What's the overall thermal profile of such a device at screen sizes given that it's based on flash heating elements?

Participating Android phones are hooked into two different alert systems. One is ShakeAlert, but that wasn't the one that offered advance warning here. The other is that phones that have opted into the Android Earthquake Alerts System use mass collective data from their accelerometers to form a rudimentary real-time seismology dataset. The scale of the network is used to filter the seismology readings from the everyday movement noise. It's the data from that which was able to trigger the alert so rapidly and beat the shockwave, which is why this is discussing Android phones in particular.

As well as range, it also depends on if your phone is set up to receive alerts from Google's newer Android Earthquake Alerts System. Not all manufacturers will have set up for that out of the box, some may only be hooked into the government alert system, which was apparently slower in this case.

SLS will be launching an unmanned but astronaut-capable Orion capsule to the moon in November, as soon as the hurricane cleanup is done.