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