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Tsunami warning ends for B.C. after large earthquake strikes off Alaska

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Re: Tsunami warning ends for B.C. after large earthquake strikes off Alaska

#21

Post by tempestn »

JorgeGT wrote: post #17
porker wrote: post #16

Earlier quoted context omitted.

Do you know why these reports mention Hawaii, rather than (say) Vancouver and other coastal cities nearer to the epicenter, where I would imagine a tsunami would reach first?

The page is specific to Hawaii, but you can go to http://www.weather.gov/ and in the map, click your region and then "tsunami warning" or "tsunami watch" to see estimated times for other states. This is the tsunami watch notice for coastal areas of Oregon, Washington & California: http://forecast.weather.gov/wwamap/wwatxtget.php?cwa=sew&wwa...

You can also quickly access this info at http://www.tsunami.gov. Or at least normally it's quick; page is taking a good 10 seconds to load for me right now—under a bit of load, presumably.

It includes Canada as well. (In fact, the BC Emergency site quotes from it and links back to it!)

Re: Tsunami warning ends for B.C. after large earthquake strikes off Alaska

#22

Post by adanto6840 »

onnoonno wrote: post #19
JorgeGT wrote: post #8

Earlier quoted context omitted.

Link to the actual buoy data page: http://www.ndbc.noaa.gov/station_page.php?station=46410&type... Worth noting that other nearby buoys don't show such a dramatic wave: http://www.ndbc.noaa.gov/station_page.php?station=46409&type... Here's a map: http://www.ndbc.noaa.gov/obs.shtml (click on the blinking ones) And here's a map of tsunami-capable tide stations: https://tidesandcurrents.noaa.gov/tsunami/#

What I don't get is that nearly all the buoys that have that moving icon "Tsunami alert" show some excitation at the ~9:45GMT mark. But I would of course expect the buoys that are farther away to only show some kind of peak when the wave actually reaches them. And it looks like they are thousands of km away, so some of them should not even have been reached yet. Some what is going on there? Is the data time actually…

I'm probably completely wrong, but am wondering and trying to deduce the same thing. My assumption, guess really, is that they were remotely activated into "Tsunami Mode" -- a more rapid-pulse reporting mode or similar, which just is a bit noisier perhaps?

Total layman's guess though -- would love to know more if anyone knows the answer.

Re: Tsunami warning ends for B.C. after large earthquake strikes off Alaska

#23

Post by JorgeGT »

onnoonno wrote: post #19
JorgeGT wrote: post #8

Earlier quoted context omitted.

Link to the actual buoy data page: http://www.ndbc.noaa.gov/station_page.php?station=46410&type... Worth noting that other nearby buoys don't show such a dramatic wave: http://www.ndbc.noaa.gov/station_page.php?station=46409&type... Here's a map: http://www.ndbc.noaa.gov/obs.shtml (click on the blinking ones) And here's a map of tsunami-capable tide stations: https://tidesandcurrents.noaa.gov/tsunami/#

What I don't get is that nearly all the buoys that have that moving icon "Tsunami alert" show some excitation at the ~9:45GMT mark. But I would of course expect the buoys that are farther away to only show some kind of peak when the wave actually reaches them. And it looks like they are thousands of km away, so some of them should not even have been reached yet. Some what is going on there? Is the data time actually…

Not an oceanic scientist but sound speed in water is ~1500m/s. This is the speed at which a pressure perturbation propagates. The speed at which the actual tsunami wave would propagate is much more slower than this. So I believe that the excitation marked in the plot is the pressure wave caused by the earthquake, which travels orders of magnitude faster than an actual water wave caused by the earth displacement.

Re: Tsunami warning ends for B.C. after large earthquake strikes off Alaska

#24

Post by onnoonno »

adanto6840 wrote: post #22
onnoonno wrote: post #19

Earlier quoted context omitted.

What I don't get is that nearly all the buoys that have that moving icon "Tsunami alert" show some excitation at the ~9:45GMT mark. But I would of course expect the buoys that are farther away to only show some kind of peak when the wave actually reaches them. And it looks like they are thousands of km away, so some of them should not even have been reached yet. Some what is going on there? Is the data time actually…

I'm probably completely wrong, but am wondering and trying to deduce the same thing. My assumption, guess really, is that they were remotely activated into "Tsunami Mode" -- a more rapid-pulse reporting mode or similar, which just is a bit noisier perhaps? Total layman's guess though -- would love to know more if anyone knows the answer.

> My assumption, guess really, is that they were remotely activated into "Tsunami Mode" -- a more rapid-pulse reporting mode or similar, which just is a bit noisier perhaps?

That sounds like a very good guess. But then, the spikes that are purported to be the Tsunami in the media is just the ADC having a couple bad samples from being switched into a different mode or so :-)

If any USGS person is reading this thread here: Take it as a issue report that your page should be readable and understandable by lay persons, at least lay persons with a non-geophysics STEM background :D

Re: Tsunami warning ends for B.C. after large earthquake strikes off Alaska

#25

Post by JorgeGT »

tempestn wrote: post #21
JorgeGT wrote: post #17

Earlier quoted context omitted.

The page is specific to Hawaii, but you can go to http://www.weather.gov/ and in the map, click your region and then "tsunami warning" or "tsunami watch" to see estimated times for other states. This is the tsunami watch notice for coastal areas of Oregon, Washington & California: http://forecast.weather.gov/wwamap/wwatxtget.php?cwa=sew&wwa...

You can also quickly access this info at http://www.tsunami.gov . Or at least normally it's quick; page is taking a good 10 seconds to load for me right now—under a bit of load, presumably. It includes Canada as well. (In fact, the BC Emergency site quotes from it and links back to it!)

I know but since tsunami.gov it's getting is getting hammered I figured out it's better to leave their bandwidth for people in risk rather than hit them with the HN frontpage effect.

Re: Tsunami warning ends for B.C. after large earthquake strikes off Alaska

#26

Post by willvarfar »

JorgeGT wrote: post #8
dawnerd wrote: post #7

Some buoy data: https://twitter.com/BillKarins/status/955747863140675585

Link to the actual buoy data page: http://www.ndbc.noaa.gov/station_page.php?station=46410&type... Worth noting that other nearby buoys don't show such a dramatic wave: http://www.ndbc.noaa.gov/station_page.php?station=46409&type... Here's a map: http://www.ndbc.noaa.gov/obs.shtml (click on the blinking ones) And here's a map of tsunami-capable tide stations: https://tidesandcurrents.noaa.gov/tsunami/#

At the top of those pages I see this message:

> Due to the Federal Government shutdown, NOAA.gov and most associated websites are unavailable. This site will remain accessible during the federal government shutdown; however, information on the site may not be up to date and we may not be able to respond to inquiries until appropriations are enacted

so, is it up to date?

Re: Tsunami warning ends for B.C. after large earthquake strikes off Alaska

#27

Post by Jedi72 »

mathgenius wrote: post #12

Wow 15 hours to australia, that thing is moving fast.

Will this wave affect boats? Imagine being on a yacht in the middle of the Pacific (not Atlantic Doh!) when a 10m wave moving at 20m/s hits (figures not accurate just guesses)

Re: Tsunami warning ends for B.C. after large earthquake strikes off Alaska

#28

Post by onnoonno »

JorgeGT wrote: post #23
onnoonno wrote: post #19

Earlier quoted context omitted.

What I don't get is that nearly all the buoys that have that moving icon "Tsunami alert" show some excitation at the ~9:45GMT mark. But I would of course expect the buoys that are farther away to only show some kind of peak when the wave actually reaches them. And it looks like they are thousands of km away, so some of them should not even have been reached yet. Some what is going on there? Is the data time actually…

Not an oceanic scientist but sound speed in water is ~1500m/s. This is the speed at which a pressure perturbation propagates. The speed at which the actual tsunami wave would propagate is much more slower than this. So I believe that the excitation marked in the plot is the pressure wave caused by the earthquake, which travels orders of magnitude faster than an actual water wave caused by the earth displacement.

But that doesn't fit the data, either. The buoys all report something around the 9:45ish GMT mark. And 1500m/s would mean you reach Mendocino bay in California only about now or so. But have a look at the plot:

https://archive.fo/KsN8b

Re: Tsunami warning ends for B.C. after large earthquake strikes off Alaska

#29

Post by [deleted] »

adanto6840 wrote: post #22
onnoonno wrote: post #19

Earlier quoted context omitted.

What I don't get is that nearly all the buoys that have that moving icon "Tsunami alert" show some excitation at the ~9:45GMT mark. But I would of course expect the buoys that are farther away to only show some kind of peak when the wave actually reaches them. And it looks like they are thousands of km away, so some of them should not even have been reached yet. Some what is going on there? Is the data time actually…

I'm probably completely wrong, but am wondering and trying to deduce the same thing. My assumption, guess really, is that they were remotely activated into "Tsunami Mode" -- a more rapid-pulse reporting mode or similar, which just is a bit noisier perhaps? Total layman's guess though -- would love to know more if anyone knows the answer.

[deleted]
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