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Old 03-13-2011, 09:00 PM
 
Location: state of enlightenment
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In the last 6 years: Indonesia, Haiti, China, Chile, New Zealand, Japan. Now a volcano has gone off in Japan. No doubt the eggheads with spreadsheets will say there's nothing unusual about the recent earthquakes but it sure seems unusual in number and intensity and heading toward a climax in ... 2012?. Of course there's no way to know when and where the next big one will strike but there are some obvious candidates that are overdue. Turkey has a very active fault. It's been over 10 years since the last big one. Same for Greece. US west coast - the last big one was 89 in SF. Seems like the next big one for LA has been predicted forever. If it happens soon it would be pretty hard to argue there's no trend. I hope not but I ain't goin to LA anytime soon.
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Old 03-13-2011, 09:36 PM
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Location: Ohio
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Don't forget the New Zealand earthquake, about 2 weeks ago. It did billions of dollars worth of damage.
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Old 03-13-2011, 10:50 PM
 
Location: 3rd rock from the sun
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Quote:
Originally Posted by geos View Post
No doubt the eggheads with spreadsheets will say there's nothing unusual about the recent earthquakes but it sure seems unusual in number and intensity and heading toward a climax in ... 2012?
Egghead here.


http://en.wikipedia.org/wiki/List_of...ry_earthquakes
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Old 03-14-2011, 12:32 AM
 
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Originally Posted by geos View Post
No doubt the eggheads with spreadsheets will say there's nothing unusual about the recent earthquakes but it sure seems unusual in number and intensity and heading toward a climax in ... 2012?.
Information overload often sensationalized by the media that produces the perception of events that are "unusual in number and intensity".
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Old 03-14-2011, 09:07 AM
 
Location: state of enlightenment
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Don't confuse me with graphs!
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Old 03-14-2011, 11:10 AM
 
Location: Londonderry, NH
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The earthquake frequency seems to be fairly even over the years. Looks like the NBO in about three years or so.
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Old 03-14-2011, 11:14 AM
 
Location: Victoria TX
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You are defining "Big One" in terms of the number of human beings who happen to be in the way, which has nothing to do with seismic science.

"The Universe has its own laws, all of them indifferent to the contradictory dreams and desires of humans." ---Jose Saramago

The credentialing of the current quake in Japan as a "Big One" is inflated mainly by the number of people nearby, the proportion of those who own videocams, and the market value of their homes and possessions.
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Old 03-14-2011, 11:21 AM
 
Location: Londonderry, NH
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I was using seismic energy release to describe "Big One". Say Rhicter Scale 9.0 ot thereabouts.
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Old 03-14-2011, 08:53 PM
 
Location: Carrboro and Concord, NC
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Originally Posted by GregW View Post
I was using seismic energy release to describe "Big One". Say Rhicter Scale 9.0 ot thereabouts.
Quakes of that magnitude - say 8.5+ are only generated by a specific type of fault: subduction faults, when an oceanic plate is subducted (overriden) by the movement of a continental plate. Of the large quakes over the last decade - this most recent quake, the Chilean quake a year ago, and the series of quakes in Indonesia that began in 2004 were all of that specific type. By definition, these quakes and faults are under water, and due to the energy release, they displace massive quantities of water.

Most subduction zones are in the Pacific Basin:

  • Off the NE coast of Japan
  • Off the E coast of the Philippine archipelago
  • Off the Pacific coast of the Kamchatka Peninsula of Siberia (location of multiple 8.5+ quakes during the 20th century)
  • Along the southern coast of the Aleutian Islands and S central Alaska (location of the 1964 Good Friday quake, and a large [8.5+] quake in the Aleutians 9 years earlier)
  • Off the SW coast of British Columbia and the W coast of Washington and Oregon (location of a January, 1700 quake that sent large tsunamis into what is now the Pacific Northwest, and sent a smaller tsunami to Japan, which was detailed in Japanese literature of the time, which pinpointed the precise date)
  • Along the Pacific Coast of El Salvador and Costa Rica
  • Along the W coast of South America from Ecuador south (location of the many 8.5+ Chilean quakes)

In the Atlantic:
  • Off the N coast of Puerto Rico (a quake in 1919 sent a large, localized tsunami into the NW coast of Puerto Rico)
  • W of the entrance to the Mediterranean Sea (a quake in the 1700s nearly destroyed Lisbon, and sent large tsunamis into the Caribbean, and up the SW coast of Europe)

In the Indian Ocean:
  • From the Andaman & Nicobar Islands along the S coast of the Indonesian archipelago (location of all of the large Indonesian quakes)

In the Mediterranean:
  • Along the S coast of Crete (a quake in the 4th century and another in the 12th generated very large tsunamis in the eastern Mediterranean basin)

All of these areas are capable of generating 9.0 quakes, though not all have been (yet) documented as doing so. The frequency of great quakes along them is a consequence of the speed of plate movement, and in some areas that movement is a lot faster than in others: quakes of this magnitude strike Indonesia, Kamchatka and Chile more than once a century. By contrast, the last quake of this size in the Cascadia subduction zone (off the coast of OR, WA and BC) was in January 1700 - that quake did generate very large tsunamis.

Obviously faults on land don't produce tsunamis. Slip faults (like the San Andreas), whether on land or under water, are more frequently active, which dissipates some of their energy, thus quakes over about 8.5 have - thus far at least - never been seen on them. Spreading faults (like seafloor ridges or the Rift Valley in E Africa) likewise don't generate quakes of this magnitude. With either, large quakes can still be unbelievably destructive - as in Haiti - due to landslides, local building standards and other local factors.

Some mid-continental faults - which are a bit more mysterious as they are found in the centers of tectonic plates - do occasionally produce quakes of around 8 or 8.5: the quakes in western China, the Gujarat quake in India (1990s), the New Madrid quakes in Missouri (1811-1812), the Charleston SC quake (1886), and the Boston quakes (1740s), were all examples of mid-continental quakes.
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Old 03-15-2011, 08:01 AM
 
28,736 posts, read 43,817,990 times
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Quote:
Originally Posted by jtur88 View Post
You are defining "Big One" in terms of the number of human beings who happen to be in the way, which has nothing to do with seismic science.

"The Universe has its own laws, all of them indifferent to the contradictory dreams and desires of humans." ---Jose Saramago

The credentialing of the current quake in Japan as a "Big One" is inflated mainly by the number of people nearby, the proportion of those who own videocams, and the market value of their homes and possessions.
You forgot to include the amount of money the media thinks they can make off the disaster.

Anybody seen Kadafi Duck lately?
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