Megaquake watch: Northwest is under a lot of pressure right now
May 23, 2018, 2:06 PM
This map shows the first 10 days of ETS, color coded by time (blue early, red late). Photo: PNSN
(blue early, red late)
It’s that special time of year again, when Seattleites hear yet another warning about potential doom. While the notorious Cascadia megaquake always remains a vague threat, the risk of it actually happening is a little higher at the moment.
Why? According to the Pacific Northwest Seismic Network, we’re over two weeks into the annual episodic tremor and slip (ETS), which increases tectonic plate pressure along the Cascadia subduction zone. That zone stretches from northern California to Vancouver Island. The slip typically occurs every 14 months after the Juan de Fuca tectonic plate stops moving east, and begins to move west instead.
That reversal of crustal motion literally stresses out the Cascadia subduction zone and causes regular tremors.
RELATED: How to camp in your house during the great Cascadia earthquake
“We are now 10-plus days into this ETS and it seems to be developing similar to many of the previous events, particularly those from 2007 – 2011,” wrote PNSN professor Steve Malone in a recent blog post. “Over the past couple of days tremors first spread slightly to the north and then to the south.”
This news shouldn’t necessarily prompt any major changes in anyone’s day, like wearing runners instead of sandals, or grabbing your coffee to go. As with real estate, the seismic danger posed by ETS events is dependent on location. The threat potentially increases when it occurs down the slope of the seismogenic zone.
So the probability of an megaquake occurring is only slightly higher during a slip event. Since it was already reasonably high (17 to 20 percent in the next 50 years by some projections), there’s no need to spend any extra energy worrying about it.
Preparing for the great megaquake
But for those who enjoy worrying, this is as good an opportunity as any to work on an earthquake plan. Or perhaps a megaquake plan — which is pretty much the same plan. Safety experts recommend preparing under the assumption that local responders won’t be able to help for a few days. This can include plans for evacuation, communication with loved ones, food and water to last a few weeks, and maybe some good earthquake music.
Earthquake expert: We can’t predict or warn you about the ‘Big One’
Otherwise, we can only wait and see as the Juan de Fuca plate slides underneath the North America plate, until the parts that are locked together, unlock and spring apart, causing what’s being projected as a 9.0 earthquake with a side of tsunami.
“We expect this ETS to continue for at least another two to three weeks, spreading a bit farther south but quite a bit more to the north,” said Malone.
To nervously watch for the appearance of tremors, head here.
