. >> reporter: frank wolo has been designing buildings to compensate for that. parts of selma along the embarcadero are still slowly sinking and sections of the former mission bay have settled 9 feet. some high rises along the former shoreline sunk over the years including the former pg & e headquarters and the standard oil building. the new transbay terminal project at third and fremont is also on bay mud. before crews can everyone begin building they must shore up tons of mud and pump up bay water. engineers keep a close eye. >> if there's slight movement occurring but we know why it's happening, is that movement going to be detriplet -- detrimental to the building. >> and? >> it's not. >> we swayed, it felt like two or three inches back and forth. >> you could also kind of hear the iron, the metal kind of moving. >> reporter: frank willow says those high rises are safe and will support it but one place you would not be standing in the middle of an earthquake is here. after the 1906 quake this entire area was one giant sink hole. >> we know that area all liqui