
In San Francisco, a Sinking Skyscraper and a Deepening Dispute - BinaryIdiot
http://www.nytimes.com/2016/09/23/us/san-francisco-millennium-tower-dispute.html
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BinaryIdiot
It's leaning 6 inches so I'm assuming it's going to continue to lean further
and further each year unless they make modifications to the building (so
lopping off the top 20 floors or whatever else that could fix or mitigate it).
At which point does it lean far enough that they have to demolish the
building? At which point does the entire building become a safety issue should
an earthquake (or even "the big one") ever hit?

Working in the city these tall buildings going up kinda worry me with the area
being prone to earthquakes. I'm not a structural engineer so maybe my worries
are misguided but they're there.

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idlewords
Tall buildings built to seismic code are some of the safest structures to be
in in an earthquake. Though you'll probably need a change of underwear
afterwards:
[https://www.youtube.com/watch?v=NisWbAXfyWI](https://www.youtube.com/watch?v=NisWbAXfyWI)

~~~
ScottBurson
I was asleep on about the 20th floor of a hotel in LA in 1992 when the 7.3
Landers and 6.5 Big Bear earthquakes hit [0]. The building (which I believe
was on rollers) was rocking quite noticeably.

I wasn't afraid for myself, though by the large, low-frequency motion I could
tell it was a very large earthquake whose epicenter was a good distance away.
I hoped it hadn't just taken out San Diego.

Though I'll admit, to go back to sleep and then be wakened by a _second_ large
quake (Big Bear hit about 3 hours later; it is considered a separate quake
rather than an aftershock) was starting to get a bit freaky.

[0]
[https://en.wikipedia.org/wiki/1992_Landers_earthquake](https://en.wikipedia.org/wiki/1992_Landers_earthquake)

[1]
[https://en.wikipedia.org/wiki/1992_Big_Bear_earthquake](https://en.wikipedia.org/wiki/1992_Big_Bear_earthquake)

~~~
cgriswald
I can't even imagine.

My daughter was born the day a 4.0 quake hit Piedmont, CA. I was in the fourth
floor of a hospital in SF. The hospital beds were rolling around and I could
feel the building moving. Very humbling for a guy from Minnesota who had only
experienced minor quakes that didn't do much more than make it feel like a
semi-truck was passing by outside. I don't know how I looked, but the mother
of my child looked over at me and was like, "that was nothing."

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jzl
A lot more details in this new article:

[http://www.sfchronicle.com/bayarea/article/Sinking-
Millenniu...](http://www.sfchronicle.com/bayarea/article/Sinking-Millennium-
Tower-s-developer-built-9278364.php?t=699cf311b0)

Including comparisons to neighboring buildings with a very well done chart.
And this frightening statistic:

 _On Friday the transbay authority released a report by the engineering firm
ARUP, showing that the Millennium Tower is four to five times heavier than any
other building in the area with a similar foundation, including 100 First St.,
199 Fremont St. and 555 Mission St. Building weights are measured in kips —
1,000 pounds — per square inch of pressure on the soil below. The tower at 555
Mission, for example, is 487 feet tall compared with 645 for the Millennium,
but it exerts 2.4 kips per square inch while the Millennium exerts 11.4 kips._

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trhway
25 years ago working summer construction projects doing foundations in Siberia
we were explained what depth to reach and why (permafrost etc.), and in
particular we were taken on a short sightseeing tour of couple of buildings
for which it wasn't done properly - the screwed geometry of those buildings
one could see with naked eye from distance. I guess that tower in SF will be
serving similar educational purpose for decades to come :)

~~~
tinco
In my hometown there is a building that was built in 1529 and leans more than
the tower of pisa. It was intended to be taller than our rival cities tower,
but it already started sagging during construction. To counteract the sagging
the builders actually made kinks in the construction so next layers would be
level again, but obviously this didn't help. They never got further than the
base of the tower, which still stands and is a fun place to visit.

[https://en.wikipedia.org/wiki/Oldehove_(tower)](https://en.wikipedia.org/wiki/Oldehove_\(tower\))

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supahfly_remix
Because the building sank 8 inches, did the builder subsequently need to fix
they entrance to the building? Does one step down into it from street level?

~~~
helper
No. Besides some cracks in the sidewalk you can't tell that it has sunk. (I
work across the street from the Millennium Tower).

~~~
supahfly_remix
Thanks. It must have pulled down the adjacent sidewalk with it, creating a
more gradual slope then.

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kalleboo
That was the conclusion the last time this story came up a month or so ago.
They've also been continually re-pouring the sidewalk concrete so you can't
see the cracks.

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newman314
How does this not snap the pipes going in and out of the building?

~~~
jzl
The city has stated that water and sewage connections to the building might
soon fail depending on how much more sinking there is.

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pstuart
It's kind of mind blowing that a building of this magnitude would go in a
location that is bay fill in a region renowned for earthquakes, yet not have
pilings going down to bedrock.

The real aftershocks are going to be the lawsuits over this.

~~~
nashashmi
Unless I am losing my memory, I remember learning in geology class that
seismic waves travel the least in clay and most in rock.

~~~
knorby
Soil liquefaction is the real risk during earthquakes. Clay absorbs the energy
and shakes a great deal more, and the soil can potentially destabilize further
and allow structures to sink in.

~~~
wlesieutre
For anyone not familiar, this is an effect where if you load wet soil just
right it will break the structure of the soil grains and turn into a fluid.
Demo here, you can skip the first minute if you're short on time:
[https://www.youtube.com/watch?v=-X9-4tWpMCo](https://www.youtube.com/watch?v=-X9-4tWpMCo)

Wikipedia has more information and some good photos:
[https://en.wikipedia.org/wiki/Soil_liquefaction](https://en.wikipedia.org/wiki/Soil_liquefaction)

It's a really cool and equally terrifying phenomenon if you're used to
thinking of the ground as a solid object. Plenty of videos on YouTube as well.

EDIT- Here's a car that sunk into the ground, which then resolidified around
it: [https://youtu.be/2WoKu5VxKgs?t=50](https://youtu.be/2WoKu5VxKgs?t=50)

[http://izismile.com/2012/08/31/christchurch_liquefaction_26_...](http://izismile.com/2012/08/31/christchurch_liquefaction_26_pics.html)

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partycoder
Many San Francisco buildings are placed in a zone called the liquefaction
zone. There are maps that show which areas will suffer liquefaction in the
event of an earthquake.

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Zhenya
Map for reference:
[https://www.google.com/maps/d/u/0/viewer?mid=19TDkFjIeO9wD5s...](https://www.google.com/maps/d/u/0/viewer?mid=19TDkFjIeO9wD5snoxkbMQBjsjUg&hl=en)

~~~
crazy2be
For those curious, this is a (crappier) map of the whole bay:
[https://commons.wikimedia.org/wiki/File:SFBALiqufactionMap.j...](https://commons.wikimedia.org/wiki/File:SFBALiqufactionMap.jpg)

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aristus
Hi-res PDF of that bay map:
[http://pubs.usgs.gov/of/2000/of00-444/of00-444_8b.pdf](http://pubs.usgs.gov/of/2000/of00-444/of00-444_8b.pdf)

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rando444
This exact same thing is happening in Oslo.

All of the new skyscrapers downtown around the opera house are sinking into
the ground, and new construction is making the situation worse.

Curiously I can't find any articles about this in English, but here is one in
Norwegian.

[http://www.tu.no/artikler/bjorvika-
synker/231007](http://www.tu.no/artikler/bjorvika-synker/231007)

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VonGuard
Last time this was mentioned on HN, someone asked me to go take pictures of
the building. I did:

[https://www.flickr.com/photos/vonguard/albums/72157672701771...](https://www.flickr.com/photos/vonguard/albums/72157672701771432)

You can see the bowing of rht sidewalk outside, and where the foundation is
breaking away from the ground.

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coldcode
I find it amazing that an earthquake prone city had no requirements for
building a skyscraper in a reclaimed soil area needing outside verification of
the engineering plan.

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rwmj
Anyone wish to comment on whether "lopping off the top 20 floors" is an even
remotely plausible plan? It sounds completely implausible to me, but then I'm
not a civil engineer.

~~~
blaze33
Sounds indeed implausible but it has been done before:
[https://youtu.be/8_4G_8gEjng](https://youtu.be/8_4G_8gEjng)

~~~
BinaryIdiot
Okay that is the coolest thing I've seen in a while. I never really thought
about how you'd dismantle a building without a single demolition event. I
wonder how practical / cost effectice this is in comparison.

