Recommend
5 
 Thumb up
 Hide
7 Posts

BoardGameGeek» Forums » Everything Else » Chit Chat

Subject: The big one on the West Coast--not in California! rss

Your Tags: Add tags
Popular Tags: [View All]
Walt
United States
Orange County
California
flag msg tools
Before terraforming Mars, Surviving Mars is required: Paradox Interactive; Steam.
badge
Please contact me about board gaming in Orange County.
Avatar
mbmbmbmbmb
The Economist has an interesting article on the probabilities of quakes on the West Coast of the US, part of the "Pacific Ring of Fire". The summary version is that the San Andreas isn't that dangerous because it's a slip-strike (sideways-sliding) fault, with a large, smoothly sliding area in between LA and SF. So, while the SA could give a 8.3 if the whole length went, this isn't going to happen because the two ends have the big quakes, but not the middle.

The real problem is the shallow Cascadia subduction fault (one plate sliding under another, like the fault that generated the Japanese earthquake). Cascadia is capable of a 9+ earthquake and for the same reasons as the Japanese quake, is likely to generate a tsunami of as much as 30 meters / 100 feet. The article suggests a 1/3 chance of this happening in the next 50 years.

http://www.economist.com/blogs/babbage/2011/03/megaquakes

USGS has some information, but it's rather turgid. These look like places to start:

http://earthquake.usgs.gov/regional/pacnw/
http://www.pnsn.org/HAZARDS/CASCADIA/cascadia_zone.html

2 
 Thumb up
 tip
 Hide
  • [+] Dice rolls
Billy McBoatface
United States
Lexington
Massachusetts
flag msg tools
KGS is the #1 web site for playing go over the internet. Visit now!
badge
Yes, I really am that awesome.
Avatar
mbmbmbmbmb
Portland is (as you can see) right in the hot spot of this problem. It comes up in newspaper articles sometimes.

Our school district had a study done to examine earthquake safety for every school. When the big quake hits, my daughters' school has a 100% chance of collapsing completely. I really, really hope that the bond measure (which will retrofit the school for earthqake safety, among other things) passes. Unfortunately the bond measure has problems that makes it unlikely to pass, but if it fails and then a few years from now the quake hits and every student dies under a pile of bricks... soblue soblue soblue
2 
 Thumb up
 tip
 Hide
  • [+] Dice rolls
Walt
United States
Orange County
California
flag msg tools
Before terraforming Mars, Surviving Mars is required: Paradox Interactive; Steam.
badge
Please contact me about board gaming in Orange County.
Avatar
mbmbmbmbmb
Good luck with the bond. Please don't tell me you literally build with bricks in an earthquake zone!
1 
 Thumb up
 tip
 Hide
  • [+] Dice rolls
Billy McBoatface
United States
Lexington
Massachusetts
flag msg tools
KGS is the #1 web site for playing go over the internet. Visit now!
badge
Yes, I really am that awesome.
Avatar
mbmbmbmbmb
Tall_Walt wrote:
Good luck with the bond. Please don't tell me you literally build with bricks in an earthquake zone!
Yup. The school is solid brick. It was only relatively recent that Oregon, Washington, and BC were considered at risk for big earthquakes. They only come once every few hundred years, the last was 1700, before Lewis and Clark explored the area. Apparently the Indians have stories of huge earthquakes, but not much attention was paid to them as the Westerners arrived and started building their cities.
5 
 Thumb up
 tip
 Hide
  • [+] Dice rolls
Walt
United States
Orange County
California
flag msg tools
Before terraforming Mars, Surviving Mars is required: Paradox Interactive; Steam.
badge
Please contact me about board gaming in Orange County.
Avatar
mbmbmbmbmb
Ouch. You don't need to retrofit. You need to tear it down and rebuild earthquake-safe.
6 
 Thumb up
 tip
 Hide
  • [+] Dice rolls
Brian Morris
United States
Raytown
Missouri
flag msg tools
2nd, 6th and 7th Wisconsin, 19th Indiana, 24th Michigan
badge
24th Michigan Monument Gettysburg Pa
Avatar
mbmbmbmbmb
Subduction faults generally are more dangerous than side slip faults. Because (a) They have larger quakes and (b) They tend to be in the ocean and thus cause tsunamis. In the case of Japan and Indonesia the deaths from tsunamis was far greater than from the quakes themselves. In fact in Japan the buildings held up extremely well to the quake itself.

The subduction zone off the coast of Washington and Oregon is exactly the same type that ruptured in Japan and Indonesia. In fact it had a 9.0 quake about 700 years ago that caused a tsunami to strike Japan which was called the orphan tsunami by the Japanese at the time because they were use to tsunamis but this one showed up with no earthquake from their perspective.

I still would not discount the San Andreas mind you. It still can produce 8.0 quakes and do so only a few miles from San Francisco as in 1906. Research is now showing that the strain along the San Andreas that ruptured in 1906 has about the same strain now as it did back then. In 1906 the rupture resulted in the San Andreas slipping 10 feet. The stress in the San Andreas builds up at 1 inch per year or about a foot every 10 years. It's been 105 years since the great 1906 earthquake. The math is easy to do.
4 
 Thumb up
 tip
 Hide
  • [+] Dice rolls
Walt
United States
Orange County
California
flag msg tools
Before terraforming Mars, Surviving Mars is required: Paradox Interactive; Steam.
badge
Please contact me about board gaming in Orange County.
Avatar
mbmbmbmbmb
mrbeankc wrote:
...it had a 9.0 quake about 700 years ago that caused a tsunami to strike Japan which was called the orphan tsunami...

About 300 years: between 9pm and 10pm January 26, 1700, based on the arrival of the tsunami in Japan.
3 
 Thumb up
 tip
 Hide
  • [+] Dice rolls
Front Page | Welcome | Contact | Privacy Policy | Terms of Service | Advertise | Support BGG | Feeds RSS
Geekdo, BoardGameGeek, the Geekdo logo, and the BoardGameGeek logo are trademarks of BoardGameGeek, LLC.