Earthquake early warning systems are a top 10 peak human achievement in my book. No joke, I tear up watching videos of Japan's EEW system alerting people of possible danger just in time.

There are streamers who's whole thing is watching these alerts and setting up bobbleheads and glasses of water and stuff to show the shaking. It's so so so cool. Look at what we can do for each other you guys :')

https://www.youtube.com/watch?v=imH-ZyXwX5Q

It sounds impressive but it's worth considering that this was a large quake that was felt by basically half of the country. You do not get this much warning if you are anywhere near where damage happens.

The 45 seconds is better thought of as the time it takes for the quake to propagate to Tokyo

Yeah. That's leagues better than what I get in Taiwan. The alert often arrives when the building is shaking or even after. I've never had a meaningful headstart.