walter hayes, world renowned seismologist, is on the phone with us right now. mr.ank you for being with us. when you heard about this 6.1 magnitude quake in california, what was your first thought? >> california's been overdue for such an earthquake for quite a while, so it's not a big surprise in the statistical sense. >> you are the third or fourth person this morning who said california has been overdue. how often would you anticipate an earthquake there? >> the statistic is every ten years you'll have three of this size. we have not had three of this size in the last ten years. it's been since 1994, the north ridge earthquake, that we really had a significant earthquake in california, so that's the reason people say it's overdue. >> what kind of aftershocks do you think they should expect? while we were there, we were on the phone with janet upton and she was feeling one as we spoke. >> kind of the rule of thumb if it's a magnitude 6.1, you'll have ten 5.1s, not exactly ten but the range of ten, 100 4.1s, now the 4.1s and 5.1s are not that damaging unless they'

joining me on the telephone seismologist as well as director of global alliance for reduction, walter hayes. can you put this quake into context in terms of size. 29 years ago since a 6.9 earthquake caused so much damage in san francisco. this is 6.1 on the richter scale nearly one-tenth the power? >> that is the confusion. it is nearly 30 times weaker. >> because it is both amplitude and energy. it is the wave motion of the quake, is that right? the ground shaking? >> they use the waves to determine the magnitude number. the magnitude number is a measure of the energy released. it was nearly 30 times more energy than this one. it would take 30 of these to equal one. >> this is still causing and we are seeing live pictures, walls that have collapsed. there are homes on fire. that is still even at 6.1 we are getting an update now that estimate is lowered to 6.0. this is still a large earthquake. you only have 100 or so higher earthquakes per year. >> around the world. one magnitude eight, ten sevens. california doesn't always get its share of them. other parts of the world get the share. thi