Tsunami watch has been cancelled for Washington, Oregon, and California.

https://twitter.com/NWSEureka/status/955777068377296896

We like to laugh about the Tuesday siren tests, but times like this are why we do them. If a tsunami really does hit WA and OR expect the waterfront sirens to make a pre-dawn announcement.

I'm a recent newcomer to the Bay area. What is the Tsunami situation for places like Mountain View? Places like the GooglePlex are pretty close to the Bay. Is there even any real high ground in the area?? If something happens for real, do sirens sound?

Excluding the coast and the east bay, it is not really a concern. A tsunami would have to come through the golden gate channel and make a quick turn to get to Mountain View with any strength.

The inundation map for Mountain view is here: http://www.conservation.ca.gov/cgs/geologic_hazards/Tsunami/...

And here is one for the entire bay area: http://www.conservation.ca.gov/cgs/geologic_hazards/Tsunami/...

The remainder of the inundation maps can be found here: http://www.conservation.ca.gov/cgs/geologic_hazards/Tsunami/....

Here is an animated simulation of a tsunami hitting the bay area: https://www.youtube.com/watch?v=bP_AIWgknfI

Most bay area residents do not fear tsunami. The risk is low since local faults slip side to side which do not cause tsunami. A subduction fault can cause a tsunami, such as in Alaska, Japan or Chile. We would get hours of warning in such a case.

Is Twitter really the official way to notify people of danger? Or is there also a cell phone warning system?

There are multiple notification systems available, I find that the twitter account tends to have a lot more info about hyperlocal and situational events vs the text-based system. I've just never straight up heard the outdoor one go off except for tests.

Folks in SF that want to sign up for the texts can do so here: http://sfdem.org/public-alerts

The national and state emergency alert systems have a cellphone program. You should get cellphone alerts in an emergency (I get them for flooding, AMBER alerts, etc.).

How would they know cell phone numbers? Where I live they call landlines for emergency alerts but there's no other way to specifically target residents.

If it was a big deal, beyond the opt-in SF text alerts, there's a thing called Wireless Emergency Alerts. It's geographically targeted. It's basically like Amber Alerts going to your phone except for imminent emergencies.

There has been some controversy about the timing and use of WEAs for evacuations for the big wildfires in California recently, but I imagine it's hard to balance alarm fatigue with the need to warn people.

The state can broadcast emergency messages, it doesn't need to send them individually to some database of cell phone numbers.

Alert About Missile Bound for Hawaii Was Sent in Error, Officials Say https://news.ycombinator.com/item?id=16140761

How do amber alerts work? When I lived in SF I got SF-related alerts. I don't know enough about how they work - but it sounds like tech that could be re-used for major emergency alerts.

As I should have realized, they're sent to all wireless phones in the area. On an iPhone at least both Amber and Emergency alerts are on by default but you can turn either of them off.