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Eric Dittmer

Act Locally: High chance of 'Big One; in next 50 years

A sole 1950s frosted-glass lamp sits by the front door of my Ashland home. In a visceral childhood memory, its matching mate tumbles from my parents’ mantelpiece, sails mere inches past my father’s head, and shatters on an undulating living room carpet in the largest earthquake (magnitude 4.5) to hit the Portland area during my youth.

While this was shocking at the time, the moderate magnitude of that temblor pales by comparison to the size of 40 major quakes that shaped Oregon’s topography over the past 10,000 years. Just as the earth’s sedimentary layers reveal the trajectory of long-term planetary climate change (see previous installment of Act Locally, dailytidings.com/lifestyle/act-locally), a study of the sediment left behind by past tsunamis speaks to historical ruptures along the Cascadia Subduction Zone fault in regularly repeated patterns. An analysis of the cyclical nature of tsunami residue on the coast has led geologists, such as Southern Oregon University Professor Emeritus Eric Dittmer, to warn Oregonians that the next big quake is imminent.

Born and educated in the Monterey Bay area, Prof. Dittmer moved his family to Medford in 1979. Until he began teaching Geology and Environmental Studies at SOU in 1992, his professional focus was on monitoring air and water quality, and studying other environmental issues as part of various governmental agencies. Once at SOU, Prof. Dittmer became aware of the recent earthquake studies by Northwest researchers, primarily from Oregon State University.

Clued in by tales from indigenous people, as well as “ghost forests” along coastal rivers (trees that had become defoliated when flooded by sea water), geologists had examined the contents of sedimentary layers in salt marshes consistent with a forceful tsunami along the Oregon coast. Japanese documents describing a devastating tsunami that appeared without a concomitant local earthquake on Jan. 26, 1700, enabled scientists to assign an exact date to the previous Cascadian rupture. Noting the regularity of the appearance of similar materials in deeper layers of sediment, geologists concluded that major quakes occurred between every 250-400 years. Citing Chris Goldfinger of OSU, Prof. Dittmer states: Oregon “has a one-in-three chance of a magnitude 8-9 quake within the next 50 years.”

Since retiring from his university position in 2011, Prof. Dittmer has been lecturing the public both about this pending danger, as well as actions Oregonians can take in preparation. He warns: “Climate change is a worldwide issue, while the Cascadia Subduction Zone is local to the Pacific Northwest The financial impact of climate change has certainly been felt here; wildfires and poor air quality have led to a reduction in tourism, with cancellations of Shakespeare performances and rafting trips, and a reduced ski season at Mt. Ashland. Those are tangible now. Whereas earthquakes may be something people are concerned about, but the immediacy of the risk is harder to show (But if you are preparing for one cataclysmic event) there’s no reason why you can’t prepare for both.”

When the Cascadia fault “unzips,” the greater the portion of its 700-mile length that ruptures, the larger the magnitude of the resultant quake, and the longer the land will shake (roughly five minutes). Prof. Dittmer predicts that this forceful, prolonged undulating is sure to cause serious destruction to much of our infrastructure. Water and electricity delivery will be disrupted for days, maybe months. Phone service and Wi-Fi will be out. Bridges and overpasses will collapse, impeding transportation.

Initially, this means emergency services will not be able to reach many folks in trouble; but, over time, all types of necessary goods — food, gasoline, medicine, first aid supplies, etc. — may not be available for weeks. With cash machines non-operative, active currency “will not be credit cards; it will be toilet paper.”

Prof. Dittmer has a long list of recommendations. Readers can find out more about these during a four-session OLLI course, Earthquake Preparedness in the Pacific Northwest, he will offer from 11 a.m. to 12:30 p.m. Thursdays, Jan. 17 through Feb. 7, in Medford (inside.sou.edu/assets/olli/docs/Winter-2019-catalog.pdf).

One action he suggests readers take is to view Oregon Public Broadcasting’s “Oregon Unprepared,” a series of several earthquake videos detailing many of the above issues (www.opb.org/news/series/unprepared).

My recommendation is for readers to keep on hand several (otherwise ecologically unsound) plastic products in case of emergency. Please don’t drink plastic bottled water on a regular basis, but please do store several plastic bottles of purified water in every available location — kitchen, bathroom, bedroom, outside deck, car, etc. (You don’t know where you’ll be when the Big One hits.) Also, keep on hand heavy-duty plastic trash bags and a bucket; if worst comes to worst, these can serve as a toilet.

Both of us recommend that readers be sure to stash away not only sufficient nourishing canned goods, but some comfort foods as well. Neither Eric nor I relish the idea of a day without chocolate.

Ashland resident, author and anthropologist Nina Egert has been a lay environmentalist since the early 1970s. Act Locally appears the first and third Mondays of the month in the Tidings.

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