These are all obvious answers. Still begs the question of what's the value of having these discussions here. There are plenty of discussions that are not permitted on HN (even if they would garner useful discussion). I only posit that this type of news also lends no value to this forum (SV locals don't or shouldn't depend on HN for local emergency news), and so should be removed/banned. Just my 2¢ - downvote away.
the value is connection. you're free to disregard that, but as humans, and not automatons, we sell to connect to out fellow humans in more ways than work. now, you can point out that it's a very SV-centric post, and it is, but there's a ton of other SV news here, so that objection's probably moot. Other regions of the world experience earthquakes and the discussion of the science and technology behind the early warning system that was deployed is interesting beyond the bay area.
I find it helps to remember that I don't have to click on every link on this site. If something doesn't look particularly appealing to me, I remind myself that there are other folks who read the site too, and while I don't understand why some of the things here are interesting to folks it's still OK that they are here - I am not the sole member of the "target audience". I just skip that link and read something more appealing.
There is fascinating science and technology associated with earthquakes, as well as interesting stories and history (though fewer of those in this thread)
The key part of my comment was "things like this". While this earthquake wasn't anything to write home about, a think like this, an earthquake, could easily be much worse, and therefore deeply impact folks that live here. It hasn't been that long since Loma, and that could be said to have deeply impacted those that lived there then, and still impacts us that do today, no?
HN works on a voting system, so that people can register what they feel is important, and if enough people do that then things show up on the front page.
it's interesting to compare and contrast your experience with someone else's. And since this is an experience everyone around here has had, we have it all in common, unlike say if there's a robbery on 1st street which might affect less than .0000001% of users on this site.