By David Yamaguchi The North American Post
On December 15, the Discovery Channel will be showing an earthquake documentary titled “On the Brink of Disaster.” It reviews the 20-year project I participated in, which began when I was a freshly minted forester just out of the UW forestry school. Then, my first job involved working as a forestry consultant to US Geological Survey geologists who were trying to understand (a) Mount St. Helens, and later, (b) regional earthquake hazards from the moving coastal earth plates that are the source of the volcano’s angst.
Our thinking was that the regional geology is comparatively young while trees in affected mountain slopes and coastal forests are old. Thus, old trees must have recorded much of what the geologists were seeking. This is why they offered me the job. As a student, I had started making a name for myself as a specialist in reading tree rings.
Across the project period, my colleagues and I approached and resolved a series of logical questions. (1) Do large earthquakes happen in the Pacific Northwest? (2) If so, how often? (3) When was the last one? (4) How large was it? (5) When might the next similar one recur?
Northwest earthquake geologist Brian Atwater and I especially were on the trail of what has become known today as the “1700 Cascadia Earthquake.” The quest would bring us from the Washington coast to Alaska, Chile and Japan.
Readers with many annual rings might be thinking, hasn’t this story already been told in prior documentaries? (It has.) But the filmmakers’ perspective is that widespread interest remains in this now-classic Northwest tale that confirms Native legends. Moreover, it needs to be retold to each new generation for disaster preparation.
My viewpoint is that field science documentaries are much better today than a decade ago. Now they are aided by drone aerial photography, which helps capture the landscape settings of tree groves, for example.
For NAP readers, I would add that sometimes it helps in life to have been a kid who regularly attended Japanese school with my cousins. Our names commonly appeared quarterly in this paper, not as the best students, but as ones “with perfect attendance.”
Years later, Atwater and I would travel the Pacific coast of Japan together twice to examine Japanese brush-stroked records of unusual tsunami waves that flooded them from Tohoku (near Morioka) to Wakayama (Tanabe), a distance of 750 miles. The waves were not preceded by an earthquake felt in Japan.
In addition to studying the documents and their historical settings, the Japan field work also involved our interviewing elderly men and women in the streets of rural Tohoku.
I asked them, “Chiri tsunami no toki ni, koko de sunde imashita ka?…” (Were you living here at the time of the 1960 tsunami from Chile?…)
That earthquake had been a magnitude 9 event. Its destructive waves in Tohoku were the modern analogs of the 300-year-old ones that Atwater and I were chasing.
Further info: Brian Atwater & others, “The Orphan Tsunami of 1700,” 2nd ed., 2015 (full-text online & UW Press paperback, 144 pp.).
