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Old 10-23-2008, 05:03 PM
 
Location: On the Great South Bay
7,130 posts, read 9,898,127 times
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Quote:
Originally Posted by happ View Post
18Montclair
Thanks for introducing this fascinating discussion though I must admit to feeling a little uncomfortable contemplating a massive earthquake in the Bay Area

Widowmaker
Would the resulting tidal wave\ tsunami be worst for California or out in the Pacific [ie. Hawaii\ Alaska\ Japan]?
18Montclair I rated you postively for doing all those maps and charts but I am not sure if what I did registered because I am new. Anyway good job!

Regarding Tsunamis I saw some Discovery program that mentioned if a big chunk of the island of Hawaii ever slid into the Pacific (and the ocean is very deep there) there would be huge Mega-Tsunamis hitting large areas of North America, South America, and Asia. But I think we must remember the chances of these things happening while we are alive is very small.
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Old 10-23-2008, 05:45 PM
 
Location: Rural Northern California
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Quote:
Originally Posted by LINative View Post
Regarding Tsunamis I saw some Discovery program that mentioned if a big chunk of the island of Hawaii ever slid into the Pacific (and the ocean is very deep there) there would be huge Mega-Tsunamis hitting large areas of North America, South America, and Asia. But I think we must remember the chances of these things happening while we are alive is very small.

Yeah, there's a lot of debate about that. The other primarily cited 'megatsunami' threat is from a collapse of the Cumbre Vieja volcano on Isla de La Palma in the Canary Islands (which could possibly send a tsunami to the Atlantic Seabord), with some models predicting that wave heights could be on the order of 80-100 feet at landfall. There is, however, no record of an ocean-crossing tsunami ever having been formed in this manner, and many scientist doubt very much that it is even possible.

Most historical major (ocean crossing) tsunamis were formed when the over-riding plate in a subduction zone 'sprang back' to its original position as the subducting plate snapped free and slid underneath. When this happens, the water that was on top of the plate is suddenly several metres (or more) above sea level, propagating huge waves in all directions away from the event. Since the length of slip in a 'megathrust' earthquake is so large (hundreds or thousands of kilometres), the amount of water moved is tremendous. In even the largest landslide events, it's difficult to imagine water displacement on that magnitude. Local wave heights would be extreme, but many scientist think that these types of tsunamis would lack the ability to cross large distances, and would dissipate rather quickly.

Edit: Excellent 25 second video showing how a subduction zone creates a tsunami:
http://www.youtube.com/watch?v=9qXN8afIVEI

Though, if you're interested in things like that, wikipedia has several articles that go into much greater detail than I have.
Wiki Links:
Tsunami
Megathrust Earthquake
Hilina Slump (A probable location for a great Hawaiian landslide event)
Cumbre Vieja (Isla de La Palma landslide threat)
Cascadia Subduction Zone
Seattle Fault (The fault that I believe ScranBarre was referencing)
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Old 10-23-2008, 06:40 PM
 
6,954 posts, read 14,084,889 times
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Not to ruin the thread, but I think the Newport-Inglewood Fault is more dangerous.

NEWPORT-INGLEWOOD FAULT ZONE (http://www.data.scec.org/fault_index/newping.html - broken link)

According to that site, the last major quake from it was in 1933 and if it causes another quake now, it could be from 6.0-7.4. This would be devastating with the amount of people living in LA and just right on top of the fault.

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Old 10-23-2008, 08:39 PM
 
Location: Zurich, Switzerland/ Piedmont, CA
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Quote:
Originally Posted by jessemh431 View Post
Not to ruin the thread, but I think the Newport-Inglewood Fault is more dangerous.

NEWPORT-INGLEWOOD FAULT ZONE (http://www.data.scec.org/fault_index/newping.html - broken link)

According to that site, the last major quake from it was in 1933 and if it causes another quake now, it could be from 6.0-7.4. This would be devastating with the amount of people living in LA and just right on top of the fault.
Obviously the more people and homes, the greater the risk of damage. Although Munich RE, a global insurance carrier did rank SF behind Tokyo as the place for the 2nd most damage in dollar value should a huge quake occur. LA was 3rd.

Also, 1933 seems fairly recent in terms of earthquakes but we never know what's going to happen-even with all the science.
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Old 10-23-2008, 09:04 PM
 
Location: Mission Viejo, CA
2,498 posts, read 10,285,535 times
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The Los Angeles area and the Bay Area face significant damage if a major earthquake were to occur. 1st place, 2nd place, 3rd place, 4th place, etc... ALL are in danger and it isn't a good thing. I'm glad I am paying for the earthquake insurance, but you can't put a price on your life. I just hope my family and I are not in the wrong place when a big one hits [I hope everyone is not in the "wrong place"]
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Old 10-23-2008, 09:11 PM
 
Location: Zurich, Switzerland/ Piedmont, CA
32,319 posts, read 55,123,408 times
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Quote:
Originally Posted by missionhome View Post
The Los Angeles area and the Bay Area face significant damage if a major earthquake were to occur. 1st place, 2nd place, 3rd place, 4th place, etc... ALL are in danger and it isn't a good thing. I'm glad I am paying for the earthquake insurance, but you can't put a price on your life. I just hope my family and I are not in the wrong place when a big one hits [I hope everyone is not in the "wrong place"]
So true. I just reread my post. So stupid.

Anyway, we really need to prepare and I fear we're going to see a California version of the Katrina aftermath is people dont make provisions.
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Old 10-20-2011, 09:53 PM
 
Location: Zurich, Switzerland/ Piedmont, CA
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Just sayin' dear friends cause I care. After the events of this evening, We can never be too ready.

God Bless.
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Old 10-21-2011, 07:58 PM
 
Location: Carrboro and Concord, NC
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All of them are seriously dangerous.

The stuff about the Cascadia subduction zone is especially fascinating, and spooky, because quakes happen with far less frequency up there - 250-500 year intervals, but when they do they are huge - ~9.0 undersea quakes. The 1700 quake apparently sent a massive tsunami into the Oregon/Washington/British Columbia coast, and Lewis & Clark described seeing what looked like severe damage from shaking well inland up the Columbia River Gorge - lots of landlsides - decades after that quake struck. There is a similar subduction fault off the north coasts of Puerto Rico and Hispanola, which is something East Coasters should know about.

The California quakes don't hit those kinds of magnitude, and aren't underwater, but they hit a lot more people.

The quake zones east of the Rockies - so-called inter-plate quakes - like the 1811-1812 New Madrid quakes in southeast Missouri (magnitude around 8.0), the 1886 quake in Charleston SC (magnitude of 7.0+), and the quakes that struck near Quebec City/Charlevoix in the 1920s and 1940s (both between 6.0 and 7.0) are FAR more rare, but they are certainly (obviously) not unknown, and they can be just as strong. There are "midcontinental" fault systems under the St Lawrence River, the New Madrid Fault which runs from NE Arkansas to SW Indiana, faults in the Yellowstone area, one along the coast of Massachusetts, and one in coastal South Carolina, and those just are the ones we know about - they have all produced at least one 6.0+ quake at some time between the colonial era and now.

In regards to tsunamis - there have been a handful of East Coast tsunami events - the 1700s quake that struck Lisbon, Portugal produced small waves on the east coast of the US, and destructive tsunamis in the Windward Islands. Since then, early 20th century quakes in Puerto Rico (1920s) and off the coast of Newfoundland (1940s) both produced tsunamis that were mostly localized, but nonetheless destructive. The tsunami generated by the Puerto Rico quake produced one death in the Mid-Atlantic States, when someone was swept out to sea.

And in any of those eventualities, there's no way to know. It's like living with tornado risks, or hurricane risks. If you're smart and know what can be likely where you live, you prepare and inform yourself, to the best of your abilities.
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Old 10-27-2011, 07:01 PM
 
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The next big New Madrid shaker is going to be a real bummer. Imagine all the non reinforced brick buildings in Memphis and St. Louis. Even places like Chicago, Cincinnati, Louisville, Little Rock, Jackson, Columbus, Indianapolis, etc, etc may be in for a rude awakening. Look at what a mere 5.8 did on the East Coast.
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Old 10-27-2011, 07:04 PM
 
12,825 posts, read 20,126,238 times
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Quote:
Originally Posted by jessemh431 View Post
Not to ruin the thread, but I think the Newport-Inglewood Fault is more dangerous.

NEWPORT-INGLEWOOD FAULT ZONE (http://www.data.scec.org/fault_index/newping.html - broken link)

According to that site, the last major quake from it was in 1933 and if it causes another quake now, it could be from 6.0-7.4. This would be devastating with the amount of people living in LA and just right on top of the fault.
The hood would get hit the hardest in this scenario. Sad actually. They are the least likely to have done seismic strengthening.
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