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By Catherine Keys August 18. 2015 12:01AM Quake risk means LNG plant is a bad idea To appreciate the intricate details of the controversy surrounding the construction of a liquefied natural gas export terminal in Coos Bay, it is necessary to understand some basic geologic concepts and terminology. The oceans and continents of the Earth are gradually rearranged over time measured in epochs by the drift of huge slabs of the planet's mantle and crust known as tectonic plates. Where these plates, moving in opposite directions, meet, the region is subject to earthquakes. Where oceanic plates meet continental plates, the heavier oceanic plates dive under the lighter continental plates in a process referred to as "subduction." Subduction zones give rise to the most violent and most dangerous earthquakes known to science. And they are usually followed by tsunamis. The West Coast of North America, from Vancouver Island, B.C., to Cape Mendocino in northern California, has been shaped over the centuries by a 700-mile long subduction zone known as the Cascadia Subduction Zone (CSZ). Here, three oceanic plates are subducting under the North American plate, the largest of which is the Juan de Fuca plate. Normally, these plates move in opposite directions at a rate of about 1.6 inches per year, creating small-scale earthquakes as the plates grind against each other. When the plates resist this convergent motion, however, they can lock up, causing pressure to build up within the plates and causing the continental plate to bulge upwards as it tries to move over the oceanic plates. When the plates break loose, they cause big earthquakes.  Right now, and for more than 300 years, the Juan de Fuca plate has been locked up with the North American plate. When these two plates break apart, and it is a certainty they will, the Cascadia region will be subject to violent earthquakes and tsunamis. If only the southern portion of the CSZ gives way, the resulting earthquake will measure between magnitude 8.0 and 8.6. If the entire CSZ breaks up at once, an event seismologists call a "full-margin rupture," the earthquake will measure between 8.7 and 9.2. This "full rip" earthquake will re-arrange the entire West Coast of North America. The ensuing tsunami will inundate the coast for 10 miles inland. This 700-mile wall of water will be between 20 and 100 feet tall and will include boats, vehicles, rocks, chunks of concrete, piers — and people — and will strike in as little as 15 minutes after the first earthquake shock. After the main earthquake, the tsunami and the inevitable aftershocks, the entire region will be unrecognizable. If such a full rip occurs, the region will have suffered the worst natural disaster in the history of North America. According to earth scientist Chris Goldfinger, the odds of the CSZ generating a magnitude 8 earthquake in the next 50 years are one in three. The odds of a full rip: one in 10. The final consideration in evaluating the issue of building the LNG terminal in the known CSZ and tsunami inundation zone that is Coos Bay is the frequency of magnitude 9 events. The last full rip occurred in January of 1700, 315 years ago. Geologic evidence indicates that such large-scale earthquakes have occurred at least seven times in the past 3,500 years. This computes to an average interval of 500 years. However, this kind of regularity is not evidenced in the geologic record. Instead, the time spans between magnitude 9 events have been as little as 200 years and as long as 1,000 years. Hence, it is beyond argument that we are within the risk zone of another major CSZ earthquake. It could happen tomorrow, or it could happen two centuries in the future. When we as a society think about our future, we should think deeply about what we know the earth has in store for us. The rhythms and cycles of our planet are much slower than our short life cycles. The brevity of our lives breeds a sort of temporal parochialism; an indifference to the planetary gears that turn so much more slowly than our own. At some point, geologic time will catch up with our human perception of time, and our whole world will change. I encourage my fellow citizens and our decision-makers to think in terms of our grandchildren's grandchildren, and reject the LNG pipeline and export terminal projects as being inconsistent with the overarching best interests of our population. Catherine Keys lives in Medford. http://www.mailtribune.com/article/20150818/OPINION/150819722 © 2015 Copyright © 1995-2011 Crain Communications Inc. All Rights Reserved. Terms of Use Privacy Statement -->