liquefaction, liquefaction is a term they use when the ground is loose. usually when structures or infrastructure is built on sand or land fill, something that's not solid, what happens is in shaking, during an earthquake, the earth that's very loose, that sand or land fill, acts like water. this is sand, sand and water coming up through a hole. in japan, all these buildings were built on liquefaction. i forget what year this was, but it was one of the bigger earthquakes. 7 story buildings built on liquefaction. the amount of time the earth shook, the earth became liquid and as it became liquid, the building sank into it until it stopped. when it stopped it just fell over. light damage buildings, superficial damage, broken windows, some plaster that might be cracked but basically a light damage building would be one that has mostly damage to the contents. shelves falling over, windows broken, that type of thing. if you had to go into a light damaged building, you would use these procedures. of course you gather information about a building before you go i

it is all sold and liquefaction. >> treasure island is unique. it was originally developed to be the location of the world fair with the understanding that once it was finished, that would become the location of san francisco international airport. it is 11,000 feet long. in those days, the thought that was more than enough to land any conceivable airplane. they thought it was ideal. they said that we have all kinds of sand out in the bay from the sacramento river. we will take the stand out of the bay and create this island. the sand is loose and below the water. it liquefied in 1957. it liquefied in 1989 during the loma prieta. it was similar to what happened in the marina. >> as they move along and developed treasure island, the developer also has to provide stabilization programs. >> the sand has to be strengthened so that it will not liquefy. the buildings have to gain support below the sand in more confident material. >> we were talking about the waterfront. here's the very building. here is the intersection of the water and the land. the a

the most dramatic, to me, was what they called sand blows or liquefaction back -- liquefaction.like geysers that shot up two stories in the air. the biggest pocket of those was actually a round 10-mile bell which is right were the charleston international airport yesterday. >> hundreds of feet long fishes were breaking open in the ground. railroad trains are being toppled. major damage all around the area. surprisingly not that many people killed. probably 60's some bad night. eventually more than 100. the numbers are a little they because a lot of people, the records never quite came in. over 100 people killed. >> a huge international story. people seem to have sort of forgotten about this disaster in the wake of the san francisco earthquake in 1906 exactly 20 years later, but it was truly an earthquake that had implications across the united states and west -- got international news. it was a big story. >> hata this city respond? what did they do? >> for a long time didn't know what to do. the city council did not be for days. everybody that night fled from their houses, went

there was a lot of water damage we might have even had some liquefaction soil failure. we had a major failure. >> that's right. this tribute goes all the way to golden gate. this is in a mountain lake and beyond ththat, it was a surface flow. this is a reservoir. on my right is this defensive the positive dune sand. the wind blows, it comes from the ocean beach. because the sand is moving, you can see evidence along this side of the hill in 1989. the vibrations in accelerated. you have a significant amount of movement to the point that the homes that uc had very severe damage for two blocks. we recognized what the problem was at the time, it was a matter of loose sand on a very steep slope. thank you for the effort. we were able to get federal funding and design which you see in the upper walls. the lower walls was actually billed as part of the wpa. the upper wall was built in 1991-'92. this is a concrete wall and it has rocked going through the wall that extends the distance of 80 feet beyond the wall. the next earthquake occurs, the wall is designed to resist and the

it not only has liquefaction, but it also has a hillside stability issues. while it may be stable sporadically, when the earthquake comes, the slopes may fail. as a minimum, they should retain the services of a geotechnical and structural engineer, and there are well qualified people who come out. i am not just talking about and inspection service, i'm talking that licensed engineer, geotechnical, to look around, look at the maps available, and write an opinion letter as to the adequacy of the structure or the soil. there is another thing to consider when you are buying and building to the east of the van ness ave. a third map. this map depicts the area of the fire that followed the 1906 earthquake. the blue is where all the buildings were destroyed or badly damaged by the fire. as a result, the ashes from those fires remained on site. in those days, lead paint was used to paint the sides of buildings. it is a known carcinogen. it is a hazardous material. what they did was after the earthquake, they took these mounds of sand, the valencia st. hill, if you go

improvements, and some additions were made to the project to address some of vulnerability in addition to liquefaction. we also note it is also possible additional pipeline work will need to be required in the city, but that has yet to be verified. veep improvements that we know are needed to increase -- improvements that we know are needed to increase reliability, if more work is found to be required to meet the goals, that work would be done as part of the ongoing water enterprise cip. questions have been raised whether changes we're asking you to approve would impede our ability to meet goals, in particular those associated with water supply. in short, there is nothing from today's action that should affect water supply goals or our commitment to meet these goals. however, we also reported to you that in order for us to participate in our larger projects, we have had to provide more flows for releases, and that makes meeting the water supply goal more difficult. you requested that we come back to you by the end of august and report back on progress towards meeting the water supply goals, and staff

the most dramatic to me were the what they called the fan blows or liquefaction factors, geysers that shot up as much as two stories in the air. and the biggest pocket of those was actually around ten mile hill which is right near where the charleston international airport is today. >> fissures hundreds of feet long were breaking open in the ground, railroad trains were being toppled, um, major damage all around the area. and surprisingly, not that many people killed. probably 60 some that night, eventually more than 100. the numbers are a little vague because a lot of people the records never quite came in the. but over 100 people killed. >> it's a huge international story. people seem to have sort of forgotten about this disaster in the wake of the san francisco earthquake in 1906, exactly 20 years later. but it was truly an earthquake that had implications across the united states and was national, international news. it was a big story. >> how did the city respond? what did they do? >> for a long time they didn't know what to do. the city council didn't meet for days. everybody th