i'm here with peggy hellwig who is operations manager. first of all, what is earthquake early warning? what is earthquake early warning? this is animation running in realtime. it is going to show a magnitude eight earthquake. it is the same as the 1906 earthquake that we heard about. the distances this this earthquake is starting at the top of the an san andreas fault and is going to rupture its way down to stran. that's what the gray -- this laser is much use. but this is what the brown is. this is the rupture coming down the fault to san francisco. as it goes, it raidiates energy and p waves and the p waves are the yellow circles. it is right about now that the first wave would be arriving right where we're standing. at this point we would feel the shake but we wouldn't know if this was the beginning of a big earthquake or the main shake for a relatively small earthquake. and it is not until the s wave arrival, the red as circled started to arrive in the city that we know it is a big earthquake. it is not until the rupture itself, this