[NoImmatureAdHom]

This is also an interesting point! I assume there's a network of monitoring stations all over the world which are hooked up to the internet & other modes of speed-of-light communication.

https://www.ldeo.columbia.edu/~richards/my_papers/Richards&K...

https://www.ctbto.org/verification-regime/monitoring-technol...

I can't figure out how to get their data in real time and set up push alerts, though...!