Cascadia's Fault

by Jerry Thompson

  In Haiti on January 12, 2010, a magnitude 7.0 earthquake destroyed huge sections of the capital city of Port-au-Prince, killing more than 200,000 people. The island of Hispaniola sits on the rim of the Caribbean plate, which is being shoved westward by the North America plate as it dives underneath. But here again the real story was about the exposure to risk caused by poor construction quality. Buildings collapsed and people died not for lack of warning but because poverty and shabby construction practices made the tragedy inevitable.

  Little more than a month later, on February 27, 2010, another big subduction earthquake struck the coast of Chile. At magnitude 8.8 it released approximately five hundred times more energy than the Caribbean shock yet it killed far fewer—roughly seven hundred lives were lost in Chile compared with the 200,000 in Haiti. Observers commented that construction quality in Chile was definitely better because building codes have been strictly enforced ever since their last big quake in 1960—at magnitude 9.5 still the largest rupture ever recorded.

  The February jolt occurred on the same fault, twenty-two miles (35 km) beneath the sea floor, and apparently picked up right where the last one stopped. It ripped the next four-hundred-mile (640 km) segment of the subduction zone and probably relieved most of the remaining stress built up in the system. That was the good news. But there was more.

  Because the 1960 quake did not rip the entire fault, scientists expected the next segment to go at any time. So several groups of researchers had installed an extensive array of GPS monitors to keep track of the strain build-up. Computer models (including one by Kelin Wang at PGC on Vancouver Island) then made predictions of how much the fault would move when the last segment finally did break.

  On February 27 the predictions turned out to be right on the money. Almost ten feet (3 m) of nearly instantaneous horizontal motion was measured by GPS instruments at Concepción. The land lurched sideways nearly nine feet, just like Wang’s model projected. Which is the same kind of movement Herb Dragert and Mike Schmidt expect to see in Victoria when Cascadia rips loose. Scientists can now be fairly confident in predicting which part of a fault is likely to break, how far it will move, and how large the jolt will be.

  But in Chile other positive factors were at work as well. One of them was a higher level of public awareness. Because enough people remembered 1960, they knew what to do when the ground started to rumble. Those living in danger zones near the beach immediately ran to higher ground without waiting for someone in authority to issue an evacuation order. According to Kelin Wang, “Numerous lives were saved by this kind of self-evacuation . . . The importance of educating the public far exceeds that of warning buoys.”

  And then it happened again. On Tuesday, February 22, 2011, a strike-slip fault near Christchurch, New Zealand, ruptured in a magnitude 6.3 earthquake that killed more than a hundred people outright and buried hundreds of others in rubble. This time two tectonic plates ripped past each other horizontally, like the San Andreas plates had done. So it wasn’t a subduction quake like the ones in Chile or Alaska or Cascadia (no heaving up of the ocean floor and no tsunami), but it was a rupture in another corner of the Pacific region’s infamous Ring of Fire.

  Less than a month later, on Friday afternoon, March 11, 2011, another segment of the Ring of Fire tore apart in a magnitude 9 earthquake that did jack up and shift the ocean floor off the northeast coast of Japan near the city of Sendai. The shockwaves lasted between three and five minutes and caused skyscrapers in Tokyo—231 miles (373 km) away—to sway like trees in a strong wind. The tsunami was seen around the world almost instantly, covered live by Japanese television crews in breathtaking and heartbreaking detail for hours on end. We were all able to witness immediately the apocalyptic extremes of seismic chaos.

  Rolling balls of flame and thick smoke billowed from ruptured tanks at an oil refinery. A farm family’s home burned furiously as it was carried away—floating atop a tangled mat of splintered lumber and logs, twisted sheets of metal from busted barns and sheds—all of it swept across the coastal lowlands on a thirty-foot (10 m) wave, a churning tsunami gumbo of black soil and seawater. Large commercial fishing boats were torn from their moorings and tossed against concrete breakwaters. The boats bounced off the breakwaters and then slammed like battering rams into the walls of nearby buildings. Hundreds of cars and trucks were carried away on this roaring tide of muck, right before our eyes. Were there people inside? How could there not have been?

  Mud-spattered survivors looking stunned and forlorn wandered through rubble in search of family and friends. Hundreds of people sprawled, exhausted and in shock, on the floor of a school gymnasium, nesting in rucked-up blankets, their coats and shoes and “grab-and-go” bags gathered around them like imaginary walls to fend off the ongoing nightmare.

  Food store shelves were stripped bare and long lines of cars appeared at gasoline pumps, the fuel supply running dangerously low. And still, somehow, all of this post-quake scramble was happening in a relatively organized and orderly manner, presumably because the Japanese had experienced many smaller quakes and tsunamis before and knew this was coming. They had planned and drilled and rehearsed. The atmosphere seemed amazingly calm and eerily quiet. I sincerely doubt it will be this peaceful when the same thing happens to North America.

  But if pride comes before a fall, then the construction of nuclear reactors near an active fault zone has to rank among the most dazzlingly optimistic—or stunningly foolish—things that modern nations have ever done. Not just in Japan, but in California and many other places around the globe. Until we watched those plumes of gray-white smoke rising across the Japanese coast as the roof and outer walls of the Fukushima Daiichi reactor complex began to vaporize and then collapse—until we saw it with our own eyes—the horror of a nuclear meltdown seemed like the last thing a quake or tsunami survivor should have to worry about. Scientists, engineers, and government officials have led us to believe that nuclear plants are built to withstand seismic shocks. Now I guess we know better. For those living on North America’s own locked and loaded segment of the Ring of Fire, the question now must be: are we next?

  Even though seismologists still cannot predict when Cascadia’s fault will break, pretty much everybody who has lived out west for a while knows deep down inside that a megathrust quake will eventually happen. Sure, on any given day the mathematical odds of a magnitude 6 or 7 under downtown Seattle or Vancouver are higher than for a magnitude 9 from Cascadia. Smaller quakes do happen more often than big ones. That’s why most emergency managers have been told the local rumble is still their worst scenario. And for any given point on the map, that’s absolutely right—the local quake may cause more intense damage to that particular city than Cascadia would.

  But Cascadia’s fault is going to cause damage to all the cities and towns along a swath more than 800 miles (1,300 km) from north to south and as much as 125 miles (200 km) inland. So the cumulative damage will be far greater than the impact of any local quake on any single city. The enormity of what’s about to happen in the Pacific Northwest is almost inconceivable. And that’s only part of the reason why Cascadia is not yet as infamous or worrisome to many people as the San Andreas already is.

  The main reason why emergency managers and even elected officials tend to focus almost exclusively on their own local concerns is that their jurisdictions demand it. As Lori Dengler at Humboldt State University pointed out, the Governor’s Office of Emergency Services in California does not have a mandate to worry about what might happen in Oregon or Washington, much less the consequences for British Columbia. But as soon as Cascadia breaks we’re all going to be out there in the rubble together, and that’s a hell of a time to get to know each other.

  If the biggest, wealthiest, most technologically advanced nation in the history of the world could not cope with Hurricane Katrina any better than it did, how on earth will it cope with Cascadia? How will Canada? And here’s the thing: with Katrina there was at least forty-eight hours’worth
of muscular wind and howling rain before the main part of the storm hit New Orleans. When Cascadia’s fault ruptures there will probably be no warning at all.

  So what should we do—slit our wrists? Absolutely not. Even after more than twenty-five years of watching people ignore the obvious, I still think we can survive this thing better than we might imagine. As Patrick Corcoran said time and time again—yes, it is likely to happen; yes, it will be bad; and yes, education can make it better. So go out there and get some. Join an emergency preparedness group. Take a first aid course. Just get up off the couch and do something.

  Bottom line: we’re not all going to die! The vast majority of us will survive the big jolt from Cascadia. The key issue is how well we endure the aftermath. And that depends totally on how much time and attention we invest now in preparing ourselves, making our communities resilient.

  Two anecdotes told by Lori Dengler when we interviewed her for the 2008 ShockWave documentary stick in my mind and give me something to hang onto. A bit of hope. After the Sumatra earthquake and tsunami Dengler traveled to the disaster zone to study what had happened and how it might apply to us in North America. Like Chris Goldfinger and others she came back to her laboratory on the north coast of California with a huge volume of new data and insights about how a subduction quake works and what a tsunami will do.

  But the story of Tilly Smith was one she simply had to tell anyone who would listen. The film crew and I definitely listened. Tilly Smith, a ten-year-old British schoolgirl on Christmas holidays with her parents in Thailand, was strolling across the sands of Mai Khao Beach near Phuket when she noticed frothing bubbles on the surface of the sea as the tide started to recede quite suddenly. Two weeks before Christmas break Tilly had learned about tsunamis in her geography class. Old film footage of a wave that hit Hilo, Hawaii, back in 1946 had evidently left an indelible memory because she immediately recognized the same thing and ran to tell her parents.

  “I told my mom again and again,” she squealed later in a television interview, “and I was hysterical at this moment, saying, you know, ‘There’s going to be a tsunami! There’s definitely going to be a tsunami!’ You know? Just believe me!”

  “Her mum and dad did believe her,” said Dengler, “and they managed to clear everybody off the beach. Got them into the hotel. And they managed to vertically evacuate and get about a hundred people from that hotel into the upper floors. And not a single person died in that particular hotel complex. All because a ten-year-old girl had knowledge! All because she recognized the natural warning signs.”

  Even more to the point of our survival in Cascadia’s shadow was Dengler’s story from a personal visit to Simeulue Island, a tiny tropical outpost roughly ninety miles (150 km) off the west coast of Sumatra: one of the nearest human settlements to the epicenter of the magnitude 9.3 earthquake of Christmas 2004.

  “Simeulue Islanders are a relatively homogeneous people,” Dengler explained. “They’re still very much in touch with their tribal identity and a strong oral tradition.” Legend has it that a quake and tsunami struck Simeulue in 1907, killing many local residents. Those who survived evidently told this story to their children and grandchildren, which may have been why they knew what to do when the same thing happened again in 2004.

  “Langi village was the village closest to the epicenter of that earthquake,” Dengler continued. “They felt that earthquake very, very strongly. And in fact it damaged about 25 percent of their structures. The first tsunami waves arrived at that northern part of Simeulue Island only eight minutes after the earthquake,” she said. “They had very, very little time.”

  But because their oral history had been kept alive, they knew exactly what had to be done. According to Dengler, everyone in Langi knew that “when you feel a really long strong duration earthquake, you immediately grab your children, help grandma—and get yourself up to high ground. And not only did they go up to high ground, they actually had an entire temporary village—materials to make an entire temporary village up there. They had posts; they had aluminum for roofs; they had water; they had food.” She sounded impressed, almost amazed. And so was I. Best of all, however, was the conclusion to her story. After the earth shock came the waves.

  “The waves were enormous,” said Dengler. “In Langi village every single house was completely wiped off the face of the earth. The only thing left were the concrete foundations.” She shook her head. “Completely destroyed. They lost their animals; they lost their fields.” But? And I knew there had to be a but. “Not a single man, woman, child—not a single old person—died,” Dengler said. “Not one!”

  Thinking about it now I’m pretty sure I had to look away. We both had tears in our eyes. “Oh, it was an amazing story,” she continued. “To me the most important lesson from Indonesia is that if you have an aware community, you can all survive. But you need to keep that as a part of your culture. You need to make sure that it’s not forgotten from generation to generation.”

  And now we on the west coast of North America must learn to do the same. Dengler put it in perspective: “Most people here are going to survive a Cascadia event. But a Cascadia event is going to have more people having to be on their own and self-reliant and resilient for a longer period of time than any other event that I can think of.” So there’s more to it than duck-and-cover drills in schools and tsunami evacuation exercises.

  We have to gather at the neighborhood level and in family groups to come up with personal survival plans that instantly come to mind no matter where we are when it finally happens. With busy lives that seem like a game of musical chairs, we need to know what we’ll do wherever we happen to be when the music stops: at home, at work, or at play, as Patrick Corcoran likes to say.

  We also need to think hard about mitigation, about renovating and upgrading essential structures such as hospitals, schools, and other public buildings that we’ll need for emergency shelters. Computer models have already shown some communities that their police stations, fire halls, and other important infrastructure may be wiped out in the coming flood. City and village councils should already be thinking about how and when (and how to afford) to move some of these facilities or rebuild them on safer ground. Governments need to pass legislation to rezone the dangerous parts of town so that if public or private buildings are destroyed by Cascadia’s fault, people will know ahead of time that they cannot and should not expect to simply rebuild in the same spot, re-creating the same fatal vulnerabilities.

  Eddie Bernard of NOAA summed it up nicely. “Don’t we as a society want to save the community?” he asked. “That is—you want to have a community to return to. You want to have a hospital to go to. You want to have schools that your children can go to. You want to have teachers in those schools. All those things were wiped out in Sumatra. They lost everything. So that’s a lesson that we should take away—we should be building our society so that it’s resilient to the next tsunami.” And even though the job sounds daunting, Bernard remains an optimist. “What we don’t want to have is just the assumption that it’s hopeless. Because it’s not.”

  I agreed. And so did Chris Goldfinger: “It doesn’t have to be such a disaster. It’s only a disaster if we don’t do something.”

  AFTERWORD

  Lessons from Tohoku—A “Worse Than A Worst-Case Event”

  At magnitude 9.0 the Tohoku-Oki earthquake on March 11, 2011, was the strongest ever to hit Japan. The main shock was followed by more than nine hundred aftershocks, sixty of which measured magnitude 6.0 or higher. Three of them reached magnitude 7.0 or higher. An estimated twenty thousand people are dead or missing, more than 95 percent of whom were killed not by the quake but by the tsunami that followed. The U.S. Geological Survey (USGS) estimates that 332,395 buildings were either destroyed or damaged. At a cost of more than $309 billion, this seismic event has become the most expensive natural disaster in history. And it all began with a quake exactly like the one Cascadia’s fault will generate along North America
’s west coast.

  At home in British Columbia, it was Thursday night, March 10, 2011. In Japan it was Friday afternoon. Out of the blue I received an urgent email from Chris Goldfinger of Oregon State University.

  It was a madly dashed mass-mail-out to his wife, colleagues, and friends around the world. It basically said that he was okay, that he had survived the quake, and that he would tell us more as soon as he could. At that very moment, I was watching coverage of the largest tsunami in a thousand years as it rolled over the top of a thirty-three-foot-high (10 m) seawall in northern Japan.

  Goldfinger just happened to be in Tokyo attending a science conference about the Sumatra earthquakes of 2004 and 2010. “It was the third earthquake of the week,” he blogged a short time later. Japan had been rattled by a magnitude 7.4 earlier in the week and a smaller one the next morning, both of which may have been foreshocks.

  The jolt on Friday afternoon, however, was definitely the main event. “At first, it seemed no larger than the others . . . But instead of stopping at a few seconds, or maybe a minute as the earlier ones had, this one kept going, and going, and going.

  “In a room full of seismologists, we timed the gap between the P-wave and S-wave arrivals, and then started thinking about whether we should get out of the building. The desks looked really flimsy, so duck and cover didn’t look good at all . . . After about a minute of shaking, we were all outside in the courtyard watching the flagpole on the roof of the seventh floor whipping through sixty degrees. And the dry rattle of the trees with last year’s leaves as they shook . . .