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Tsunami Warning for Northern California

tsunami.gov

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Re: Tsunami Warning for Northern California

#131

Post by Ancapistani »

eek2121 wrote: post #82
quietthrow wrote: post #33

Interesting observation: I am in a circumstance where I am transitioning from an Android phone (Samsung Galaxy) to a iPhone. I observed that android phone alerted me about an earthquake and that I should be ready to feel tremors. To my surprise as I was pondering how this system works - especially wrt to latency - where it alerts me head of time, I then fell small tremors in 2 or 3 seconds after the alert. The tremor…

I use carrot weather with the critical alerts feature on the iPhone. It works great.

Sigh.

I've lost 15 minutes already because of your comment, and am on track to lose CARROT only knows how much more.

Not only did you prompt me to download CARROT weather, I was foolish enough to set it on the "overkill" personality setting. I was amused by the banter until I found the "achievements" section. Then I saw that there was an achievement for downloading the Vision Pro app, so of course I had to get that one.

I thought it was going to be difficult resisting enslaving myself to the will of CARROT on my iPad... woo boy. I wasn't prepared for the Neal Stephenson-flavored counterfeit GLaDOS that awaited me in visionOS.

Re: Tsunami Warning for Northern California

#132

Post by numpad0 »

mgsouth wrote: post #110
numpad0 wrote: post #74

Earlier quoted context omitted.

LTE ETWS/PWS is mandatory feature, iPhones has the same thing. Maybe you've explicitly disabled it, considering (IIUC) US used it for AMBER alerts and had annoyed lots of people at some point. Generally an earthquake warnings are issued by someone always automatically correlating sensors everywhere, USGS and/or NOAA in case with US, and then cellular carriers broadcasting the alert through LTE feature. This does not…

For folks jumping on saying "that's not a carrier thing". All comms are a carrier thing. Whether it's ETWS, SMS, or IP, it's going through the carrier, they process it, and they do extensive traffic management. Carriers absolutely can and will inspect, proxy, aggregate, and do anything else that will tease out another few % of "free" capacity. [Edit:] All too real scenario: Carrier knows about particular IP addresses…

PWS is tower based broadcast. Everyone within range of a tower gets the alert. Data source is supposed to be local government weather authority, I think USGS and NOAA in US. Or the Meteorological Agency in Japan.

You can do a location-based two way warning system and there are such services, but it's going to be laggy and won't scale to 100M+ simultaneous subscribers. One-way broadcast scales to the planet if wanted.

Re: Tsunami Warning for Northern California

#133

Post by cossatot »

rz2k wrote: post #106
cossatot wrote: post #68

Based on the location and focal mechanism of the earthquake ( https://earthquake.usgs.gov/earthquakes/eventpage/nc75095651... ), this is a strike-slip earthquake on the plate boundary between the Pacific and Gorda/Juan de Fuca plates. Strike-slip earthquakes occur when two plates slide beside each other during an earthquake, usually along a steeply-dipping if not vertical fault. These kinds of earthquakes almost neve…

Doesn't any earthquake, regardless of fault type increase the immediate risk of a submarine landslide? There are many steep canyons on the Pacific coast, and here is just one example of mass casualties from a tsunami resulting from a submarine landslide triggered by a strike-slip fault earthquake: Caltech, 2018[1]: "Contrary to Previous Belief, Strike-Slip Faults Can Generate Large Tsunamis" [1] https://www.caltech.e…

Yes, the probability of tsunamogenic landslides do increase during earthquakes, but it's still quite unlikely for an event of this magnitude tens of km from the continental slope; this is why a properly-calibrated tiered system would be better.

The reason that the Palu event is so notable is precisely because it's uncommon. It's also a very different system: the causative fault is running along the axis of a shallow bay that is only a few km across, so even if the landslide did occur, rapid movement of the steep, shallow coastlines would surely have generated a smaller tsunami. It's a geographical and tectonic situation in which at least a minor tsunami is expected a priori conditional upon an earthquake, so a warning system would account for that in principle. (In practice there isn't time enough to mobilize because the tsunami hits while the ground is still shaking). The bay at Palu is like a somewhat larger Tomales bay--an earthquake right there is going to make some waves. Very different situation than one far off shore.

Re: Tsunami Warning for Northern California

#134

Post by cossatot »

throw83838 wrote: post #117
0xffff2 wrote: post #87

Earlier quoted context omitted.

Looking at https://tsunami.gov/ , it seems like they do have a 4 tier system, but they jumped straight to the highest tier in this case?

HN has good SnR generally, but I would default to trusting their automated system more than Random Internet Guy. Even if the warning gets canceled after measurements become available.

I'm a Random Internet Guy who is a professional in the field (earthquake hazards, not tsunamis in particular).

Re: Tsunami Warning for Northern California

#135

Post by toast0 »

mosdl wrote: post #99
tj-teej wrote: post #96

I am riding the Caltrain south, we slowed to a snail's pace and they said it would take 2hr+ to get to Palo Alto (from SF). A bunch of people got off, and then the conductor comes back on the PA system to say the speed limitation had been limited and "we'll be going back to 79 MPH, hold on to your hats"

First earthquake for the new electric trains probably, I can see why they would be cautious.

A 7.0 earthquake nearby is a pretty good reason to slow down trains, regardless of propulsion.

The easily found page about Caltrain's response to earthquakes [1] doesn't include magnitude 7, but also doesn't include earthquakes more than 100 miles from the tracks either. So I think a brief reduction in speed is reasonable for a large quake within the larger area and quickly ending the restriction as its confirmed the quake was outside the policy scope.

[1] https://www.caltrain.com/rider-information/safety-security/e...

Re: Tsunami Warning for Northern California

#136

Post by LeoPanthera »

cossatot wrote: post #68

Based on the location and focal mechanism of the earthquake ( https://earthquake.usgs.gov/earthquakes/eventpage/nc75095651... ), this is a strike-slip earthquake on the plate boundary between the Pacific and Gorda/Juan de Fuca plates. Strike-slip earthquakes occur when two plates slide beside each other during an earthquake, usually along a steeply-dipping if not vertical fault. These kinds of earthquakes almost neve…

> The USGS's automated systems calculate the location and focal mechanism/moment tensor pretty much instantly from the seismic network.

According to a USGS guy on the news just now, this isn't true. They know the location, and the magnitude, but the moment tensor takes time. Therefore any ocean earthquake 7.0 or above triggers an immediate tsunami warning.

Re: Tsunami Warning for Northern California

#137

Post by gamblor956 »

mort96 wrote: post #59
quietthrow wrote: post #33

Interesting observation: I am in a circumstance where I am transitioning from an Android phone (Samsung Galaxy) to a iPhone. I observed that android phone alerted me about an earthquake and that I should be ready to feel tremors. To my surprise as I was pondering how this system works - especially wrt to latency - where it alerts me head of time, I then fell small tremors in 2 or 3 seconds after the alert. The tremor…

It doesn't sound like the iPhone was behind, but rather warning about something else? It's interesting that Android didn't warn about the tsunami at all, even though that sounds more important than the barely noticable tremors you describe.

Why would the Android give a notification for a tsunami that never happened?

Androids also give tsunami warnings, when appropriate. There was 1 issued just a few weeks ago after an off-shore earthquake in SoCal.

Re: Tsunami Warning for Northern California

#138

Post by dekhn »

colesantiago wrote: post #130
dekhn wrote: post #122

Earlier quoted context omitted.

Why do you believe that AGI would affect earthquake predictions?

> earthquake predictions because we can't currently predict earthquakes? and if we can with AGI we would be saving lives?

Let's unpack what you're saying.

You seem to believe that AGI would be able to predict something that we have been actively researching for decades. I do not see how AGI would suddenly be able to solve a problem that smart people have already been working on, unless the AGI was also "superintelligent" in ways that contributed. AGI proper is merely artificial intelligence, not necessarily superintelligence.

Second, I question that earthquake prediction would make a big difference in saving lives. In particular, earthquake prediction would come with a wide range of risks. It would have to balance true positives with false positives- after a few "OMG everybody leave SF" that didn't pan out, people would just tune out the tsunami warning. Also, telling everybody to leave a large urban area is prone to massive other problems such as increased accidents, disruption of delivery of food and emergency services, and increased overall stress. Likely, more people would die in response (increased road accidents) to your intervention, than were saved.

It seems far more likely that investing effort into identifying actual risks (such as infrastructure that is likely to fail, or individuals living in places that are highly prone to flooding), and addressing those issues through systemic improvements would be a much more useful way to use the machine learning technology we have. And even that isn't necessary; we know what the problems are, we just don't invest in improving it.

Re: Tsunami Warning for Northern California

#139

Post by BurningFrog »

wbl wrote: post #93
teaearlgraycold wrote: post #89

Earlier quoted context omitted.

The system is training me to ignore it already. I’m in SF and we had a flash flood emergency alert. I never heard of or saw any floods. I could believe a street or two might have had a few inches of water at most. But honestly I’d bet against even that. And then there’s this tsunami alert today.

SF topography means some places like the Mission and Dogpatch can have severe floods and the rest be fine.

[flagged]

Re: Tsunami Warning for Northern California

#140

Post by jerlam »

0xffff2 wrote: post #87
cossatot wrote: post #68

Based on the location and focal mechanism of the earthquake ( https://earthquake.usgs.gov/earthquakes/eventpage/nc75095651... ), this is a strike-slip earthquake on the plate boundary between the Pacific and Gorda/Juan de Fuca plates. Strike-slip earthquakes occur when two plates slide beside each other during an earthquake, usually along a steeply-dipping if not vertical fault. These kinds of earthquakes almost neve…

Looking at https://tsunami.gov/ , it seems like they do have a 4 tier system, but they jumped straight to the highest tier in this case?

It's a three-tier system, I was confused when I was looking at it. The fourth item is "threat" which you would think is higher than "warning", but "threat" is only used outside of the US.
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