Friday, September 2, 2011

Megaquake: It's not if but when

Journalist Thompson presents clear picture of coming disaster and urges greater preparedness

By JACQUELINE WINDH   The Vancouver Sun     August 4, 2011


 Journalist and documentary filmmaker Jerry Thompson has been chasing the story of the Cascadia subduction zone, which lies off North America’s West Coast, and the possibility of a “megathrust” earthquake, for 30 years. In the introduction to Cascadia’s Fault, he notes that “scientists, civil engineers, and emergency planners know with certainty that it’s bound to happen here, but they’re having a devil of a time getting anyone to pay attention. This book, I hope, will change that.”

Cascadia’s Fault was going to press just as the magnitude 9 Tohoku Earthquake rocked Japan this March, sending a series of tsunami waves to Cascadia’s shores.

By the time those waves reached North America, much of their power had been sapped. Nevertheless, they caused damages estimated at over $50 million to coastal towns in California and Oregon, and killed one man. Although Canadian coastlines were spared any significant damages, local residents of towns such as Ucluelet, Tofino and Port Alberni reported strong currents and rapid sea-level fluctuations of a metre or more.

While this timing may seem bad luck for author Thompson, for it makes his detailed compendium and analysis of most of the planet’s recent large quakes instantly out-of-date, it is also fortuitous. If Thompson’s aim with this book was to draw attention to the risk of a large subduction-associated megaquake here in North America, the comparison of our situation with Japan’s can only help that.

Geologically, the Japanese scenario is a mirror-image of our geological setting here: a sometimes-locked subduction zone, where the Pacific tectonic plate moves in fits and starts beneath the thicker continental plate. Socially, the Japanese scenario is analogous to our own as well — directly above those subducting plates are modern cities sprinkled with mammoth structures of concrete and metal: highrises, industrial facilities, and highway overpasses.

The Cascadia subduction zone is an active fault that is 1,300 kilometres in length, extending from Northern California to northern Vancouver Island. When it finally slips — which could be in 200 years or it could be tonight — the destruction will be analogous to what happened in Japan, devastating a region 200 kilometres wide along the entire length of the fault, including the cities of Vancouver, Victoria, Seattle, Portland and Sacramento.

Although it is a valuable compendium of information, as a text the book suffers somewhat in its structure. Part detective story, part memoir and part popular science, the narrative is crafted as a thriller. The detective story — investigating whether the Cascadia subduction zone has the potential to generate magnitude 9 megaquakes — takes up the bulk of the text. Chapters flit around in time, jumping from the 1980s to the 1960s to the 2000s: describing other megaquakes that have occurred around the planet and assembling evidence from various scientific studies.

But a thriller loses much of its punch when we already know the answer to the mystery (in the text, the revelation that Cascadia’s fault is probably not harmless comes on page 204). And the memoir aspects of the story, chronicling the author’s interest in the subject, and his travels and interviews over the decades, come so few and far between that the jump to the first person can be jarring.

But Thompson excels when he explains the science. His methodical chronicling tells how each piece of the puzzle was uncovered — from investigations of cedar forests killed by saltwater flooding in Washington state, to GPS arrays that reveal the slow but steady compression of mountain ranges on Vancouver Island. Thompson presents the data that, together, provide a clear picture of the scale and magnitude of Cascadia’s coming earthquake and tsunami.

Whereas most of the book is devoted to piecing together the geological evidence, its final quarter addresses emergency planning. And this is a call for us to examine, especially here in Canada, what we are doing to prepare for it.

While American states, particularly California and Oregon, have detailed disaster plans and public awareness programs, British Columbia lags behind. Canada has no National Guard, and most of our active army units are either stationed east of the Rockies or deployed overseas. Damage to infrastructure: roads and railways and bridges, along with the potential scale of this disaster — how many communities will be affected — will cause delays of days or even weeks for rescue crews trying to provide assistance.

Thompson does a fine job of assembling the information about this coming event, literally presenting it on a platter to anyone who will listen. But, as one of the scientists he quotes says, “What the emergency response people do with that — it’s up to them.”

Jacqueline Windh is an author and photographer who holds a Ph.D. in Earth Sciences. She is based on Vancouver Island.
© Copyright (c) The Vancouver Sun