earthquakes are there per year above 8.0? >> one per year. this should be our only one. we talked about the 6. 2 after shocks. there's a significant chance of at least a 7 or greater after shock. so if there's a 9 earthquake, there could be an 8 after shock. if there's a 6, there could be a 5. we go one full order down the line. so i think there's going to be much more shaking tonight. some of these buildings were already cracked. that's why they don't want to be in the way of these cracked buildings if another 7.0 continues to shake that structure. >> we're joined by david gallo and cnn's safety analysis david soucie. david gallo, just realistically, if what they've seen this far this afternoon, they've seen six-foot waves, they're keeping these warnings in effect out of