tv [untitled] December 2, 2013 8:00am-8:31am PST
landslide areas. all the green areas are potentially liquifiable. if pat says, you are going to have.9 g. you could have substantial amp liification of this. this fascinating old map from the 1800's. it shows what san francisco looked like before a lot of it was filled. this is the mission district, the marsh of mission bay went all the way up to 7th and mission. that's how big the marsh is. the bay went up to montgomery street. so all this is bay. all this is bay. all this is bay.
do you see these city streets out here? this is a small section of the city. this has all been filled. >> if you look at this map was recently adopted by the state, as their hazhard map. that's what these green areas are. just enormous mission area. >> this is an interesting tid bit. most people don't realize. there was a creek that flowed out of a lake in the mission. the lake was three city blocks large. it was at 17th and valencia. there's a plaque out there. you could sail a boat up the creek that flowed out into the bay into the lake at 7 the and mission and go sailing. it was that big. that land was so valuable because everybody wanted to
live east of twin peaks because the weather was better here. warm. they filled in as much land as they probably could. and then they were forceed to building on the other side of twin peaks. where the weather wasn't as nice. >> i live in inner sunset. in 1906. in the big earthquake, that area had dramatic effect. one building settled down into the lake bed. >> the largest loss of life was at 17th and valencia hotel. the fire department came in, drown the people in the basement and the fire came and killed a bunch more people. across the street, there was a
3 story building any after the earthquake, the first floor went straight down. didn't crush. just liquified and created 1 story basement. >> we have unusual soil conditions and then, on top of that, we have built environment. we have buildings built of all different kinds of construction types and dates. when you put those together. maybe you are sitting on rock areas that are built solidly that will have little impact and you have other buildings, soft story buildings and people have essentially the same
expectation. >> and the building department would come knock on my door and tell me it wasn't safe >> there are very few retrofitted laws. you have to make brick buildings saver. >> you have to reduce the risk of life lost. >> so the brick building standard is a low standard. it was to prevent catastrophic collapse. the brick buildings, we have 1800 of them. most have been upgraded to prevent catastrophic deaths. it's the lowest possible >> and they might need to be
torn john. by the way, this was lori johnson. this is our risk analysis and has done work to reconstruction especiallily in kobe and post katrina. >> thanks for joining us >> you are going to be coming to the caps meeting. >> i am on the advisory committee. >> most of san francisco of densely built and not very tall. >> what is the relationship of hazard between large buildings and the typical san francisco low rise? >> most large buildings are structural steel buildings and they do well in earthquakes. there's a class there were popular in the 50's and 60's,
there's a lot of apartment buildings, about 10 or 15 story tall. they are the worst class to be in. those midrise buildings >> how many of those do you think there are? >> about 500 plus or minus 200. >> we have seen how they perform. for example, in mexico city. >> they look like stacks of pan cakes. they built row after row of these concrete buildings and mexico city is built around an island in the middle and a big lake and they filled it in, just like san francisco. the floors were stacked like this. it looked like a stack of pan
cakes. >> how did this compare older buildings of the 1920's or 30's? >> they will have more reenforcing in them. they had a tendency to use more round columns with spiral hoops. they don't necessarily catastrophicly collapse. in a perverse sense, the 50's and 60's buildings, you don't want to be in. i am in a 1920 building >> i wanted to clarify, we have beautiful, very ornate buildings they are taller.
a lot of apartment buildings. >> those are mostly steel framed buildings. in the 50's and 60's, they wanted to create open floor spaces and they went to concrete spaces and thought it was great until the san fernando earthquake and the earthquake came and the building disappeared. they said, oops and changed the code immediately. >> we look at it and say, it didn't do what we thought. the codes are rarely
perspective. how can we make that happen? they wait for a catastrophe and then change it >> just to clarify. we don't have instrumentation to record the shaking and to do a computer simulation is difficult to do without the data. we only learn through events. not all the records we have are indicative of how every earthquake shaking event will be like. >> we have recently amended the code to have instruments in them so we can record and how
much the earth has moved. that's terrific. not many existing buildings are instrumented. one the things we will look at, at the caps program is to retrofit them. we can look at other after earthquakes. it had similar types of faults we have here. there are a lot of similarities. >> there is something, of the type of construction. there are debate about how they will perform. we know how soil conditions will affect. how good your building is, is
going to be predominated by soil conditions. if you put 3 engineers in the room, you get 5 opinions. there are buildings that engineers can look at and agree there's not a chance in hell it will survive. there are buildings where there's no reasonable belief, matter of fact, we would be shocked the building would still be standing in an earthquake. >> the after earthquakes that are common and then we have the design earthquakes that we use to think about what is the reasonable earthquake and then we have the maximum possible earthquake, like the 1906. >> 500-year retu6-cycle.
>> i take it back. most wood frame buildings, probably pre-existed before code >> which was in the early 70's? >> they had requirements in the 50's and 60's. we don't consider building code until 1973. major buildings, was designed by a genious and it was ahead of the time. they required an engineer. smaller buildings, you didn't need an engineer on all of them. >> basically, if your building was built before early 70's. it's likely to have some earthquake resistance and resilience of the cost of construction. it wasn't specifically designed to with with stand and
earthquake. >> most of the sun stream homes. these are track homes, mostly built to speck homes. built the way they always built. they have a degree of earthquake resistance. >> they have a tendency to pound together and the buildings in the middle survive because the earthquake isn't long enough. the individual at the end of the block is like the book at the end of shelf. they fall over and the next one falls over. >> in the marina. we saw corner believes collapse. >> there are 2 ways to look at earthquakes. i think each one of us wants to know how our house, where we live is going to perform. we also need to look at how the city is going to perform. pat makes a good point, most
the newer buildings will perform better. keep in mind, the studies we have done certainly show is that most the vulnerable buildings will be residential. half of the residential units were built before world war ii. we have a very old housing stock. we have the oldest housing stock this side of mississippi. and that's where our problems are most likely to be. >> i going to test the microphone and ask people how you expect your home to perform. >> anybody who wants to share. tell us, what kind of building. do you live in a wood frame >> yes >> after a major earthquake. what's your expectation.
>> i am afraid from last year's earthquake class, you mentioned. the house might pop to the street because my garage is empty. >> is it in the middle of the block? >> middle. >> there's less chance. sir, what kind of building do you live in? >> i live in an apartment if ground floor parking. >> in the middle of the block, corner. >> corner. >> are there openings on both sides? >> yes. on both sides. >> it's a wood framed building? >> it seems to be a hybrid.
with concrete and steel and wood frame on top of that. >> we don't often see that. modern buildings have a podium. >> what neighborhood are you in >> dolores park. >> you will hit the lake. if are in the dolores, you are in pretty good shape. >> what is your expectation of what your building is going to be like after a major earthquake? >> i am really not sure. that's my concern. >> i see. this gentlemen is correct. his concern is his building. you have to look at it block by block. you can see that the edges of the fill area vary block by
block. let me point out in cole valley, there was an old pond and an amusement park with a trolley. that pond was filled in, that's a potential liquify site. so we have to look at the soil. >> there are area that is are fascinating. westportal, there was a creek that flowed all the way down to pig lake. i think that's what the spanish called it. there was a deep ravine. they filled it in with the tunnel muck and they filled in
the ravine and built houses. the other area is really interesting, down 18th street. there was a creek coming from eureka. there is a street called pond. it's not a coincidence. >> part of what we're going too try to do is update this map and give it historical data. there are more significant data. >> how do you know if your individual lot? >> one is these lines are very clearly defined as boundaries. they don't actually mean, this is the exact edge. you could be on one side or the
other. it's not okay here and not okay 10 feet away. but, on the other hand, we have taken this map, which was published by the state and digitized it so if any portion lies within these zones. if you tell me your address, i can tell you whether you lie it in. >> there's a book. >> 558-6205 and the clerk or me will take the book and look it up and say, yes, you lie within a particular zone >> i am the manager of a large condo minnium project. it was built in 1963. it's steel and concrete >> there's a difference between
structural steel and rebarb. >> it's steel columns. thank you goodness. >> 19 stories and i live across the street in a building that was built i believe in 1920 and i brought my staff here because we want to, as a team, be prepared with our building and the owners who live there. >> so her question is, how can someone find out what they should be prepared for? >> the first thing is to see if the there are original plans for their building >> should they hire someone >> someone need to verify if you are structural steel frame. there's a high likelihood
there's a plan. if you are a concrete frame, you have a set of concerns. >> the first thing, i recommend everybody do this. get a complete set of documents for your building from accessor's office and other office in a city and put them in a notebook and you have all your documents. here, you can ask to get all the permits, plans, job cards, sign off sheets. special inspection. get everything. there's no reason why the city should be a source of this. then, if you ever want to be a building expansion, you have the documents. you can have that done as well. >> you said something about getting plans for your building. what if you are in one of the
50 percent that were built a long time ago? i have a 1903 building >> most the plans and permits for pre-1906 were destroyed in the fire. except for the larger buildings. many of the plans are available in berkeley. most of those were destroyed. >> there's not much there. >> you can also go back and get original water department records >> actually, the story is, the city had 2 water companies that were privately owned.
spring valley and another one. their headquarters were at crystal springs. that was actually the ceo. he wanted to build his house. their stuff was held outside of the city. after the 06 earthquake, one of the reports by the city was, all the fire hydrants were tied to spring valley. the city said this is crazy. they actually put in a second war supply and municipalized. all the records were transferred to the water
department, they are at 1155 market and they are all the way back to 1868. it will be $0.37 to hook up with your water >> also on your question, the cost in having a structural engineer take a look at your building is a very, very small percentage of the building's value. i think whether we have a large condominium, your building is static and the type of soil you're silting on and certain types of deterioration, and once you have that inspection done, you will sleep much
better and make rational decisions on how you want to priorityize. >> i totally agree with you, the plans are part of the history. would i be able to get them? >> they have the water hook up and the date your building was legalized. >> if it's an apartment building, most engineers know where you are in the soil conditions and can give you an expectation of the performance. most wood frame believes do well on the first, second and third floors. the upper stores act as a rigid block. but the garage level is an open
floor plate. the total drift is a thing you can look at without paying too much attention. if the building is stiff. instead of it being uniform, can all be forced to that lowest story. you are standing there and someone knocks your knees out and you fall down. that's what can happen to soft story buildings. >> i think a lot of us don't pay enough attention to the nonstructural damage. here we are in this room, nonstructural damage can be to
the sealing, so here's a story. in the 1989 earthquake, that's the day the marriott hotel opened. it has that little bar at the top. up at the top of building, it swayed back and forth and the ceiling planes shaved off a sprinkler and it flooded the top floor. >> it's a big problem. in north ridge, it was a huge problem. there was tremendous losses because your shoot rock gets wet. it's like having a flood. we are on a group trying to look at all the issue in san
francisco and make recommendations. whether it responds and does well. the subsequent issue is fire, which we haven't talked about here. with fire goes gas line breaks and water line breaks not being able to protect the structure once it happens. all those utility things come into play. as a homeowner's association, you have to anticipate as a resident of san francisco, there's going to be a lot of ground deformation and our utilities will have problems. we recently had window storms and while pg and e has done a wonderful job, there will be
breaks. you will be able to camp in your argument. it would be like you went away for a long time for a camping trip. you will be able to change the thinking about where people go. one of the big issues in katrina, people were forceed to evacuate. if we had a large fire. we might have to force an evacuation. >> one the things we're trying to develop is an expectation, this is our bottom line expectation for building performance. your building, while it might not be damaged. will it be sufficient to camp out it? >> we are not quite there yet.
>> that's the kind of expectation. >> i think we should pass this along to the audience. there should be design standards. there's a discussion, what should our design standards be for new construction? and the building department, we on caps are going to say, what standards should those be? and there's a group of us that have come up with a concept that hasn't been universally adopted of at some point in the future, this might be 15, 20, 25 years out, where our retrofits and our renovations are implemented at that point. it's not going to happen within next week. but wher