Japan is a highly volitile region, tectonically speaking, yet they've managed to build lots of tall buildings safely. How? By having some of the strictest building codes in the world, yet allowing development within those rules.
Meanwhile, outside of SF itself, the Bay area refuses to build any real density that's desperately needed, using earthquakes as (one of many) excuses for NIMBYism and entrenched interests of landlords.
The leaning building across from my office, for example, has nothing to do with seismic issues but basic design/engineering/construction flaws in not extending the pile footings deep enough to solid ground as others in the area have such as the new Salesforce tower.
Ron Klemencic, the chief executive of Magnusson Klemencic Associates, the company that did the structural engineering for Salesforce Tower, says he agrees that water and sewage systems need higher strength requirements, but not high rises. “Buildings falling on top of other buildings — that’s not going to happen,” Mr. Klemencic said.
They never explained why Klemencic's reasoning. Care to explain why "buildings falling on top of other buildings — that’s not going to happen"?
1: https://youtu.be/r0tgEYiTNd4 (0:35 and 0:45)
I am very skeptical of anybody, no matter how experienced, that gets on the news and says "that'll never happen," regardless of what the "that" is.
Has he considered a skilled terrorist cell lacing only the east side of Salesforce Tower with explosives?
Either way there's probably a bigger pile on the east side, but it's not like the top floor of a 1000' building will land 1000' laterally from the base. 100' would be a long way (tho there's be lots of flying debris for a good distance).
As soon as you might start to turn the building onto its side it falls apart like a sand castle. Were this not to happen the building would have to be engineered such that it could withstand being turned on its side like that without collapsing. But they don't design them as such.
It'd be like constantly worrying about protecting yourself from lightning.
A lightning rod (US, AUS) or lightning conductor (UK) is a metal rod mounted on a structure and intended to protect the structure from a lightning strike. If lightning hits the structure, it will preferentially strike the rod and be conducted to ground through a wire, instead of passing through the structure, where it could start a fire or cause electrocution. Lightning rods are also called finials, air terminals or strike termination devices.
In a lightning protection system, a lightning rod is a single component of the system. The lightning rod requires a connection to earth to perform its protective function. Lightning rods come in many different forms, including hollow, solid, pointed, rounded, flat strips or even bristle brush-like. The main attribute common to all lightning rods is that they are all made of conductive materials, such as copper and aluminum. Copper and its alloys are the most common materials used in lightning protection.
Anyway, this is why we have a lot of earthquake preparedness, though the chance is 5% in the next 30 years.
It's not a "constant worry," so much as a plan. There's non-negligible chance of terrorist attack, so they architect in such a way to prevent it being catastrophic. There's a non-negligible chance of your office catching fire, so they put green exit signs at the door. That sort of thing.
Not even close. USGS estimates over the next 30 years are:
72% probability of a M6.7 or higher
51% probability of a M7.0 or higher
20% probability of a M7.5 or higher
All in all not since 1933 has CA lost more than 100 lives in an earthquake:
That tells me our building codes are pretty damn good.
I work at ucsb and the catilina islands recently had a 5.2 about 2 weeks ago and the building shook abit. But all in all unless we suffer an 8.0+ I'm not terribly worried (knock on wood). To put that another way, realistically for any moderate sized earthquake CA is generally well prepared in terms of architecture, unless the big one hits ... In which case just kiss your butt goodbye.
I do wish, even for the big one, that CA invested in an early warning system like Japan has ... Imagine a 5-50 seconds warning of an earthquake, that would save lives, not stricter building codes:
Here is a better, live example of the early warning:
It's also worth pointing out that there has arguably not been a large quake close to a major city center in California since 1906 (for some values of "large" and "close"). The 1994 Northridge quake, which did some $15B in damage, was probably the best recent preview we have. Loma Prieta certainly did serious damage, despite being (as I recall) some 75 miles from San Francisco.
The real test is when the Calaveras Fault that runs up the east side of the SF Bay breaks. The last time was 1868, when there wasn't much there; estimated magnitude was 6.3 to 6.7. A quake of that size on that fault now — and it's getting to be likely, in the next two or three decades — is going to make a hell of a mess. We'll find out then how well a lot of things hold up.
I don't think it would cumulatively add up to much, but would love to see the math.
Once the building's supports fail, it drops rather than topples.
I have friends who unfortunately got to witness what happens when plate glass comes down. They can barely talk about it. It also means that the injured and trapped folks in the high rises are going to be without aid in buildings with dead mechanicals for awhile.
A lot of people think running into the street is what you wanna do. It is, in like, Mountain View maybe. Realistically you want to just jump under the nearest thing you can and hope for the best. If you're in the Financial District in the middle of the street... well your friends apparently have seen what that'll look like.
"35 deaths and many injuries from falling masonry during the 2011 Christchurch earthquake. Buildings with dangerous parapets, facades and verandahs" . That was 20% of total deaths.
Certainly near a skyscraper, you want to go inside, since if it pancakes, being outside won't help anyway - debris will hurtle horizontally.
During the Loma Prieta Earthquake a bunch of my coworkers fled the building and took shelter in the parking lot under the power lines.
Nowhere in the article did anybody make such a claim. It was to illustrate the general problems of building in that area even without an earth quake, which leads me to the other point, what IMO is the main issue, and I think is pretty independent of how much effort is spent on any one building: The potential for soil liquefaction. They included several maps showing that many of the tallest buildings are built pretty much exactly over ground that might suffer that fate in a big earth quake. How would any individual design help? Compared to the alternative of not building the tallest structures right over those spots. The maps also showed plenty of more solid ground, but that is where there are mostly lower buildings.
I would like to hear your opinion on that issue.
As for your doubts on the entire article, it seems to me they asked quite a few specialists? Are they all mistaken?
Well, I certainly would like you to be right, I used to live in SF and I still love the entire greater Bay Area.
I share the GP's doubts on the article. The practicing specialists they talked to certainly don't think there's a gamble: they actively pursue and design sky scrapers in the City. I think their words are being misused in a way that makes them seem like they agree with the article's premise.
Which, for those of us who are not structural engineers and cannot review the work to see that it is indeed well done...
As a structural engineer on the west coast, I can say that neither of these are standard. Tuned mass dampers (TMDs) are commonly used for reducing wind-induced vibration, but not for seismic applications. Nor have I ever designed, seen, or heard of 'dynamic elements in the foundation'
The reason you can't rely on TMDs is because they are tuned to a structure's elastic period of vibration. That is to say, the materials are still in their elastic range. When a ductile structure is subjected to a sufficiently large earthquake, elements of the seismic force resisting system (SFRS) will yield. Hence the period will elongate. Hence the damper will be detuned and may not provide any benefit at all.
2) From what I understand, China has a completely different design philosophy. They design structures to remain elastic, under certain earthquakes, which would then allow for TMDs.
It's likely because you're implying "dynamic" is a "buzzword" in a discussion about structural engineering and seismic movements (which is, by definition, a dynamic system).
Also I don't really think there's a background you can have where you don't understand, or cannot lookup, the difference between dynamic and static if you really cared to understand. Seems more like self-important rhetoric than anything.
For me, the question is not about whether high quality projects are going to be okay. The question is: on what basis do I believe there has been sufficient oversight to guarantee the soundness of new construction?
I can remember talking to SPUR members in 2001 about how problematic it was to extend downtown development into SOMA, etc, due to liquefaction and uncertainty. When the building craze hit, it felt like it brushed these concerns aside, rather than answer them. Now we have leaning buildings that don’t meet basic construction requirements. It doesn’t inspire a lot of faith.
You say that, and then you claim that seismic engineering is free from such flaws? That seems a bit like hubris.
That’s how it was explained in a documentary about mission bay (south of AT&T).
edit: For those interested, this documentary explains the approach https://www.youtube.com/watch?v=SyjijQS2dAk&t=1219s
The 60-story Millennium Tower is made of concrete rather than steel, resulting in a very heavy
building. This heavy structure rests on layers of soft, compressible soil. The foundation of the
Tower, however, consists only of a concrete slab supported by short piles that fail to reach the
bedrock below. That foundation is inadequate to prevent settlement of a building with the weight
of the Tower. In contrast, the Salesforce Tower and 181 Fremont Tower, also adjacent to the
Transit Center, are supported on piles drilled down to bedrock. Millennium Partners’ poor design
decision is the cause of the tilt and excessive vertical settlement of the Millennium Tower.
> The 2011 Great East Japan Earthquake caused the severe liquefaction of reclaimed lands in the Tokyo Bay area, from Shinkiba in Tokyo through Urayasu, Ichikawa and Narashino Cities to Chiba City.
Most of Tokyo comprises low-rise (1-10 story) buildings.
Second, is there anything that can be done such that the soil won't suffer from liquifaction or will to a lesser degree? Probably expensive to do, yes, but surely there are means.
And there's probably a million other ideas that might work that I don't even know of. It's silicon valley, that's where ideas come from, right? "Impossible" usual gets San Francisco types all excited.
There's a downvoted reply to my original comment saying that I haven't actually tried to build these- and they are correct. I'm not a civil engineer. But I am a firm believer that if you make strong regulations and enforce them, clever engineers always find a way, at a cost. But the hard part of that isn't the engineering, it's having the political willpower to enforce strong rules.
What caused the most damages was the fires after the earthquake.
Hopefully SF has a better fire department now than in 1906.
As a result, SF now has a backup hydrant system! Those big fat multi-colored hydrants are all connected to a fire-only water system that's gravity-fed from cisterns all over the city. The colors of the hydrants encode information about which cistern the water comes from, IIRC. And whenever you see a random arc of a circle made of brick inlaid in the road, that's outlining the location of a cistern.
Neighborhoods will definitely burn but containment will be more of a factor of how windy it is and how easy it is to get to water.
Wish your comment was higher up.
If you're in the Bay Area: sign up for a NERT/CERT class, buy an ABC fire extinguisher, and know where and how to shut off your gas line. Assume the fire department will not get to you.
SF NERT: http://sf-fire.org/neighborhood-emergency-response-team-nert
In such event, I would do only one thing: run.
I'm not advocating for anyone to run around playing fire fighter.
It's not clear how much of the fire damage was due to intentionally set fires; there were also a significant number of fires started unintentionally when the fire department dynamited various buildings in failed attempts to establish fire breaks. (And, hey, you were still covered if your building was dynamited!) So, lets hope the SFFD is better in this regard than in 1906 as well.
The insurance industry claims that only 2% of the destruction was directly due to the earthquake; 98% was from the fires. https://www.iii.org/article/san-francisco-earthquake-1906-in...
Nowadays everyone has their hot water heater and oven bolted or strapped to the wall. I'm sure there are other useful fire codes California has adopted since then but this one rule will probably prevent more fires in the next big quake than any other.
Side note from a New Yorker, it always shocks me how careful San Francisco pretends to be with building codes and environmental and safety reviews and this and that, only to go on and systematically approve a series of terrible structures. (Not before showering them with ecological awards, of course .)
The Millennium Tower was not flawed. It just unfortunately bumped into the law of large numbers. Even if all future towers in SF rest on bedrock, that still wouldn't reflect poorly the judgment of the Millennium Tower architects.
Frankly, New Yorkers should be more concerned about the seismic safety of New York buildings. In terms of seismic risk vs seismic structural resilience, New York may be facing a great chance of catastrophe than San Francisco.
While this tends to be true for large, commercial architectural projects, it’s not true for residences. A big reason why almost no one buys used homes in Japan(and if they do, they tear them down and build new) is that building codes are very loosely enforced in this domain. If I remember correctly, structural calculations to resist earthquakes aren’t even required for buildings under 2.5 stories (i.e. just about all private residences).
It’s a commonly-cited misconception that zoning is what makes housing so cheap in Japan. Zoning is a factor, but in reality it’s because housing is built pretty fast and loose as a disposable commodity.
The obvious counterproof to your argument is Millennium Tower, a 60-story skyscraper, which has sank at least 16 inches so far. Most of those one 1 side, so the building now tilts at least 15 inches at the top:
They are still trying to figure out how to fix it. Doing so could cost well more than it took to built it in the first place. One proposed plan is to anchor it to bedrock on the low side, then let the tower sink further until it's about even before anchoring the other side: https://sf.curbed.com/2018/4/16/17242450/millennium-tower-si...
I honestly think it's reasonable that the building code gives skyscrapers a lot of leeway. Traditional building codes are very prescriptive, and that works better with (common and similar) houses than (rare and varied) skyscrapers. But the ongoing clusterfuck that is Millennium Tower makes it clear we can't just trust developers to get it right. As mabbo says, they have a strong financial incentive to cut corners.
The Millennium Tower is not a "counter proof" to my argument, although it has become a bellwether for exactly the kind of posters I call out in my original post. My argument is that people on here who do armchair structural engineer and make comments like "the building code is too lax" are ignorant and full of shit. All the Millenium Tower proves is that, even with a building code, it is still possible to get unintended consequences. To the rest of your post about skyscrapers getting a lot of leeway - they don't get any more leeway than any other structure, they just have the money it takes to invoke portions of the code that allow alternative analysis methods. It just doesn't make sense financially to do some of the complex modeling for a 3 story building to shave 5% of material costs.
If anything, the building code is more stringent on skyscrapers because it does require more advanced analysis. This analysis is NOT precluded for smaller buildings, it is just not worth the money.
Because if it falls over it won't just kill 5 stories worth of people, but 50 stories plus an unknown number of people in the building it falls on, as well as creating a giant civic problem?
> ignorant and full of shit
Oooohkay, buddy. At best you are playing semantic games here. If your theory is that the building code is just fine when things like the Millennium Tower can happen, then we disagree on what "fine" means.
What portion of the building code do you think needs to be updated in response to the Millennium situation? In reality, the building code achieves a success rate far in excess of what engineers deem acceptable. It is unfortunate that the Millennium is a big glaring exception, but the fact remains.
Geotechnical engineering (the cause of the Millennium lean) remains a highly empirical field of engineering with uncertainties that dwarf structural ones. Hence there is a lot of built-in conservatism in design parameters like bearing pressures. But there are limits to the amount of information you can ascertain of what's below you that you cannot see. Looking back in retrospect and saying "well obviously they should have had longer piles" like many people have on the various threads about the tower is a pretty ignorant thing to say, and it shows that they do not have an appreciation of the engineering behind the decision. There a tens of thousands of examples of friction piles that have worked flawlessly. The engineering evidence appears to have supported the decision, but the in-situ soil conditions varied from their design model. This, in my opinion, is not a failure of codes, but an unfortunate, statistically rare outcome.
I understand that the people who built it believed that they were doing just fine. But I also understand that there are enormous pressures to keep costs low on a project like this. The notion that for this building those enormous pressures had exactly zero contribution to this outcome is a claim I certainly wouldn't accept without evidence.
If this were really in the range of statistically expected outcomes, then a) there should have been a plan in place to fix it before the structure went up, and b) they would have had sufficient insurance coverage to pay for the fix. Neither is true. The ongoing gosh-golly-who-cooda-node routine plus the simultaneous festival of blame-shifting suggests to me that, at best, the business side of the operation went well beyond what an engineer would have done in the same place.
The correct fix to the building code here I'm happy to leave to the experts, just as long as they eliminate outcomes like this. If that ends up raising the costs for other fancy buildings stuffed with pied-a-terres for the wealthy even to prohibitive levels, I am entirely fine with that. Erring on the side of of earthquake safety while building near major faults in major metropolitan areas seems like a great choice to me.
I guess the point I'm trying to make is that complete elimination isn't possible in a long tail statistical distribution. There will always be a point where we have to draw the line, and there will always be freak occurrences of undesirable outcomes. This is the crux of engineering - finding the correct balance between cost and safety. Perhaps the current state is not enough, but the wildly disproportionate amount of structures that are working just fine tells me we are close.
> If that ends up raising the costs for other fancy buildings stuffed with pied-a-terres for the wealthy even to prohibitive levels, I am entirely fine with that.
Building codes aren't only applied to high end buildings. Any changes affect the (badly needed) low end housing just as much as high end buildings. Just another thing to consider.
> Erring on the side of of earthquake safety while building near major faults in major metropolitan areas seems like a great choice to me.
No disagreement there ;)
Medical care has a much longer tail, for example, but many countries manage to provide full financial coverage and individual support in treating and managing even very rare diseases.
If you're saying this was a reasonably forseeable but unlikely outcome of cost-driven skipping out on the bedrock anchoring that neighboring buildings used, the I don't think it's too much to ask them to have an answer to the question of, "Ok, if your cheap solution doesn't work, what will you do next?" And if they don't have a good answer to that, I also don't think it's too much for them to not be allowed to build the thing.
Now that would be a serious problem.
Perhaps, but have you compared it to the building code in Japan? I personally have qualifications in this area so I'm just asking.
Do you have anything else to say besides vague claims on your credentials and experience?
In reality many more will collapse, because some buildings are older and not up to code, as well as earthquakes generally just being weird and unpredictable.
Do you think 10% of buildings collapsing is a "loose" or "tight" code? 10% losses is acceptable in say, human habitation?
You don't get exactly 10% failure rate, you have to demonstrate better than 10% failure rate which means going past that point. Further, failure is not 'collapse' failure is anyone in the building being unable to exit safely.
And again, they are aiming for a 9.0 that's a ridiculously large earthquake. An 7.8 similar to the last SF earthquake would still be a major earthquake, but vastly less dangerous by comparison.
I realize the focus of the article is SF, but when the author elaborates on our lack of experience with skyscrapers in earthquakes, with no mention at all of Japan, it makes me think that this is just a clueless scare piece rather than any kind of thoughtful analysis.
Then, in the article, I read about San Fransisco:
"the issue of seismic safety of high rises was “never a factor” in the redevelopment plans"
I can not imagine any positive outcome here.
It's unclear from your comment, so I wanted to clarify for other people who may not know: skyscrapers are intentionally built such that they sway, as that helps to disperse the energy more than a rigid structure.
There are entire careers dedicated to determine buildings ability to survive natural disasters and informing people about the risk. There are entire careers dedicated to finding ways to make buildings more earth quake resistant. It seems like banks, developers, governments, and insurance companies would be listening to both of these professionals very closely before building something one thousand feet high. I would prefer to hear from them than Thomas Fuller of the New York Times.
It's about 18 hours of training on disaster preparedness, earthquake safety, triage, and search and rescue. The idea is twofold - the more citizens that can handle themselves and their families for the first 72 hours of a disaster, the more people that have a 72 hour timeline to death (trapped, injured) the professionals can find and rescue.
The second is that there is literally no city in the world that has the fire department resources to handle a catastrophic disaster (>8 earthquake, tsunami) without "significant loss," and so trained volunteers can do a great deal to "fill the gap."
In the 1989 earthquake untrained volunteers were critical in helping the SFFD get water into hoses  when the mains went down. Last count I heard is that there's about 2,000 NERTs now trained in the city. Imagine having 2,000 basic-trained volunteers helping out in a disaster. Incredible. To put it in perspective, there's only about 1,500 employees of the SFFD.
There's a city-wide drill this weekend, actually, and they need victim volunteers. If you want to get painted with gruesome injuries and scream at people in green hardhats, it could make for a great time! 
If you aren't in the bay area, check out the FEMA equivalent, "CERT." 
edit- by the way, this training is free, and comes at no obligation to actually run into burning buildings should a disaster happen (they want you to take care of your home, family, and neighbors before anything else)
“Ten percent of buildings will collapse,” said Lucy Jones, the former leader of natural hazards research at the United States Geological Survey who is leading a campaign to make building codes in California stronger. “I don’t understand why that’s acceptable.”"
One way that reads to me is that an event over some threshold has a high probability to cause the complete collapse all of those buildings. 90% doesn't seem like a very high threshold either, if it corresponds straight out to a 1-in-10 event that seems quite bad. If it's a 90% chance of survival in a 1-in-100 event, that's better, but not great.
what happens afterwards? is the building supposed to be torn down?
If there is a 10% chance of collapse every 2475 years, that is ~1.1/10million per day chance, or 0.11 micromorts. That assumes 100% death during a collapse, and that the person spends all day in one of these buildings.
0.11 micromorts/day is very low, which makes the design criteria reasonable. Of course, I suspect our ability to predict infrequent events with any degree of accuracy is unlikely.
This gets you into that domain where most people really don't like to go, but... you don't get the choice of 100% perfectly likely to stand up, so where do you draw the line? You don't have an alternative. A line will be drawn. If you don't draw one deliberately, you'll draw one accidentally.
But if you want to have some fun with ways the probability estimates could be badly broken, correlated failures can be the way to go. Suppose for the sake of argument that there is an earthquake in the future that if each building was subjected to it individually would cause 10% of the buildings to come down. That doesn't mean that 10% of the buildings will fall down in real life, though, because the failures could be correlated and coupled, if one building falling down makes another building falling down more likely.
If I'm running the physics and numbers in my head correctly , even in an extremely large earthquake the Hollywood image of buildings toppling each other like dominos is still exceedingly unlikely. They'll go down, not sideways. But the additional shocks they create in both the air and the ground in the process could tip some other buildings over the edge. We know from 9/11 that buildings going down can seriously damage other nearby buildings.
So, densely packing buildings with a 90% survival rate can result in a net survival rate less than 90%.
And of course, if it's 90% at Richter x, there's no law of the universe that says x is the limit. x+1.5 is still perfectly possible.
: It's hard to google up the amplitude of an earthquake in a distance measure, rather than Richter scale or something. But it looks like "several centimeters" of transverse motion would be a very large earthquake, which isn't going to put the center of mass of a building out of the area described by its foundations. Which isn't anywhere near a complete description of what it would take to tip a building like a domino, but is enough to say it's a long way from happening.
(My guess is that it's actually impossible to tip a tall building like a domino as any possible attempt to exert the forces necessary to do so would itself be enough to destroy the building. See also "why Superman must also be telekinetic", because it doesn't matter how strong you make an 747, there is no place on that plane it can be picked up by any amount of pressure exerted by two human-sized hands without the hands tearing right through the plane, rather than nicely carrying it. (A handful of non-telekinetic Supermans could do it if the plane lowers the landing gear and Supermans support the tires with their backs instead, but that'll be tricky to "fly" in other ways. Especially since the best way to support the plane will be with the Supermans being sideways, to maximize area of contact with the tire.) Similarly, some sort of Superman-esque force that applies equally to all atoms would be required, rather than the real forces we can apply via external pressures.)
Here’s an article about what they did. (Skip the fluff in first third, it does get down to details later.)
But what's weird, IMO, is that some of the shorter highrises like the Millennium Tower were approved to be built not anchored, but on pylons floating in the soil layer:
I mean, sure, as long as things are stable, the weight of the building will keep it in place. But I don't think anyone knows how the soft layer underneath most of SOMA will behave, when a big earthquake comes. People know it will undergo liquification, but by how much, and what will it do to buildings on "floating" foundations, that's not certain...
That the Millennium Tower is sinking asymmetrically doesn't necessarily mean the design was flawed, even in a high-risk earthquake zone. It could be flawed, but the very fact that it's sinking doesn't tell us that. It could merely be that out of the hundreds of towers constructed globally each year, Millennium Tower was the unlucky outlier which defied the otherwise carefully weighed odds.
The sinking does seem like a concern and is no doubt related. It seems like someone underestimated how much foundation work would be needed on that building.
How does the front door work? Do they have steps down into the lobby now?
I'm pretty sure the building would have lost structural integrity from the force applied by gravity before the lean can reach 30 feet.
That's very rough of course. Many bad things could happen much earlier, such as unexpected forces causing structural damage.
Note also that the WTC didn't exactly "fall over". It collapsed on itself.
The WTC did not fall over.
"one out of every four buildings in the Bay Area might not be usable after a magnitude 7 earthquake"
"At a time when the average price of a home in San Francisco is above $1.2 million..."
Why aren't people pricing in an earthquake discount? This is so totally irrational, housing in SF should be cheaper given the certain risk of an earthquake and consequent large probability of severe damage. And even if your house isn't destroyed, good luck finding a contractor post-earthquake. Even now contractors are so hard to find, over priced, and many do shoddy work, I can't imagine why people don't see this coming and stop paying this much for something that may fall down any day now.
Similarly why we continue to build in floodplains, it's usually fine and when it's not the Federal government steps in and makes sure people are bailed out. This has proven to be a good strategy as long as you're not in Puerto Rico. It's the same idea as the "Greenspan put" being priced into the financial markets.
This may be a conservative talking point but it seems more likely that such disasters happen on timescales humans aren't built to reason about. Even if there were no bailouts I doubt things would be any different. These areas have desirable attributes that make them attractive regardless of the risk. There are also precious few areas not subject to any risk at all (a large portion of the continental USA is subject to hurricanes, tornadoes, earthquakes, blizzards, or other potential disasters).
Because it's a matter of insurance, and thus reduced to a recurring premium bill.
Why not price all maintenance costs and electricity too? Living in this house for the next fifty years will cost you all these utility bills; you should get a discount from the purchase price to reflect that! :)
I still want to know why people aren't thinking about this when they pay so much for a house.
Like all insurance, the price reflects the risk vs the number of buyers. If more people had it, the price would be less exorbitant.
The question is why don't the insurance people work a bit harder to broaden the coverage; they could make more money even at a lower price point.
Perhaps, those who are not covered are too resistant; they are not willing to get the coverage even at a reasonable price because of the way they perceive the risk/benefit. So that is to say, maybe it's a "hard sell".
The Citigroup building in NYC had a fundamental design flaw that could cause it to collapse.
I'm not sure how you'd prevent water & sewer lines from breaking during an earthquake - they're surrounded by earth (or secured along concrete walls in buried vaults) so they're going to get motion & shear all along their length - so not much room to flex. Assuming they were made of a flexible material and not cast iron.
One of the reasons why the 1906 earthquake was so devastating were the fires afterwards, where the fire companies couldn't get water.
> The upper zone of the AWSS, however, functioned normally through the earthquake period, and was used to suppress earthquake-caused fires.
Looks like they're building more: http://abc7news.com/news/over-30-cisterns-to-be-built-in-sf-...
I wonder with human population increasing and with the shortage of urban land needing highrises, what is the long term solution to this.
From http://mkaku.org/home/articles/the-physics-of-extraterrestri... :
"For example, a Type I civilization is a truly planetary one, which has mastered most forms of planetary energy. Their energy output may be on the order of thousands to millions of times our current planetary output. Mark Twain once said, ”Everyone complains about the weather, but no one does anything about it.“ This may change with a Type I civilization, which has enough energy to modify the weather. They also have enough energy to alter the course of earthquakes, volcanoes, and build cities on their oceans."
I'm not sure what this. Guessing maybe 120 feet, e.g., gives a tilt of 180/pi * arctan(14/12/120) = 0.56 degrees.
The maximum slope b=rise/run compatible with this is b_max = (314 mm/3m)/F_L = .105/F_L ~ 0.005 for F_L = 20,
which corresponds to 0.005 radians = 0.3 degrees.
Projects like roller rinks and warehouses that use air pallets require more level floors, but typically only by a factor of 2 .
There is no comparison with building codes of other countries which are earthquake prone (such as JP or TW), only example is provided (Millennium Tower) and it is unclear if liquifaction will only affect skyscrapers or 1-2 storey buildings too.
That statement really boggles the mind.
How do you own some of the most valuable property in the world, and not maintain it in the simplest of ways against something that could literally destroy your investment? After 24 years of knowing that your building was in danger?
> The damper system has no connection with the seismic safety of One Rincon. It is always a challenge to build a tall structure in earthquake country, and One Rincon's engineering response was to use outriggers, tall reinforced concrete columns built around the core of the building.
Surely that’s a typo? Because that is kind of insane.
Example article I found: https://recklesslyoptimistic.com/san-franciscos-height-restr...
There are probably more height restrictions in different areas, and a 500 foot limit is actually quite restrictive. It would have prevented Salesforce Tower. The Empire State Building is over 100 floors.
Don't live in New York or Chicago because cold.
Don't live in Seattle because rain.
Don't live in Taipei because earthquakes and a bunch of cruise missiles pointed at it.
Don't live in Seoul because artillery and a dictator across the street.
Don't live in Miami because hurricanes.
Don't live in Madison, WI because tornadoes.
Don't live in Hill Country because ambulance will take 20 minutes to get to you when you step on a rusty barn nail.
Some people will take death over ever having to shovel again.
is that bad? it's not like you're going to die from tetanus in 20min.
SFFD has a 6 minute response rate within San Francisco.
I had to integrate our existing Django based system with Salesforce. What I expected to take a few days took a few months. Similar syncing of data between another Django based system did take a couple of days.
I can't go on, it brings back too many bad memories.
If you have ever enjoyed development you will hate Salesforce. It feels like the tech equivalent of digging holes and filling them back in again.
No matter how strong the building is if the ground gives up it must fall over.
Shockingly, the people who own property less likely to collapse in an earthquake do not want big buildings next door. So big buildings are being built on harbor fill. What could go wrong?
Depending on how deep the liquefaction-prone layers go, that's could be an option that's realistic only for a high rise.
What if high rise building is anchored through all liquefaction-prone layers but the layers start to shift (they are on slight incline) when they get liquified? I am not expert but I can imagine it is possible that, if the structural support is long enough, just few inches of lateral movement may completely compromise the support.
They would be having problems if they did it the right way.
Given factors extracted by us, to get the full picture you may use open source catastrophe modelling software, Hazus released by FEMA.