The Big One: The Cascadia Earthquakes and the Science of Saving Lives

by Elizabeth Rusch

Overview

No one ever thought the Pacific Northwest was due for an earthquake, let alone a catastrophic one. But geologists are transforming our understanding of the grave dangers the population in the region of Cascadia face—will there be a big one? And what can be done to save lives?

America's Pacific Northwest has relatively few earthquakes—only a handful each year that cause even moderately noticeable shaking. But a couple decades ago, scientists discovered a geological feature running along the coast that in other parts of the world regularly triggers massive earthquakes of 8.0 magnitude and higher. Were there once massive earthquakes in this part of the world? Geologists think there were. Now a small group of scientists are studying things that you might not think have anything to do with earthquakes—marsh soil, ocean sediments, landslide debris, and ghost forests—and they have reason to believe that the Pacific Northwest is likely not as idyllic as it was once assumed. The population is likely in grave danger of a massive earthquake at some point. What can be done? The big one can't be stopped, but scientists are working tirelessly to learn as much as they can to prepare.

Product Details

ISBN-13:	9780544889040
Publisher:	HarperCollins
Publication date:	08/18/2020
Series:	Scientists in the Field Series
Pages:	80
Product dimensions:	9.10(w) x 11.10(h) x 0.50(d)
Age Range:	10 - 12 Years

About the Author

Elizabeth Rusch is the author of You Call This Democracy?, a finalist for the YALSA Award for Excellence in Nonfiction for Young Adults, and more than a dozen acclaimed children’s books, including picture books, middle grade, fiction, nonfiction, and a graphic novel. In a starred review Kirkus called her book The 21: The True Story of the Youth Who Sued the U.S. Government Over Climate Change a “nail-biting account of a still-unresolved landmark case.” She lives in Portland, Oregon, with her family.

Read an Excerpt

CHAPTER ONE

The Mystery of the Missing Earthquakes

NOT TOO LONG AGO, when your grandparents were kids, their teachers and textbooks had no explanation for what created mountains. No one knew why some ranges loomed steep and jagged while others lay low, round, and smooth. Geologists had no good ideas about what caused earthquakes. We didn’t even know how continents were formed or why some of their coastlines matched like pieces of a jigsaw puzzle.
      “Until surprisingly recently, science had no good answers to these very basic questions,” says Chris Goldfinger, professor of geology and geophysics at Oregon State University. “I’m talking about up until the 1960s, geologists just had no idea how or why any of these things existed.”
      More than a hundred years ago, a German weather forecaster named Alfred Wegener took a shot at explaining how continents formed. Scientists had long ago noticed that the coastlines of various continents looked like they would fit together. Wegener discovered that the rocks and fossils found on the distant coastlines were, surprisingly, also similar. And the grooves scraped into the landscapes by glaciers during the Ice Age seemed to line up from one continent to the other.

“Those observations should have rocked every geologist on the planet.”

Wegener proposed that once, long ago, the Earth had only one big continent that split and drifted apart to become the continents we know today. He called his theory continental drift.
      “Those observations should have rocked every geologist on the planet,” says Chris. “But that didn’t happen. They dismissed him.” After all, Wegener was an outsider to geology and he couldn’t explain how or why the continents had moved.
      So, Wegener’s theory was forgotten.
      Then, during World War II, submarines scouring the seas for German U-boats found an odd structure on the ocean floor—a ten-thousand-mile-long (16,000 kilometer) ridge running through the Atlantic Ocean from north to south, like a huge zipper. Geologist Marie Tharp mapped similar ridges in the Pacific Ocean. Over the next few decades, scientists discovered that while rocks on either side of the ridges were old, the rocks near the ridges were newer. Something was creating new sea floor at the ridges and pushing land away on both sides.
      “Right about then, Wegener’s theory came back to life,” says Chris. “People realized, uh-oh, maybe this guy was actually right. Maybe the Earth’s crust is moving around.” Geologists quickly embraced a powerful idea that seemed to explain everything: the theory of plate tectonics. According to this now well-established, widely accepted theory, Earth has a crust—a hard shell of rock—that is broken into huge plates. These plates float on a layer of melted rock, drifting slowly apart in some places and bumping into each other in other places.
      Plate tectonics explained mountain formation: Plates crash into each other, pushing up the land. Tall, jagged mountain ranges are young; lower, gentler ranges are older and have eroded over time.
      Plate tectonics explained earthquakes: As plates slide along each other, sections can get stuck. Pressure builds until that section suddenly gets unstuck, shaking the ground nearby.
      And plate tectonics explained really big earthquakes: Plates collide, and the heavier plate pushes under the lighter plate in a process called subduction. Sometimes plates get stuck along the whole zone where the plates meet. The upper plate bows upward, like a yardstick that is being pushed together at both ends. Pressure builds. Finally the top plate releases and everything that was bowed up snaps down, shaking a huge length of land. This rupture causes megaquakes, magnitude 8.0 and up earthquakes that shake for minutes rather than seconds.

Maybe pressure was building all along the Pacific Northwest coast, ready to unleash a megaquake.

But plate tectonics did not explain the Pacific Northwest. About fifty miles (80 kilometers) off the coast, running from British Columbia to Northern California, lies the 620-mile-long (1,000-kilometer) Cascadia Subduction Zone (CSZ), where a heavier plate pushes under a lighter one. Subduction zones circle the Pacific Ocean, creating the Ring of Fire, a geographically active region where 90 percent of the Earth’s quakes—and all of the biggest earthquakes—occur.
      “But Cascadia seemed just dead silent,” Chris says. “It was basically the only subduction zone in the world that didn’t seem to have earthquakes.” There were three possible explanations: Maybe silt, acting like grease on wheels, kept the plates moving steadily. Perhaps the plates had simply stopped moving. Or, most frighteningly, maybe the plates were locked and had been locked for a long time. Maybe pressure was building all along the Pacific Northwest coast, ready to unleash a megaquake.
      The lack of massive earthquakes in the Cascadia Subduction Zone was a baffling mystery for scientists. “We’ve got this great theory, and it fits everything, except it can’t explain this,” Chris says. “And so Cascadia just sat like a white elephant in the corner and everyone just tippy-toed around it.”
      For almost forty years.

THE CASCADIA SUBDUCTION ZONE

Much of North America sits on the North American Plate. Just offshore from British Columbia, Washington, Oregon, and Northern California, three smaller, heavier plates—the Juan de Fuca, Explorer, and Gorda Plates—press into the edge of the lighter North American Plate. As the plates slowly collide, the three smaller plates smash beneath the North American Plate, creating the Cascadia Subduction Zone. The inset shows where the CSZ is located on the Ring of Fire.

Editorial Reviews

★ "A first-rate resource." –School Library Journal, STARRED review "[T]he information flow across chapters is exceptionally smooth and well organized. As customary for the Scientists in the Field series, the snapshot vibe of the generous photo illustration lends immediacy to the highlighted research."–The Bulletin of the Center for Children's Books  —

From the Publisher

★ 08/01/2020

Gr 5–8—Up until the 1960s, geologists had little idea what caused earthquakes. Following a discovery initially made by geologist and cartographer Marie Tharp during World War II, scientists revisited the idea of continental drift, an early 20th-century theory developed by German meteorologist Alfred Wegener. In the decades since the return to Wegener's theory, the science of plate tectonics has helped clarify why earthquakes happen and how they might be accurately predicted. Several chapters detail scientific fieldwork, including climbing mountains to set and maintain instruments and visiting remote ponds to gather core samples of the muck beneath. The work described is assisted by graduate students or even undergraduates, providing encouragement to budding scientists. The book is elaborately illustrated, often with full-page color photos of scientists and students at work, along with relevant and clearly presented maps and diagrams. Closing chapters outline widespread efforts to prepare for a devastating earthquake in the northwest U.S. In addition to the recommended further reading, Rusch offers a lengthy source list, including personal interviews as well as articles, websites, and books. VERDICT A first-rate resource. Highly recommended for elementary and middle schools, particularly those with a STEM focus.—Bob Hassett, Luther Jackson M.S., Falls Church, VA

School Library Journal