>> earthquake, earthquake. >> reporter: whenever the next big one strikes, tom heaton wants to give people a head start. he's pushing for more funding to expand an early warning system that would alert people in los angeles county to a coming earthquake. before they felt it. >> earthquake, earthquake. >> that's the good news. bad news, earthquakes happen very quickly so we're only talking about seconds to tens of seconds here. >> i keep shoes by my bed now. i don't want to have to walk over glass like i did and take chances. >> as susan aslin tells it, there was no time to lose. with their home crumbling around them her family somehow found a path to safety. >> reporter: what is it like to come back to this home? >> it brings back a lot of memories. >> reporter: they have since moved to a new neighborhood that aslin says is less vulnerable to earthquakes. although she has more peace of mind she will never forget the lessons of nort northridge. michael okwu, al jazeera, california. >> can anything be done to stop the advance of i.s? then later in the show, the battle for aleppo, an exclusiv

. >> there is nothing in nature like a seismic ept, and no one knows that more than dr tom heaton.s been studying quakes since the 1970s, and america's seismic center, caltech. >> one of the things people don't like about earthquakes is when it starts, you have no idea how big the shaking will get. if you are in the wrong place, it can be terrifying. if you know it's in a place that is hazardous, you don't know what is going to happen. >> reporter: what if you could slow down the inevitable, een just for a -- even just for a few seconds - long enough to get out a warning. [ siren ] >> reporter: what's going on? this is the simulation of a 7.2 on the san andrayous and the system is tracking where the earthquake is. showing up on my screen or your screen. >> yaik, yaik, strong shaking. >> telling you that the p wave is headed for us. >> reporter: so this red circle is what we have to worry about. >> it's the weight that has the heavy shaking, heading to us. the closer it gets. >> reporter: it senses the shake's p or primary waves, the yellow circle. they tell scientists that a quake