

Liquefaction from the Sendai earthquake – a remarkable video - elliottcarlson
http://blogs.agu.org/landslideblog/2011/03/17/liquefaction-from-the-sendai-earthquake/

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martinkallstrom
Even more startling is the liquefaction happening in Christchurch:

<http://www.youtube.com/watch?v=2WoKu5VxKgs>

Here is an awesome video by a Christchurcher showing how the sediments pouring
up through earthquake cracks have the perfect mixture of water and soil to be
prone to liquefaction:

<http://www.youtube.com/watch?v=1KqlAMWMjOE>

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NZ_Matt
I spent a week clearing this crap out of people back yards with the student
army of volunteers. They estimate 200000 tonnes of the silt had to be cleared.

Here's an example of the silt coming out of the ground minutes after the
quake. <http://www.youtube.com/watch?v=e_twYpUJl9o>

And here's a good explanation
[http://mandenomusings.wordpress.com/2011/03/03/christchurch-...](http://mandenomusings.wordpress.com/2011/03/03/christchurch-
earthquake-liquefaction-explained/)

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wmwong
For those of us who are not familiar with the term liquefaction. In simple
terms, I think it means the soil becomes like quick sand because of the
earthquake.

<http://en.wikipedia.org/wiki/Earthquake_liquefaction>

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michaelcampbell
Exactly. Liquefaction is _not_ water coming up from the ground, although
that's a side effect of it.

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dstein
That's the most casual walk through a Japanese park during an earthquake I can
imagine.

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aaronbrethorst
That is really disturbing, and it reminds me of something I just read the
other day.

For any Seattle startup folks, just remember that all of Pioneer Square (and
then some...) is a liquefaction zone[1]. Also, don't forget that the Viaduct
is a death trap, and you really are better off never setting foot (or wheel, I
guess) on it.

[1] [http://www.thestranger.com/slog/archives/2011/03/16/more-
sea...](http://www.thestranger.com/slog/archives/2011/03/16/more-seattle-
quake-stuff)

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Anechoic
> _For any Seattle startup folks, just remember that all of Pioneer Square
> (and then some...) is a liquefaction zone_

For that matter, so is a large chunk of the Bay Area.

Whether it's earthquakes, wildfires, bizzards, tornados, hurricanes, etc there
is always gouing to be something pretty much wherever you settle.

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Florin_Andrei
> For that matter, so is a large chunk of the Bay Area.

More specific?

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bronson
Anywhere that's reclaimed infill: The Marina, most of Foster City, Treasure
Island, parts of Fremont, etc.

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nix
Large areas south of market.

liquefaction hazards for SF:
<http://gmw.consrv.ca.gov/SHMP/download/pdf/ozn_sf.pdf> other PDFs:
<http://gmw.consrv.ca.gov/SHMP/html/pdf_maps_no.html>

~~~
michaelcampbell
I found it mildly interesting how the liquifaction areas are colored in a
pleasant tone of green.

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malesniak
Quite a remarkable video... a little less so when you get to the end and he
informs you of the history of Tokyo Central Park (reclaimed land). Still...
unbelievable. Much less dramatic that the Google images of entire communities
washed from the Earth... devastating.

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kazuya
I've been in Tokyo for more than 20 years but I cannot tell which 'Central
Park' this is.

Shinjuku Central Park is a well known one and it is surrounded by skyscrapers,
but this one doesn't have them.

Any hints?

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brianbreslin
he says it is in reclaimed part of tokyo bay. so wouldn't have skyscrapers ALL
around, but should have some in a few of the shots.

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kazuya
Ah I didn't notice it as I turned audio off.

Now I managed to spot it. The park is actually Makuhari Kaihin Park (幕張海浜公園)
in Chiba, not in Tokyo (that's why I was not aware of it).

And yes it is on reclaimed land, the homepage of the park in fact mentions
liquefaction.

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delinka
I've never experienced an earthquake. As such, the cracks and drifting earth
make me doubt the reality of such a video. Does this drifting actually occur
at the surface like that? Edit: speeling ;-)

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michaelcampbell
I've been in 2 about 20 years ago; both ~5.1. If memory serves there were 2
distict types of shaking. The first was a fairly high frequency vibration that
shook the walls and mimic what you see in movies; $#@! flying off shelves,
etc.

The second came a few seconds later, and was a slow back and forth horizontal
movement of the ground. I remember it being a bit faster frequency than that
video shows, maybe about 1Hz, but it seemed like the ground was just moving
fairly slowly back and forth a few inches.

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delinka
I've heard many accounts of these phenomena from others. What I'm having
difficulty with is the relative motion of the different pieces of earth. I
live on pretty solid ground away from active fault lines. If one of our minor
fault lines ever acted up, I could certainly imagine the kind of motion you
mention. But if my property "cracked," I'd expect to _feel_ the swaying motion
and that each piece of my yard would move in the same direction preventing me
_seeing_ the motion. On further consideration that the park in the video is
built on a former bay, I supposed the quake could be making the dirt float
around on the mushy underside.

The first thing I noticed was an oddness about the crack in the sidewalk. It
seems to have cracked perfectly along some crack line that's outside of the
sidewalk (not likely - just because dirt cracks underneath doesn't mean the
concrete will crack exactly where the dirt does) and there seems to be some
rubbery surface where the crack ends in the sidewalk (it stretches as the
parts of earth move in different directions.) Not like the pure concrete
sidewalks I'm accustomed to, but Tokyo is worlds away and maybe it's not just
concrete.

P.S. Why the downvoting on my original post? Is it not a valid question?

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chronomex
That pavement is most likely asphaltic concrete (commonly, though incorrectly,
known as "asphalt"), which is a mixture of asphalt and sand/gravel aggregate.
It's fairly flexible, at least compared to Portland cement concrete.

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BasDirks
"a sombrero, and a huge clock"

Is this Chuck Norris wielding the camera?

