The Wave: In Pursuit of the Rogues, Freaks and Giants of the Ocean by Susan Casey

Author:Susan Casey
Language: eng
Format: mobi, epub
Tags: Life Sciences, Ecology, Oceanography, Nature, Waves & Wave Mechanics, Science, Travel, Geology, Oceans & Seas, Special Interest, Sports & Recreation, Surfing, Adventure, Ecosystems & Habitats, Rogue waves, Earth Sciences
ISBN: 9780767928847
Publisher: Random House, Inc.
Published: 2010-09-14T01:16:45.364000+00:00

Wherever peppy earthquake action meets ocean, there will be giant waves. Which means not only Alaska but the entire North American west coast is poised to produce them. If you zoom out on the satellite map and trace the Pacific basin’s outline you’re looking at a path that scientists refer to as the Ring of Fire. A majority of the world’s active volcanoes reside along this arc, both above water and below. It’s the most seismically active place on earth, and the source of 80 percent of all tsunamis. As the Pacific and North American plates—two of the continent-size jigsaw pieces that cover the earth’s molten core—grind against each other off California, Oregon, and Washington, those movements create earthquakes. If, in the shaking, the land lurches vertically and enough water is displaced, tsunamis will arise.

Lately geologists have refined their sleuthing methods, taking core samples from seabeds and coastal areas and then searching the layers for odd deposits—seashells crushed in alluvial sand a mile inland, for example, or coral that somehow made its way to the top of a two-hundred-foot bluff. Sometimes they find “ghost forests,” places where the trees have been snuffed out by being buried, drowned, torn away, or poisoned by salt. Whenever the ocean leaves these kinds of calling cards, scientists can infer that waves once swept over the area with great force.

Using these techniques, they discovered that a tsunami rivaling the one on December 26, 2004, in Indonesia, had been generated on January 26, 1700, off the Oregon coast, by an estimated 9.0 earthquake. (This was surprising: at the time, the six-hundred-mile-long area that ruptured, known as the Cascadia subduction zone, had been considered kind of sleepy.) No visual description of the tsunami’s impact on the Pacific Northwest has survived, but it was likely impressive: the waves’ fingerprints show up in the geological record all the way from northern California to Vancouver Island.

Proof that this earthquake spawned a tsunami solved a longstanding mystery: the source of the twenty-foot waves that had walloped six hundred miles of Japan’s Pacific coast at that same time, flooding villages and harbors, wrecking boats, killing people, and causing fires that burned down homes. By necessity Japan has always been a tsunami-savvy place—no country is more vulnerable to giant waves—but on this occasion people were caught off guard because they hadn’t felt an earthquake. Japanese records describe the day as having “unusual seas” and “high waves.” They never dreamed the waves had come from clear across the Pacific.

These days the Cascadia fault is under constant scrutiny. The combination of its location near a crowded coastline (a serious tsunami originating there would definitely hit California) and some recent spooky behavior has scientists worried. There are strong signs that pressure is building on the fault again, and that it’s likely to grumble loudly in the not-too-distant future. In 2005 a California Seismic Safety Commission report stated bluntly that “the Cascadia subduction zone will produce the State’s [sic] largest tsunami.” The report went on to predict

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