Tag Archives: natural disasters

Seattle and Portland Are 72 Years Overdue For A Horrific Earthquake

Yes, you thought right: there hasn’t been a major earthquake in the Pacific Northwest since it was discovered by Western civilization. There have only been seven recorded in the region, averaging 6.3 in magnitude and killing 14 people total. And Seattle is the least likely metropolitan area in the US to have a natural disaster of any kind.

In fact, until 50 years ago, no one thought that earthquakes were much of an issue at all, in that area. But then, tectonic plate theory became mainstream and scientists noted that earthquakes and volcanoes were prevalent all around the so-called Ring of Fire: New Zealand, Indonesia, Japan, Alaska, California, Mexico and Chile. Notice how we skipped right over the Pacific Northwest: the scientists noticed that too.

plate tectonics

The world’s tectonic plates. In the Pacific Northwest, the Juan de Fuca plate goes under the North American plate.

 

A very interesting article in The New Yorker tells us that these scientists then started drilling into the ocean floor off the coast of Washington state and found out that they could tell, from the stratification of the earth, when and how much land from the continent rushed into the sea — meaning, an earthquake had occurred, and how big it was. They went back 10,000 years and counted 41 major earthquakes, which means one happens every 243 years, on average. We know it’s been at least 210 years since there’s been one in that region, since Lewis and Clark went there in 1805. But how long has it been really?

Besides the ocean floor evidence for the year, we actually have some much cooler, and much more accurate data.  There’s a “ghost forest” near the beach in Washington State, by the Copalis River. It’s called that because it consists of a bunch of dead trees standing in sea water. The theory had been that sea water got into the forest and killed off the trees but, in the late 1980s, two scientists figured out that they actually all died at the same time, in the winter of 1699-1700. So, due to that sudden onset, they theorized that an earthquake actually plunged the forest about six feet into the sea.

Copalis ghost forest

Copalis ghost forest

That’s pretty cool on its own, but then in 1996, they got historical confirmation: the Japanese have been keeping track of tsunamis for over 1400 years, and they knew that earthquakes caused them. But there was one “orphan” tsunami for which they felt no preceding earthquake: it happened on January 27th, 1700, and we now know that the reason they didn’t feel the parent is because the epicenter was so far away, off the edge of the Pacific Northwest. Ten hours after it shook, the tsunami it created had crossed the Pacific and hit Japan. It also turns out that the Native Americans of the region also have stories about entire tribes being wiped out long ago by the earth sinking into the sea, and canoes being flung into trees. It would’ve been the seventh strongest earthquake known to history.

So there you have it: the last earthquake to hit Seattle happened about a hundred years before Lewis and Clark, and 315 years before now. Subtract the average of 243 years from that, and you get an uncomfortable 72 years of the region being overdue for a big one. The most recent deadly quake the US had, was a 6.9 magnitude one near San Francisco, in 1989: it killed 63 people. The one that destroyed San Francisco in 1906 was 7.8 and killed 3,000 people — the most of any earthquake to hit the country. The one that hit Japan in 2011 was 9.0 and killed 16,000 people. It was the strongest one that country, which gets weekly earthquakes, had ever seen and the fourth strongest known to man. The one coming to Seattle could register 9.2.

Earthquake magnitudes are logarithmic, so a 7.8 earthquake is 8x stronger than a 6.9 one, and a 9.0 earthquake is 16x stronger than the 7.8 one. To find out how much stronger one earthquake is than another, take 10 to the power of the difference between them; for example: 10**(9.2-6.9) = 199.53. This means that the one coming to Seattle could be 200x stronger than the 1989 San Francisco earthquake. (By the way, did you know the Richter scale has been obsolete since the 1970s? The above, and generally all earthquake measurements, are actually stated in the Moment Magnitude scale.)

And to be clear, this is not fringe science: FEMA officially believes that there’s a 37% chance of an earthquake with magnitude 8.0 to 8.6 hitting the Pacific Northwest in the next 50 years; a 10-15% chance it will be in the 8.7 to 9.2 range. Because the area is horrendously ill-prepared for an earthquake, it will kill 13,000 people, destroy the local economy (including Amazon and Microsoft headquarters) and take almost two years to repair the infrastructure.

However, all of this might actually not happen until after the year 2160: before the earthquake in 1700, the previous two were in 1310 and 810, which makes 390 and 500 years between them. In fact, the average period between the last five earthquakes in the area was 460 years: almost twice the length of the 10,000 year average. Maybe they’ve just slowed down over the past couple of millenia, or maybe we’re overdue for quicker ones. In any case, move over San Andreas Fault: the Cascadia Subduction Zone is the new thing to fear.

See also:

via The New Yorker

The Waffle House Index

People come up with some very elegant and down-to-earth indicators of the state of complex systems. The most widely known is probably the Big Mac Index, which has been around for a couple of decades and shows the price of Big Macs in different countries as a way to gauge their purchasing power. But there are others, like the Men’s Underwear Index (men buy less underwear in economic downturns) and the Hemline Index (the length of women’s skirts varies with economic health; better economy = shorter skirts). And according to the Wall Street Journal, FEMA uses the Waffle House Index to tell how badly damaged an area is after a natural disaster: if the Waffle House is closed somewhere, that means it’s serious.

They assign stoplight levels to areas normally served by a Waffle House: green means it’s open and serving a full menu, so there’s little damage; yellow means it’s open, but serving a limited menu, which means they’re running off a generator or gas grill, which in turn means there are significant infrastructure issues with either the power or food supply; and red means they’re closed, which is like DEFCON 1 for FEMA. The reason the agency uses this index is two-fold:

  • The Waffle House is all over the South, which gets the brunt of America’s natural disasters (because that’s how God shows his love: through tribulation)
  • The company has a policy of keeping stores open as much as possible, and if they have to close, to reopen as soon as possible

That policy is apparently a marketing ploy, because it’s not an instant money maker: if you’re the only place in town that serves food to hungry, battered people, they’ll remember that during the good times. So they scramble to get generators and gas and ice to stores that have been damaged, and can generally be the only open restaurant in a devastated area. Along with Walmart, Lowe’s and Home Depot, Waffle House is at the top of the list of companies with a good history of disaster response. When Hurricane Irene hit the mid-Atlantic, 22 Waffle Houses lost power, and all but one were back in business after 3 days.

From The Wall Street Journal, via Gizmodo

Map Showing Likelihood of Natural Disaster

The New York Times made a map that shows how likely different places across the US are to get a natural disaster of the tornado/hurricane/earthquake/drought/flood/hail variety. Here’s the skinny:

  • Of the big cities, Seattle gets the least disasters and Dallas gets the most
  • In general, Washington and Oregon are the best places to live if you want to avoid natural disasters — but not if you want to avoid hippies.
  • The Deep South (Texas, Alabama, Louisiana) is the worst place to live — but we already knew that.
  • Most of the Midwest and South are tornado-prone, and especially Oklahoma.
  • The entire Gulf and Atlantic coastlines are hurricane-prone, but especially the Atlantic coast from mid-Florida up to Virginia.
  • A good portion of the country is earthquake-prone: most of the Northeast, parts of the South and Midwest and almost all of the West, but especially the entire Pacific coastline.

 

From The New York Times via Lifehacker