A couple of large earthquakes struck the Ring of Fire in the last 2 weeks: a magnitude 7.8 in New Zealand on November 14th and a 6.9 (according to USGS) on November 21st off the coast of Japan.
I’m fascinated by earthquakes, particularly since I’ve made a decision to focus my career on earthquake resilience. But even if you’re not as into them as I am, the awesome power of earthquakes was undeniable last week in New Zealand. And the Japan earthquake is another reminder of the need for preparedness in the Pacific Northwest.
Landslides, open fissures, stranded cows, and the seafloor lifting up out of the ocean are the images that struck me the most.
This drone video of a ground fault rupture in New Zealand looks like Lord of the Rings style special effects. I can easily imagine an army of orcs falling into the ground as it opened up:
And here’s a good article from CNN about the seafloor being raised. The coast has been permanently changed in a dramatic way (unless an earthquake reverses it):
http://www.cnn.com/2016/11/18/asia/nz-earthquake-pics/
Regarding Monday’s Japan earthquake, the Japan Weather Agency is calling it an aftershock from the 2011 magnitude 9.0 megaquake. It caused a small tsunami and seems to have shaken people up a bit (bad pun intended) but caused little damage.
It’s been estimated that we have a 37% chance of experiencing an 8.0 or higher Cascadia Subduction Zone earthquake in the next 50 years. This is a helpful statistic and I intend to bring it up often. The main application for us in the Northwest is that we have a high risk of this event occurring if we intend to live in this region for long. It makes sense to prepare for it, but once you start thinking of the implications, it quickly becomes overwhelming from the individual level up to the state agencies. The bottom line is that an adjustment in lifestyle is needed for all of us living in this region. More to come on this topic…
How will a Cascadia megaquake compare with these recent earthquakes? The magnitude will be greater; between an 8.0 and 9.0 and possibly even higher. Ground fault rupture as shown in the video above won’t likely be an issue, at least not a primary one, as the fault is off the coast between the continental and oceanic plates. Vertical displacement will likely occur, as the coast is expected to drop on the order of 6 feet relative to sea level. This, along with the accompanying tsunami, has drastic implications for the low lying coastal areas. Strong ground shaking over a huge region will damage older infrastructure like brick buildings and 100 year old homes not attached well to their foundations. Landslides are to be expected throughout the region. Soil will liquify in saturated sandy soils such as near rivers. This has terrible implications for industrial areas like northwest Portland and just south of downtown Seattle near the Duwamish Waterway.
My personal mission is to help inspire as many individuals and families as possible to be resilient when this event occurs. If you’ve started preparing or making lifestyle changes, I’m interested in hearing from you as I’m sure I’m not the first person to do so. I also want to hear from those of you who want to do something but are not sure what to do. What are the questions you have and what concerns you the most?
Making ourselves and our region more resilient is a marathon, not a sprint. So, take a breath and put some thought into this topic. Don’t lose sleep over it, take action instead!