at the historic Brookings earthquake began when William Bakun of the U.S. Geological Survey in Menlo Park, Calif., re-examined the earthquake record of Northern California.

Traditionally, researchers assigned magnitudes to historic earthquakes by mapping the shaken areas. The Brookings quake rattled a broad enough area to warrant a magnitude of 6.7, according to this method.

But that approach tends to give conservative estimates of past quakes when matched against specific descriptions from newspapers and other records that place people at points near the earthquake's center, Bakun said.

He found that the 1873 quake's effects exceeded those of all others in the region, including modern quakes with measured magnitudes of 7, so he has assigned the Brookings earthquake a new magnitude of 7.3.

The revised magnitude estimate means it was the biggest earthquake on record in Oregon and the second-strongest earthquake known in the Northwest, after a magnitude 7.4 quake in the North Cascades of Washington in 1872.

Wong suspects the source of the 1873 Brookings quake was the Gorda Block, a huge chunk of plate off Northern California and southern Oregon believed to be under extra stress because it sits near the junction of three colliding plates.