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Author Topic: How big were the lastest few quakes in china which have caused such devastation?  (Read 15869 times)

Offline Karen W.

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So many people dead and so many still buried and sufferring...where are they on a fault line......are or are they?
My heart goes out to all of them...  The outcome is so poor right now, even with lots of man power.AS i understand it the weather is not helping at this point....
does any one have any details about the quakes etc ???


 

Offline Bass

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According to latest from USGS, 7.9.

Occurred in an area of high seismicity along a reverse fault that marks the boundary between Eurasia and SE Asia.  This is a convergence zone, with one block moving above another.
http://earthquake.usgs.gov/eqcenter/recenteqsww/Quakes/us2008ryan.php#details
 

Offline Karen W.

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WOW 7.9.. and I thought 7.2 was bad! Hey bass.. could a 7.2 here be different in its effect in a different area.. you know what I mean..? Can the geographic position of where the quake hits make a 7.2 more strong then it might be in a different place, given what the ground make up might be in that particular region..??? Is there a difference in its effects or movement?

Thanks Bass
« Last Edit: 14/05/2008 16:00:36 by Karen W. »
 

Offline Bass

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Earthquakes can have different effects depending on lots of things.  Depth of earthquake makes a difference, type of fault and fault movement, rock type, surface geology (this can make a huge difference), etc.
Areas with sediment fill (mud, sand, gravel) tend to amplify surface seismic waves, while areas of bedrock tend to diminish those same waves.
So a 7.2, depending on location, depth, surface rocks, population and infrastructure, could cause more damage than a stronger earthquake.
 

Offline Karen W.

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I was thinking that it might.. That is interesting isn't it? I really don't know much about my own geography here but from digging for wells I have seen that where I am we have rocks and a lot of clay in our ground areas here as well as a nice thick layer many feet down of something very black as I recall.. but I can't remember what the man called it... we have this surface layer of grass,dirt, and rocks, but then we get to this kind of yellow dirt and gray looking clay then that goes down for a long time then they hit this sloppy yellowish orange layer then this black looking stuff I could have sworn as a kid that it looked like charcoal under there by the damp layers...and usually more clay and water.. Its been years though!
 

Offline Bass

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Here's another link with a map and short narrative about the China earthquakes:
http://earthobservatory.nasa.gov/NaturalHazards/shownh.php3?img_id=14833
 

Offline Karen W.

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Offline Karen W.

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Here's another link with a map and short narrative about the China earthquakes:
http://earthobservatory.nasa.gov/NaturalHazards/shownh.php3?img_id=14833

OH MY GOSH! so many people dead.. and the count is still rising... Oh my Gosh... I don't usually watch the news but caught a tiny snippet this morning.. oh my This is horrible and hundreds of thousands of people...

oh.... my.. thats horrible... It was felt from great distances! damage all over the place....
 

Offline JimBob

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As long as there are active faults there will be earthquakes. The latest one in Sichuan was on hard rocks - they transmit the shaking much more efficiently than the softer sedimentary rocks or softer metasedimetary rocks (Franciscan Formation)in California.
 

Offline Bass

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Karen might find this particularly interesting (since she lives in California)

USGS releases possible earthquake scenario for major shake in southern California

http://www.usgs.gov/newsroom/article.asp?ID=1947&from=rss_home
 

Offline turnipsock

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http://tsunami.geo.ed.ac.uk/local-bin/quakes/mapscript/demo_run.pl#

This is the page I use to follow eathquakes. It gets updated quite regularly. There are some good sub pages for each quake.

One of the aftershocks hit 5.9 a few days ago, but there seems to be about three a day in that area.
 

blakestyger

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This is massive - especially when you consider that the Richter is a log scale.
 

Offline rosalind dna

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I thought that the biggest on the Richter Scale of the Earthquakes
are 0.10+ ??
 

Offline JimBob

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The largest is usually considered a 10, which would shale the earth on it's axis. Never had anything such as that except for some massive meteorite impacts.
 

Offline rosalind dna

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The latest big earthquake was earlier tonight and in the Colombian capital, Bogota. We will have to see what kind of overseas aid they get and how fast if it's needed.
http://earthquake.usgs.gov/eqcenter/recenteqsww/Quakes/us2008skbn.php

http://news.bbc.co.uk/1/hi/world/americas/7418876.stm

 

Offline JimBob

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There is a huge difference in scale and magnitude of the two earthquakes.

The Chinese earthquake is considered to be almost a great earthquake - less than 10 of these happen a year and one just a notch up on the logarithmic scale of earthquake measurement would have made it a "great" quake. This Chinese quake is probably in the one of these a year catigory - 80,000 people dead is the latest number I have heard or read.

The Bolivian quake is just a "moderate" earthquake. Only 6 - 10 people died and "At least 15 houses and a church were reported to have been damaged, says the Efe news agency." (Second link above)

Compare that to China - 80,00 dead, nearly 500,000 rather severely hurt and you can see that the human toll is so much larger in China than in Bollivia. This, as well as whole cities destroyed  as compared to a few buildings in South America show how much more powerful the Cinese quake was.
 
For a complete discussion of the Richter Scale and earthquake magnitude see: http://en.wikipedia.org/wiki/Richter_magnitude_scale
 

Offline rosalind dna

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The latest quake was on 29th May in Iceland and it was a strong one
on the Richter Scale 6.5 which is a strange that so many have happened this May.

The Sichuan quake in China are still getting after-shocks over 3 weeks since the quake happened.

http://news.bbc.co.uk/1/hi/world/europe/7426369.stm
http://tsunami.geo.ed.ac.uk/local-bin/quakes/mapscript/show_map.pl?lon=-20.9161&lat=64.0190&magn=6.2&mode=each_quake&layer=background&layer=plate
 

Offline Kenwood04

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I think it depends to some extent, how the countries infrascuture is, as to what damage is done by an earthquake?  If you build crappy leantos as "habitable " buildings they will be the first to come down.  And in China that is the one of the "bug bears", if the buildings had been built properly, they might hav survived and the children in them.
 

Offline rosalind dna

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I think it depends to some extent, how the countries infrascuture is, as to what damage is done by an earthquake?  If you build crappy leantos as "habitable " buildings they will be the first to come down.  And in China that is the one of the "bug bears", if the buildings had been built properly, they might hav survived and the children in them.

What about the biggest Quake so far this year in Iceland that's a developed country. That suffered too. Where wouldn't when a quake, cyclone happens??

No where
 

Offline Kenwood04

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not sure if the one in Iceland was bigger than the one in China?  Certainly the damage to buildings was slight and there were no deaths.
 

Offline rosalind dna

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But I meant as the Icelandic Quake was shown up on the Richter Scale as 6.5. to have been the biggest one so far in 2008.
 

Offline JimBob

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rosalind,

the largest quake this year was the 7.9 quake in China. see the USGS list at:

http://earthquake.usgs.gov/eqcenter/recenteqsww/

the iceland quake is listed as 6.3 on the richter scale. that means the chinese quake was a minimum of 900 times more powerful than the one in iceland. stated another way - if the iceland quake was equivilent to 100 sticks of dynamite, the chinese quake would have been at least 9000 sticks of dynamite.

For more info on the richter scale see: http://en.wikipedia.org/wiki/Richter_scale

pardon the lack of caps - typing with one arm for a while.
 

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