joining me geophysical assist don blakeman, works in denver. are 100 aftershocks normal after quakes like this? >> very normal. depends what size of aftershocks you're looking at. more and more, good family, large aftershock. >> after this weekend's activity, are you any closer to being able to predict what might happen next? >> we can't predict in the sense of identifying where, when, and how large quakes are in a particular area, we simply don't have the science to do that. we can tell you typically get a quake like this, shallow like most quakes are, california quakes. when you get a quake like that, we expect aftershock exactly like we're seeing right now. >> how long does that last? >> any particular aftershock, we know we'll have more of these. >> aftershocks, does that do over a period of hours or days? >> it depends on the quakes. typically the aftershocks last much longer the larger the quake is. in this case i would say it probably definitely would be days and probably stretch into weeks. but as time goes by, less and less aftershocks