In Canada, we have mandatory Amber Alert notifications that affect all modern cell phones. It is loud so you aren't likely to miss it. These alerts cannot be muted, and require the user to acknowledge receipt or another alert will come shortly thereafter. This helps to catch people during alert time in case their phones are not on, or they're in the shower, or whatever.
I am surprised California and other wobbly places don't use the same system, with the addition of quake and forest fire alerts. Everybody here knows the alert sound instinctively now, so even if you're in public and hear someone else's phone go off, we all know what it is.
We do have the same system, commonly used for Amber Alerts, Silver Alerts, Blue Alerts, fires, floods, COVID-19 lockdown, foreign missile tests, etc. However there's no mandatory ack, and except for "presidential alerts" they can all be turned off. That's what I did after I got woken up for an evacuation notice 20 miles away from me, feel back asleep, and got woken up again by the followup message 30 minutes later saying it was just a drill.
Anyways, the wireless emergency alert system has like 5-30s of latency. I suspect that might be enough to make push notifications a better solution. There's a # of apps taking that approach (full disclosure, my employer makes one of them), I think they all ingest data from a private USGS Kafka server
The WEA alerts use a pretty high threshold for whether or not to message people, and it's only been in place for a few years. It's possible you haven't been in an intense enough location during a 5+ magnitude earthquake. You might be interested in the ShakeAlert after action reports[1] which include maps showing roughly who was notified, how much advance warning someone potentially received, etc.
One downside with WEA is that it doesn't give a ton of granularity, so in theory they only issue them in areas where the alert will potentially save lives (despite latency concerns). One thing that the Android alerts do which I think is smart is to send out lower-priority alerts for non-dangerous earthquakes that still have enough intensity to be felt. Having that lower prio alert helps build confidence and trust in the system. Turns out people actually like advance warnings for smaller earthquakes, and unlike a real "oh shit duck and cover" alert those ones don't bypass Do Not Disturb mode.
I've always lived in Los Angeles and Bay Area until a month ago. But the one "duck and cover" earthquake here in the 21st century was probably before these alerts existed.
As other commenters have mentioned, they do have the same system in the US, but they actually use the proper alert types, unlike in Canada where they're all just thrown under the highest alert level that can't be ignored or silenced.
Japan has had this for years, but California's app for this is still in beta IIRC.
It's funny to me that one of the world's tech capitals has taken so long to get this rolling. To be fair, California doesn't have earthquakes as regularly as Japan (at least not of the same magnitude). I guess this is another symptom of our crumbling institutions in the US, we only get services quickly if there's a profit to be made. In the popular imagination, innovation is only the domain of private companies.
Technical detail, amber alerts refer specifically to missing children. The other ones aren't amber alerts. But seemingly all of them trigger a loud sound.
Actual Amber Alerts are the ones that bother me. If I'm in my office or eating dinner, I don't want to know about a missing child last seen 20 miles away
If it was actually localized, the volume would be okay. But I live in Toronto and sometimes get amber alerts from Hamilton for parental custody disputes. That's definitely not how that system should be conducted.
I am surprised California and other wobbly places don't use the same system, with the addition of quake and forest fire alerts. Everybody here knows the alert sound instinctively now, so even if you're in public and hear someone else's phone go off, we all know what it is.