[numpad0]

Carrier alerts is the fastest. Not only the whole process from detecting tremors to alerts take 30 seconds or so, there aren't other data sources than what those carriers use anyway, so there's just no way Google can be faster than carriers.

PWS is also a broadcast, meaning the phones don't have to wait for cellular timeslots, so it's faster and bandwidth efficient in that regard too.

[jcrawfordor]

Unfortunately the architecture of IPAWS can introduce fairly long delays. The EEWS system uses a dedicated channel to deliver alerts to WEA more quickly, since a study by USGS/NIST had determined that IPAWS could not meet time objectives (typically ~5 minutes end to end). The tsunami warning center, like basically everyone except for USGS, has to originate alerts through IPAWS. The performance and latency problems with IPAWS have been flagged by GAO a couple of times now but it's not something that receives much investment. All-Hazards Radio (weather radio) should actually be a faster alerting mechanism for tsunamis, in practice, since NOAA operates that system themselves.

The Android Alerts are actually coming off of IPAWS as well, but I believe they take a feed directly from the publishing system and do all of the routing themselves. Their implementation is of course quite a bit faster than IPAWS rather creaky and sort of batch-centric architecture.

[Bratmon]

Android alerts got there way before carrier alerts today.

Reality doesn't care what you think should be the fastest.

[Melatonic]

When I was on Android the integrated Google system was always much faster than anything else