Cascadia’s Fault Tells How Scientists Uncovered the Cascadia Subduction Zone

The jacket copy for Cascadia’s Fault touts it as a disaster book, one that prophesies doom for the Northwest and comes with the warning that an earthquake like the recent one in Japan “could happen tonight.” The copy also appears to be capitalizing on the Chile and Japan subduction zone earthquakes of the last two years, to try to panic the reader into buying the book.

A foreword by Simon Winchester expands on this idea by claiming that recent earthquakes on the Pacific Rim have furnished the trigger for an impending doomsday quake off the coast. But after the rush of stories over the past three months about the threat of a subduction zone earthquake and tsunami, you probably already know that it can happen here. The question for the browser is: Why do I need to read an entire book about the subduction zone?

Well, Jerry Thompson has produced a book that’s not really all that alarmist: In Cascadia’s Fault he’s primarily telling a detective story of sorts, about how scientists uncovered the subduction zone. If you’ve been listening to the subduction zone warnings and want to know more about the basis for them, Thompson’s book delivers that knowledge. He begins at the start of the tale: the 1960s, when the massive 1964 Good Friday earthquake in Alaska and the maturation of plate tectonics theories started leading seismologists to look for evidence of a subduction zone off the Pacific shore.

The narrative then describes the work of Northwest scientist Brian Atwater in the 1980s, when he discovered that groups of cedars along the coast had been drowned by subduction zone tsunamis in centuries past, creating ghost forests. It also chronicles the work of recent years, as seismologists have developed more and more details about the evidence for a long series of earthquakes off the coast, including one in winter 1700 that we can date precisely because of Japanese records of an orphan tsunami striking Japan’s coast on January 27, 1700.

Thompson’s narrative is essentially a fairly calm, pedestrian, painstaking tale of scientific knowledge that’s much like the patient work of the seismologists and geologists who discovered the subduction zone. That tone is disrupted at the end, when Thompson paints an ugly, overwrought scenario of the damage an earthquake and tsunami will do to the Northwest (complete with collapsing skyscrapers and a complete regional blackout).

He also surveys the set of deadly earthquakes in 2010 and 2011, with the concluding message that his reader needs to “get up off the couch and do something” to prepare for the disaster. But the story he’s told in this book is almost entirely about the background to this ever-present danger.

The ideal audience for Cascadia’s Fault is someone in the Northwest who doesn’t know a lot about geology, but is aware of the subduction zone, and wants to get more information about it without having to read the technical literature. Of course, the intended reader of the book is also a coastal resident, but a subduction zone quake will hit the entire region hard, and it’s something for people around Seattle to know about too. Think of how badly Japan’s subduction earthquake impacted Tokyo, and translate that to this side of the Pacific.

Thompson has approached this story from his perspective as a TV documentary producer and correspondent who’s worked on the subject as a layman, putting together a handful of documentaries on the issue over the past 25 years. The education he received from making those documentaries is the basis for this book. He makes some mistakes–namely by omitting a detailed map of the subduction zone and including irrelevant pictures of the 1906 and 1989 quakes in California–and professionals in geology might take issue with the fact that this is not a technical explication of the subduction zone.

But then, Thompson isn’t a professional: he’s writing about the subject as a fairly average Northwest resident. In a sense, Thompson reflects his intended audience: he’s simply very curious about the subduction zone danger, and Cascadia’s Fault relays to the reader what he found out.

In closing, I should mention that an especially interesting and timely element of Cascadia’s Fault is the story of how Pacific Gas & Electric built the Humboldt nuclear plant near Eureka in 1963. In 1983, after the 1964 Alaska earthquake and tsunami that hit the Northern California coast, the discovery of an active fault near the Humboldt plant, and the Three Mile Island crisis in 1979, the utility shut down the plant for good.

The Washington Public Power Supply System (better known as “whoops,” and now called Energy Northwest) never finished the two-unit Satsop nuclear plant it hoped to bring online in the 1980s, and Portland General Electric’s Trojan nuclear plant near Longview is long gone as well: So, there are no coastal or near-coastal nuclear plants that allow us to envision a replay of the Fukushima Daiichi crisis in the Northwest. We do still have nuclear waste in the region, though.