It was 1980, the middle of April, when the ground started to shake. For two months, the ground around Mount St. Helens continued to intermittently rumble. Scientists monitored the situation, eventually concluding that volcanic activity was inevitable. Most people evacuated, fearing the widespread destruction that most scientists forecasted. A few, however, decided to stay.
Among those who remained on the mountain was Harry Truman (not the President). Truman operated a lodge on the foot of the mountain and refused to vacate the premises, despite constant warning. Truman eventually had to move his bed to his basement after repeatedly being knocked to the floor by continuing quakes, he remained unconvinced that disaster was imminent.
On May 18, 1980, Mount St. Helens erupted. A large segment of the peak was completely obliterated and Truman’s lodge was completely buried under approximately 150 feet of debris. Truman and his 16 cats were presumed dead.
Dozens of parodies on television programs and in books have portrayed Truman as a lunatic, completely ignoring obvious danger when his world was, quite literally, about to explode.
The reality is that Truman’s story isn’t a unique one. Every day we—the citizens of Seattle– face a similar threat and look right through it.
You see, Cascadia is quite a special place in the tectonic world. While the vast majority of the United States sit on the enormous North American Plate and push up against similarly massive oceanic plates, the corridor from British Columbia down to the Northern tip of California doesn’t push up against the Pacific Plate like the rest of the Western Pacific seaboard in North America. Rather, they border a small jagged piece of tectonic plate called the Juan de Fuca.
De Fuca was a Greek explorer whose journals included drastically inaccurate details. He also claimed to have been marooned by English privateers in Mexico and to have been a friend of the Spanish King Phillip II, despite the fact that there is no sign of his name in royal records.
Everything we know about de Fuca comes to us secondhand from an obscure writer. There are some scholars who would argue that de Fuca may never have existed.
However, the name of a puffed up, arrogant, possibly fictional explorer who reportedly sailed wildly up and down the Western coast of North America bragging about his friends in high places, making radically inaccurate observations and naming things after himself is perhaps the perfect thing to call a tectonic plate as obnoxious as the Juan de Fuca.
Beneath our feet the tiny, shard-like Juan de Fuca plate has been aggressively pushing against the North American plate—several times its size—for thousands of years. The area where the two plates meet is called the Cascadia Subduction Zone.
Calling the area a subduction zone, however, does little to convey the violence that truly occurs there. Geology texts imply that subduction zones are areas where one plate glides beneath another; they suggest a submissiveness of one plate to the other.
Evidently, the Juan de Fuca plate isn’t well versed in elementary geological thought. Rather than sliding neatly below the North American Plate, the Juan de Fuca is crashing against the North American with a vengeance. While it does subduct, it doesn’t do so without a fight—the two plates generate enormous pressure as they press against one another, every so often lurching forward with a jolt.
It’s difficult to convey the tension occurring underfoot. This activity might help you better understand: find a friend and have them hold their hand steadily in front of them, palm-up, at an approximately 30-degree decline. Next, you place your palm on theirs at a parallel incline. In this exercise, your friend’s palm is the tiny, angry Juan de Fuca and yours is the big hungry North American.
Now, push. And push hard. Direct your push toward your friend’s core while he/she directs his/her push toward yours. You should be directing tremendous force at your partner. At first, neither hand should move as tension continues to mount. Eventually, however, someone’s hand will abruptly jolt upward or downward.
That jolt is a subduction zone earthquake, a “superquake,” and it’s terrifying.
In 2005, fearing that citizens and institutions of Cascadia were unprepared for a subduction zone quake, members of the both the public and private sector formed a board to address the issue: CREW, the Cascadia Region Earthquake Workgroup.
CREW’s report is quite comprehensive, discussing the potential impact of different types of quakes in different areas of the region as well as dryly illustrating the potential havoc wreaked on the lives of single mothers and stay-at-home fathers in the event of a large quake.
There are three kinds of earthquakes we face in Cascadia, according to CREW’s report. The first of these, shallow quakes, are caused by the slight movements of faults in the crust and are recorded almost daily. The majority of their impact is limited to slight shaking in the immediate area where the fault movement occurred. There is a faultline running directly beneath the city of Seattle, but because the quakes are so small and localized, there isn’t great cause for alarm.
Intraplate quakes are of more concern. These are caused when fractures form in the Juan de Fuca plate. Because they occur so deeply (nearly 20 miles beneath the surface), their effects are more widespread but are dampened by the distance between the point of rupture and the surface. These are estimated to occur approximately every 10 to 30 years.
In 2001, an intraplate quake was centered beneath the small town of Nisqually, Wash. This magnitude 6.8 quake, according to Seattle’s Office of Emergency Management, took one life, injured 407 people, and caused $2 billion in damage. While the Nisqually quake caused a significant amount of damage and was treated by the media as a large disaster, it was nothing compared to the threat of a subduction zone quake.
Subduction quakes are typically above magnitude 9 and occur at the seafloor where the plates subduct. CREW forecasts total devastation should one of these quakes occur.
They predict that many of the roads and bridges in the I-5 corridor will be lost to liquefaction as the quake shakes the water-saturated sandy soil of Puget Sound and pavement sinks below ground. Several communities are likely to be disconnected from receiving help as the only routes in or out slip underwater.
Depending on the intensity of the shaking, many single-family homes may disconnect from their foundations and sever utility lines. The now free gas could fuel fires while firefighters stand helplessly by, unable to do much given that water lines could also be damaged beyond use.
Larger buildings are at risk of destruction in the event of a subduction zone quake. CREW explains that this is the one area of preparedness where we have definite control. Unfortunately, the area is less than prepared in this regard. The buildings most at risk are URMs, or unreinforced masonry buildings. The report notes that most URMs are brick buildings with concrete or wooden flooring.
“There are thousands of these buildings throughout Cascadia. Even though most URMs are one to five stories, they may not be able to withstand the duration of shaking,” the report claims.
The Spectator, without detailed structural analysis, could not determine whether any buildings on campus are URMs. However, there are a handful of buildings at the university that fit the “brick with concrete or wooden flooring” mould.
It isn’t over yet.
Aftershocks would continue to disrupt structures as survivors waited for aid, likely without power and the ability to communicate. The wait could be long; infrastructural damage is expected to destroy sections of roads and highways.
The real threat of a tsunami also looms. CREW estimates that a tsunami would isolate many coastal communities and lead to dozens of deaths, citing sweeps of 30+ foot waves that could continue to ravage the coast for up to 12 hours.
Seattle’s Office of Emergency Management estimates that a subduction zone quake could claim, in total, 1,000 lives and destroy infrastructure. They make sure to note that URMs and buildings constructed on slopes are incredibly vulnerable, and that our dependence on bridges will make it near difficult for emergency supplies and aid to be delivered.
For comparison’s sake, a 1964 magnitude 9.2 earthquake in Alaska killed 12 people. The resulting tsunami killed another 119.
CREW drew parallels from this Alaskan quake, centered in Valdez, to possible Cascadian scenarios. The equivalent of a subduction zone quake centered on the Juan de Fuca plate, they argued, would have similar effects on Seattle as the Valdez quake had on the city of Anchorage, approximately 120 miles away.
In Anchorage, a landslide destroyed a 30-block area of downtown, two schools, an airport control tower, the entire city’s sewer system. In a city of 55,000 people, 2,000 were left homeless. Nine were killed.
The report also included several pages detailing the long-term after effects of a large subduction quake, discussing the major economic implications of the infrastructure destruction. The implication is billions of dollars in loss, a major decline in employment and tourism, and a long and arduous period of rebuilding and recovery.
Clearly, a subduction zone earthquake would be devastating. You could breathe a sigh of relief that these types of quakes are incredibly rare, occurring in this area, on average, every 300 years.
Unfortunately, it is important to note that the last subduction zone earthquake that occurred in this area occurred on January 6, 1700.
As one PBS NewsHour anchor quipped in April of this year, “Do the math.”
However, aside from fleeing the area, there isn’t a whole lot we can do. However, almost every region on the planet is particular vulnerable to some sort of natural disaster, be it hurricanes along the eastern Seaboard, destructive heat waves across most of the center of the country, or near total water depletion in the Southwestern United States, there really aren’t very many safe places to turn.
Maybe, after all, Truman was on to something. We could spend a lifetime running away from the possibility of random natural disasters and still never get away.
Assuming you are resigned to stay in the area and face the subduction zone quake there are some things you can do to lessen the forthcoming blow. For one, advocating that buildings and bridges be made earthquake-safe. This won’t be an easy transition though. In April, Oregon’s Highway Division Administrator Paul Mather claimed that it would take at least 100 years to make the 1,000 bridges in that state that are still deemed at-risk “earthquake-resistive.”
Second, make sure you know what you are doing. Seattle University does have an emergency plan issued through the Human Resources department and is thus focused on aiding faculty in responding to a disaster should one occur during working hours. Their advice is similar to the advice you should have received in elementary school: if you are outside, move to an open space; if you are inside, get on the ground and try to make your way under a table.
Avoid potentially hazardous objects like windows, shelves or unsecured sharp objects you inexplicably have on your walls (better yet, take these down), or 15-foot blown glass sculptures precariously perched above doorways.
The plan, however, doesn’t provide guidance to those who aren’t on campus. Depending on where you happen to be, your strategy should shift.
For example, if you happen to be on the coast, run like hell for higher ground.
Pat Corcoran, the hazardous outreach specialist with Oregon State’s Extension Service, warned that those on the coast would largely “be on their own when the earthquake strikes” and advised that these individuals make their way to high ground immediately, as the consequent tsunami could hit the coast within minutes.
Really though, all the planning in the world might not do any good if a subduction zone quake hits. Truman may have had the right idea after all; perhaps the best we can do is to cross our fingers and hope for the best.
Dallas may be reached at [email protected]
