unreinforced masonry building. safe building or not such a safe building? not safe at all. you have deep set windows, arched windows, metal plate, then we can work. weak morter, what is that? brick on top of brick on top of brick. there's an ample of the header row, you see how they are turned perpendicular to each other, you can see the header rows in this one, see the brick going the other way about every 5 or 7 rows. deep set windows. here's a close up of one of those plates. a parapet wall is a clue that this building is an unreinforced building. which direction can that building go? right back out. this building, brick or wood? what are some of the clues? okay, what are the windows? they are deep set. there's a clue right there. deep set. deep set window, unreinforced masonry. can you see the metal plates? there is a metal plate right over there in the corner, there's another one over there. hard to see. also has a parapet on it. deep set windows. even though it has stucco on it, don't be fooled that that's wood up above. it's all brick because it's deep set windows. h

>> i want to point out the building here at 660 mission street, which i believe is an unreinforced masonry buildingetrofitted, seismically upgraded. once it is seismically upgraded, it is safe, right? >> when you seismically upgrade it, it is to a standard it doesn't collapse, but it may not be reusable or repairable. >> it was an economic decision of how much money the city could afford versus the benefits to retrofit the buildings. >> we have done about 90% of the upgrade. the standard is low enough that in a major upgrade most will have to be replaced and we lose these beautiful buildings. many of the details are not what they appear to be. these are sheet metal details and trims. sheet metal cornices. san francisco was famous for the sheet metal work. when you go into the sheet metal shop, the whole front of the building is made of sheet metal. that is pacific? no, powell. >> i trick on how you can date old brick buildings, after the '06 earthquake they made windows with steel plates. before that earthquake if you see an arch, it is a pre '06. it is an easy way to date the buildings. >> you can

>> you have to think that many, many buildings if not all back east are unreinforced masonry so when it shook, it really was scary, i'm sure. >> reporter: it was the strongest never that area so they aren't used to it. >> the other thing is, too, look at the date. we are closing to september 11th the 10-year anniversary. new york, an earthquake is not my first thought. >> reporter: a lot of people thought it was a terrorist attack. they evacuated the pentagon. they didn't know what's going on. >> it's a big wake-up caught for earthquake preparedness like we have. >> reporter: then we'll start doing our hurricane and tornado preparedness. >> break it loose. >> cellars. >>> thank you. >>> libyan rebels have taken over moammar qaddafi's compound. the libyan leader still hasn't been captured but rebel troops are claiming a major victory. charlie d'agata on this major milestone of the libyan uprising. >>> reporter: rebels surrounded moammar qaddafi's compound in tripoli and opened fire. but troops loyal to the libyan leader aren't going to give up without a fight. rebels took cover trying

>> certainly to unreinforced masonry and brick structures we can see falling chimneys. structural damage to buildings. an earthquake this size on the eastern seaboard should be widely felt throughout much of the eastern united states and canada. megyn: can you expand on that in terms of beyond the buildings, do you typically see what minor scratch injuries, head bumps in. >> in terms of injury, people -- injuries will pry barely be from collapsed structures which i haven't heard of any reports on or following -- falling obts could be brick from your chimney or things falling off the shelves and other things like that. megyn: can you explain the different reports we have been getting on 5 dallas 8 magnitude. 5.9 seems to be where we settinged. . megyn: the latest we heard is 5.9. how significant is the difference between 5.or 5.8. >> not a lot in this area. 5.8 to 5.9, it will be widely felt and can do dmajt local area around northern virginia. megyn: we were talking about now the folk out west are a little bit more prepared. this is video from downtown new york from folks outside of the buildings tha