PBS Terra exclaims 'Wait...The Worst Possible US Disaster Just Got EVEN WORSE?!?'

The 4th of July is over and my blog has already passed its monthly page view goal, so it's time to write about topics worth sharing in August. Fortunately, PBS Terra's most recent video fits the bill, Wait...The Worst Possible US Disaster Just Got EVEN WORSE?!? (Cascadia Megaquake).

The Big One is coming and it could be far worse than anyone imagined.

The Cascadia Subduction Zone, just off the Pacific Northwest coast, is building toward a massive earthquake and tsunami. But new research reveals an even more terrifying possibility: widespread toxic spills, infrastructure collapse, wildfires, and deadly gas plumes. All triggered by a single seismic event.

In this episode of Weathered, we dig into the science behind the Cascadia Megaquake, why the Pacific Northwest is especially vulnerable, and how climate change could make it worse. We explore what you can do to stay safe and why your community might be your best line of defense.

This video is the latest in a series that began with PBS examines the risks from a major earthquake in the Pacific Northwest and continued with PBS Terra explains 'Here's EXACTLY What to Do When the Next Megaquake Hits: Cascadia Subduction Zone', PBS Terra asks 'What's the ONE THING You Can Do To Survive a Tsunami?', and PBS Terra explains 'How Scientists Solved the Mystery of a 300-Year-Old Megaquake'. It's also inspired a multi-year conversation between Infidel753, who lives in the Pacific Northwest, and myself that's played out in the comments, which then gets recycled in the next post in the series. This post is no exception. Here's the exchange from January.

Infidel753: The Portland metro area has two million people and Seattle is even bigger. Even if 125,000 people were killed on the Oregon coast and a similar number on the Washington coast, I would still expect the death toll from structural collapses and fire in Portland and Seattle to be much larger.

Me: I looked up estimates of deaths, injuries, and homelessness from a magnitude 9 earthquake in the Pacific Northwest and found these from Surviving Cascadia, themselves quoted from Oregon's Cascadia Rising Exercise document (PDF).

Coastal fatalities (Oregon): 4,800 (4,500 from tsumami, 300 from the earthquake itself)
I-5 corridor fatalities (Oregon): 400 (all from earthquake)
Coastal injuries (Oregon): 6,500 (5,000 from earthquake, 1,500 from tsunami)
I-5 corridor injuries (Oregon): 9,000 (all from earthquake)
Homelessness/needing shelter (Oregon): 520,000 (500,000 earthquake, 20,000 tsunami)
Coastal fatalities (Washington): 9,100 (9,000 from tsunami, 100 from earthquake)
I-5 corridor fatalities (Washington): 300-1,600 (300 earthquake, 0-1,300 tsunami)
Coastal injuries (Washington): 5,000 (2,000 earthquake, 3,000 tsunami)
I-5 corridor injuries (Washington): 7,400 (7,000 earthquake, 400 tsunami)
Homelessness/needing shelter (Washington): 415,000 (370,000 earthquake, 45,000 tsunami)

According to these estimates, more people will die from the earthquake along the I-5 corridor than along the coasts in both Oregon and Washington, but far more will die from the tsunami along the coasts alone (13,500) than the total that will die from the shaking throughout both states (1,100). So, no, the official estimates do not support your expectation that "the death toll from structural collapses and fire in Portland and Seattle to be much larger" than tsunami deaths on the Oregon and Washington coasts.

Infidel753: Very interesting links, thank you. I need to think further about this.

Me: Thanks for linking to the sources of these statistics and the blog as a whole in Link round-up for 18 January 2025. I'm glad to have informed you and your readers.

The statistics quoted are from a 2016 document, but the casualty numbers are higher than in the video, 43,800 total deaths and injuries in the document compared to "over 30,000 casualties" (total deaths and injuries) cited by Tina Dura of Virginia Tech. Surviving Cascadia also cites a 2022 study by Patrick Massey for FEMA that projects 1,100 earthquake-related fatalities, 13,000 tsunami-related fatalities, and 24,000 injured. The death count is substantially the same, but the number of injuries is less than the 27,900 predicted in the 2016 estimate, altough the 2022 report was for a February earthquake and tsunami. Casualties could be higher during the peak of tourist season. Cascadia Rising didn't list a dollar amount, but I can believe the video's estimate of $81 billion dollars of damage.

On the other hand, Luke Hanst of Portland State University added up to 2,500 deaths from toxic gas exposure resulting from burning fuel and chemical storage tanks and hundreds of thousands of people affected, adding tens of thousands of injuries. Even adding the 2,500 deaths to the 400 from the earthquake listed above for Oregon's I-5 corridor would not push it above the 4,800 deaths expected along Oregon's coast, but it does make the risk more even as well as much higher along the interior.

The video added two items of scientific interest, the effects of liquefaction and climate change. I make a big deal of the former when I lecture about earthquakes, especially the 1964 Alaska Good Friday earthquake. I might show this video to my geology students just to reinforce the point. Climate change will make the subsidence along the coast, which the video in January's post showed happening in 1700, even worse.

Finally, this isn't the first time Maiya May has described pro-social behavior in the aftermath of disaster. That might have been in PBS Terra's 'Weathered' asks 'Do You Need a Gun to Survive the Next Disaster?'

For what it's worth, I've seen similar, if not the same, findings about lower crime rates and increased cooperation after natural disasters and wrote about them five years ago in Seeker/DNews is optimistic about how people would behave during the apocalypse. As I wrote then, "that's good news, even if it might not be good entertainment."

Still good news.

That concludes the latest installment in this series. Stay tuned for the first Sunday entertainment feature of July. Awards shows!