I’m slowly getting the house ready for the move to Oregon, but I’m not sure Oregon’s getting itself ready for me – disturbing news from the west coast concerns mysterious swarms of earthquakes off the coast of Oregon. There have been more than 600 quakes over the past 10 days, according to the Associated Press. The biggest was a magnitude 5.4, and two others were more than magnitude 5.0.
This shouldn’t be too surprising, as western Oregon overlies a subduction zone, where continental crust of the North American plate is overriding oceanic crust of the Juan de Fuca plate. As the oceanic plate sinks and melts due to the earth’s heat, the magma rises to the surface in the form of the Cascade volcanoes (such as Mt. Hood and Mt. Saint Helens). Since the Juan de Fuca plate is also sliding past the adjacent Pacific plate as it heads toward its continental subduction zone, offshore earthquakes are not uncommon at the transform faults marking the plate boundaries.
This is basic, first-year geology. What’s interesting about the recent swarm of earthquakes, however, is that according to the AP they have a pattern, magnitude and frequency more commonly associated with volcanoes, not transform faults. And according to all the accepted geologic models of the area, volcanoes should form beneath the overriding continental crust, but beneath the offshore oceanic crust. “Scientists don’t know exactly what the earthquakes mean, but they could be the result of molten rock rumbling away from the recognized earthquake fault zones off Oregon,” the AP reports.
According to the USGS Earthquake Hazards Program, there was a magnitude 5.2 early Saturday morning, as well as a 5.0 Thursday evening and a 3.8 Tuesday night. But all of these were close to the Juan de Fuca-Pacific plate margin, exactly where you’d expect to find transform-fault quakes.
But according to a news release on the Oregon State University web site, a swarm of hundreds of quakes have in fact been detected off shore in the last 10 days. OSU marine geologist Robert Dziak calls the earthquake swarm unique, because it is occurring near the middle of the plate, away from the major, regional tectonic boundaries.
My concern is not about devastation of Portland by one (or many) of these quakes – if I wanted to worry about an earthquake in Portland, I’d worry about the Portland Hills fault running through downtown Portland. I’m also not worried about a new offshore volcano popping up off the Oregon coast – that would actually be kind of cool and Portland is used to being near active volcanoes, like Saint Helens and Hood.
What worries me are tsunamis generated by this seismic activity. Portland is at very low altitude - only a few tens of feet above sea level – and although it is protected from coastal storms by the Coast Range, that barrier is breached by the Columbia River. My nightmare scenario is a huge tidal wave crossing the open ocean, crashing into the Coastal Range and rolling up the Columbia valley. The height of the wave becomes amplified by the narrow valley walls, until the water meets the confluence of the Columbia and Willamette Rivers just past the Coast Range, where the wave collapses laterally and sweeps the short distance up the Willamette to Portland, quickly inundating the city beneath tens of feet of water. “Portland is drowning, and I live by the river,” to paraphrase The Clash.
But meanwhile, back here in the alpine heights of Atlanta, GA, I’ve still been getting the house ready for the move. Friday, I met with a realtor – the same one who represented me when buying this house – and we talked about pricing. I’ve only lived here a couple of years and so still owe the bank a substantial share of the value, and on top of that there are realtor and closing costs to consider. And since we’re apparently in the worst real-estate market of the last 20 or so years, a fact confirmed to me by the agent, I was concerned if I could still get a price for the house sufficient to cover my payout, the realtor commissions, and other costs without having to bring my own cash to closing.
But the realtor, while still encouraging me to price the house as low as possible so as to compete in this buyers' market, still agreed that I could get a price high enough to walk away with anywhere from $75 to $100k in my pocket.
So, encouraged by this news, Saturday was a major house cleaning, getting rid of clutter, including the big dysfunctional television that’s been sitting in my dining room for two years now. I also got rid of a desk in the spare bedroom, as well as all of the so-called e-waste I’ve accumulated over the past decade or so – three separate computers and all of their associated peripherals, including one dead flat-screen monitor.
I’m something of a pack rat and it stung a little to hand the computers over to the junkman I called to haul all the stuff away. Who knows – maybe I could have salvaged some RAM from one of the computers, or resurrected one or more of them. But once they were gone, it actually felt good to have divested myself of what was after all just junk. And as the junk truck rode off down the road with my television, computers and old desk, I sighed with relief and then inhaled my first sweet breath of renunciation.
Post Script (9:50 pm, April 13): A magnitude 4.0 earthquake occured off the Oregon coast at 1:44 pm Pacific time.