Great Shake Out: What You Need To Know

Posted by Tiffany Watson on

On 10/18 at 10:18am, I found myself under a desk in Portland, Oregon. This happens annually for me. No, I am not in the habit of dropping a pen or a mid-morning sweet at the same time each year. I am in the habit of practicing my duck, cover, and hold on skills.

Every year in October, we have the Great Shake Out in preparation for the potential earthquake along the Cascadia subduction zone. About 570,000 were registered across the state this year which is down from last year’s 580,000. I have to be honest, while I remembered to do the drill; I forgot to register. I hope the dive in numbers is for a similar reason.

Preparedness programs are vital in educating our local community about Cascadia and how to survive the impact of an 8 to 9 magnitude quake. They give great tips and resources for securing bookshelves, making preparedness kits, and more importantly turning off your natural gas valves. They even have a series of videos that show how to react in varying situations during a quake.

While I feel that preparedness programs and readiness campaigns are vital, my concerns always shift to the aftermath of Cascadia. In the city of bridges we are likely to go from 14 bridges to merely 3 in the post Cascadia climate. Here are a list of the bridges and how they will fair or not fair the earthquake. You can review a more extensive list at the at KGW8.


  • Interstate Bridge
  • Steel Bridge
  • Broadway
  • Hawthorne
  • Ross Island

Extensive Damage (unusable)

  • Morrison
  • Burnside
  • St. John

Approaches likely to Collapse (still standing but unusable)

  • Marquam
  • Freemont
  • Glen Jackson

Minor Damage (usable)

  • Sellwood
  • Sauvie Island
  • Tilikum

Sellwood, and Tilikum will be vital bridges in connecting the east and west of Portland crossing over the Willamette in the aftermath of Cascadia. We at Overcup are particularly aware of how well Tilikum will fair in the aftermath as our current book Tilikum Crossing: Bridge of the People goes into great detail about the research on the earthquake zones in Portland and the potential impact on the Tilikum bridge design. All the bridge designs proposed reflected the heightened awareness of earthquakes in our region.

Suffice to say Tilikum will most definitely be standing after the ground has stopped shaking. In the aftermath of Cascadia, Tilikum will live up to its name as the bridge of the people, because while Sellwood will likely be utilized for reconstruction efforts and supply runs, Tilikum will likely be the only bridge available for the people of Portland to cross.

As if there weren’t more to worry about the Oregonian reported on 10/23/2018 that new faults around Mount Hood have been discovered which could be capable of a 7.2 Magnitude earthquake.

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