3 ms·

"The Pacific Northwest sits squarely within the Ring of Fire. Off its coast, an oceanic plate is slipping beneath a continental one. Inland, the Cascade volcano

by soperj 11y ago

"The Pacific Northwest sits squarely within the Ring of Fire. Off its coast, an oceanic plate is slipping beneath a continental one. Inland, the Cascade volcanoes mark the line where, far below, the Juan de Fuca plate is heating up and melting everything above it. In other words, the Cascadia subduction zone has, as Goldfinger put it, “all the right anatomical parts.” Yet not once in recorded history has it caused a major earthquake—or, for that matter, any quake to speak of. By contrast, other subduction zones produce major earthquakes occasionally and minor ones all the time: magnitude 5.0, magnitude 4.0, magnitude why are the neighbors moving their sofa at midnight. You can scarcely spend a week in Japan without feeling this sort of earthquake. You can spend a lifetime in many parts of the Northwest—several, in fact, if you had them to spend—and not feel so much as a quiver." This is total crap. There was a 6.8 magnitude earthquake in Seattle in 2001.

3JPLW 11y ago
I wonder if they discounted this because it was (as wikipedia lists it) an "intraslab" earthquake. I'm not a seismologist, but that reads to me like it wasn't an earthquake from the fault line directly, but rather a secondary artifact of the subduction zone. I agree this is very misleading, but as they tell it through the historical lens, this earthquake also hadn't happened before they realized there could be earthquakes or that they could be big.
- matheweis 11y ago
  Wikipedia (sorry), has a nice diagram that shows the different categories; the "crustal" and " deep" earthquakes being different from the subduction zone earthquakes that this article is specifically about: https://en.wikipedia.org/wiki/Cascadia_subduction_zone#/media/File:Cascadia_earthquake_sources.png https://en.wikipedia.org/wiki/Cascadia_subduction_zone#/medi...
jameshart 11y ago
They are contrasting what they describe as weekly small quakes in Japan with long periods of inactivity in the Pacific Northwest. A significant quake in one city in the region 14 years ago doesn't invalidate the claim that you could spend a significant time in the northwest without feeling a tremor.
- jflatow 11y ago
  But the article says you could spend many lifetimes.
  - kenbellows 11y ago
    Maybe you could, as long as those lifetimes don't happen to contain that one 6.8 event. I don't think the point was to look back several lifetimes from right now, but rather to talk about the overall frequency of earthquakes in recorded history. (Caveat: I know nothing about the seismic history of the Pacific NW, this is just how i read the statement.)
- soperj 11y ago
  It's certainly not the only earthquake I've felt in the 15 years that I've lived here, just the biggest. Which is definitely different from not feeling a quiver in many lifetimes.
  - chrisfosterelli 11y ago
    I live north east of Vancouver and have lived my whole life without even a shake. Most of my friends (from all over) have never felt one either. He didn't say "everywhere", just "many places".
    - soperj 11y ago
      Were you not there in 2001? Because that was pretty hard to miss.
      - goodcanadian 11y ago
        I was in Vancouver for that one. I didn't feel a thing. There seemed to be a fairly even mix among my friends depending on where they were. Some felt it quite strongly. Some didn't notice it.
Sleaker 11y ago
I agree. There are regularly 4.0-5.5 earthquakes along the oregon coast, and the seismologists that report on these say that they are a result of the Cascadia Subduction... I was interested until I got to this point as the local reports on earthquakes are counter to what the article suggest. I mean there was even a 4.2 in Springfield, OR within a week. just check the US geological data. Claims seem dubious without having a full text report of what the difference between the types of quakes are, and difference in areas as related to 'the big one' without this, anyone looking at past earthquake data will say this guy is nuts, because we do have regular quakes in the Northwest, especially coastal.
- davidw 11y ago
  > I mean there was even a 4.2 in Springfield, OR within a week I felt that one - I was over in Eugene for the weekend of the 4th, and was... uh... seated, when it felt like something slammed into the house. Not much shaking, just one short, sharp impact.
saintgimp 11y ago
I've lived in Seattle for 20 years and the only earthquake I've ever actually felt here was the Nisqually quake in 2001. Contrast that with some parts of Japan where you feel quakes on a monthly basis or more.
cossatot 11y ago
As 3JPLW mentioned, the 2001 Nisqually event was in the subducting Juan de Fuca slab, not on the plate interface, and was quite deep (52 km). The Cascadia plate interface itself does have quite regular 'slow earthquakes'[1] at the lower edge of the locked zone, where M~6 earthquakes occur over about a week and a half, and don't produce much shaking. We just found out about them by watching patterns in GPS data from fixed locations. Regardless, Goldfinger is still correct on all the statements that you've quoted. In addition to the scientific content, it still is possible to spend several lifetimes in the PNW (which does extend beyond King County) in between the 1700 event and the 2001 event. Granted, there was the 1872 event near Lake Chelan [2], which was the biggest PNW quake since 1700, but still... there were multiple generations of people born in between 1872 and 2001. [1]: http://www.geodesy.cwu.edu/instruments/tilt/explanation_ETS.html http://www.geodesy.cwu.edu/instruments/tilt/explanation_ETS.... [2]: http://www.seattletimes.com/seattle-news/scientists-may-be-cracking-mystery-of-big-1872-earthquake/ http://www.seattletimes.com/seattle-news/scientists-may-be-c...

by soperj 11y ago

3JPLW 11y ago

I wonder if they discounted this because it was (as wikipedia lists it) an "intraslab" earthquake. I'm not a seismologist, but that reads to me like it wasn't an earthquake from the fault line directly, but rather a secondary artifact of the subduction zone. I agree this is very misleading, but as they tell it through the historical lens, this earthquake also hadn't happened before they realized there could be earthquakes or that they could be big.

matheweis 11y ago
Wikipedia (sorry), has a nice diagram that shows the different categories; the "crustal" and " deep" earthquakes being different from the subduction zone earthquakes that this article is specifically about: https://en.wikipedia.org/wiki/Cascadia_subduction_zone#/media/File:Cascadia_earthquake_sources.png https://en.wikipedia.org/wiki/Cascadia_subduction_zone#/medi...

jameshart 11y ago

They are contrasting what they describe as weekly small quakes in Japan with long periods of inactivity in the Pacific Northwest. A significant quake in one city in the region 14 years ago doesn't invalidate the claim that you could spend a significant time in the northwest without feeling a tremor.

jflatow 11y ago
But the article says you could spend many lifetimes.
- kenbellows 11y ago
  Maybe you could, as long as those lifetimes don't happen to contain that one 6.8 event. I don't think the point was to look back several lifetimes from right now, but rather to talk about the overall frequency of earthquakes in recorded history. (Caveat: I know nothing about the seismic history of the Pacific NW, this is just how i read the statement.)
soperj 11y ago
It's certainly not the only earthquake I've felt in the 15 years that I've lived here, just the biggest. Which is definitely different from not feeling a quiver in many lifetimes.
- chrisfosterelli 11y ago
  I live north east of Vancouver and have lived my whole life without even a shake. Most of my friends (from all over) have never felt one either. He didn't say "everywhere", just "many places".
  - soperj 11y ago
    Were you not there in 2001? Because that was pretty hard to miss.
    - goodcanadian 11y ago
      I was in Vancouver for that one. I didn't feel a thing. There seemed to be a fairly even mix among my friends depending on where they were. Some felt it quite strongly. Some didn't notice it.

Sleaker 11y ago

I agree. There are regularly 4.0-5.5 earthquakes along the oregon coast, and the seismologists that report on these say that they are a result of the Cascadia Subduction... I was interested until I got to this point as the local reports on earthquakes are counter to what the article suggest. I mean there was even a 4.2 in Springfield, OR within a week. just check the US geological data. Claims seem dubious without having a full text report of what the difference between the types of quakes are, and difference in areas as related to 'the big one' without this, anyone looking at past earthquake data will say this guy is nuts, because we do have regular quakes in the Northwest, especially coastal.

davidw 11y ago
> I mean there was even a 4.2 in Springfield, OR within a week I felt that one - I was over in Eugene for the weekend of the 4th, and was... uh... seated, when it felt like something slammed into the house. Not much shaking, just one short, sharp impact.

saintgimp 11y ago

I've lived in Seattle for 20 years and the only earthquake I've ever actually felt here was the Nisqually quake in 2001. Contrast that with some parts of Japan where you feel quakes on a monthly basis or more.

cossatot 11y ago

As 3JPLW mentioned, the 2001 Nisqually event was in the subducting Juan de Fuca slab, not on the plate interface, and was quite deep (52 km). The Cascadia plate interface itself does have quite regular 'slow earthquakes'[1] at the lower edge of the locked zone, where M~6 earthquakes occur over about a week and a half, and don't produce much shaking. We just found out about them by watching patterns in GPS data from fixed locations. Regardless, Goldfinger is still correct on all the statements that you've quoted. In addition to the scientific content, it still is possible to spend several lifetimes in the PNW (which does extend beyond King County) in between the 1700 event and the 2001 event. Granted, there was the 1872 event near Lake Chelan [2], which was the biggest PNW quake since 1700, but still... there were multiple generations of people born in between 1872 and 2001. [1]: http://www.geodesy.cwu.edu/instruments/tilt/explanation_ETS.html http://www.geodesy.cwu.edu/instruments/tilt/explanation_ETS.... [2]: http://www.seattletimes.com/seattle-news/scientists-may-be-cracking-mystery-of-big-1872-earthquake/ http://www.seattletimes.com/seattle-news/scientists-may-be-c...