Tsunami Alert Issued for Japan | Hacker News Reader

Tsunami Alert Issued for Japan

tsunami.gov

89 pointsLinuxBender50 comments

The real story here is that there is on going investigation by JMA scientists that this might be a precursor to a larger "mega thrust quake", the government has asked people in certain areas to evacuate for the next week or so, and for everyone else, make emergency preparations.

https://www3.nhk.or.jp/nhkworld/en/news/backstories/3509/

Edit: It's considered cautionary, just so no one freaks right out.

That page doesn’t describe anything about evacuations? At least, the ones mentioned are in relation to the tsunami warning.

I find the information surrounding this mega quake can generally be summed up as ‘be careful’. Which is kinda silly. If the earthquake happens there’s nothing special you can do that you wouldn’t otherwise.

It might prompt people to ensure their disaster kit is in good order, know where the shelters are, home preparation, listen to radio for alerts, etc, etc.

https://www.bousai.metro.tokyo.lg.jp/book/pdf/en/01_Simulati...

You are correct that for some people it will be situation normal, but not everyone is always prepared.

Yes, it's in English, it's light on details, if you can read Japanese, here:

https://www3.nhk.or.jp/news/special/saigai/uploads/advanceev...

https://www3.nhk.or.jp/news/html/20240808/k10014542271000.ht...

It's absolutely wrong to say that it's "silly" to have warning?

https://www.japantimes.co.jp/news/2024/08/08/japan/nankai-ea...

The weather agency issued the lower level alert on Thursday, urging people to be prepared for cases requiring evacuation. No evacuations are required for the alert level.

A warning means people would need to be on higher alert, and officials would urge those who wouldn’t be able to evacuate quickly to do so before any large quake occurs.

There are couple "near-end of this country" hypothetical geological disasters suggested for Japanese mainland, and Nankai Trough Earthquake is one of them.

I suppose the risk is technically elevated, but it's not a newly discovered risk or theorization at all - this concept predates modern plate tectonics theory.

There have been several of these quakes in the past, why would it “end Japan” ?

Not saying it will “end Japan”, but the government estimates that this quake could kill around 320,000 people (mostly by the tsunami).

The statistics are a testament to how good the engineers, planners and builders are in Japan. I think we saw the same thing but from the 1920s onwards the deaths from building collapse during a mega quake are down to like 3% of overall deaths whereas the absolute vast majority of deaths are now drownings from Tsunami.

In California I’ve seen almost zero preparedness compared to what I’ve seen in Japan and honestly, the San Andreas fault looks nasty.

I was recently in Japan when an earthquake alarm went off.

Turns out they have a ton of earthquakes - most days look to have 3-4, and as of this posting there have been seven today.

https://www.data.jma.go.jp/multi/quake/index.html?lang=en

A statistic I’ve seen—but am unable to verify at the moment—is that about 20% of the human-perceptible earthquakes that occur on Earth each year take place in Japan.

I’ve been living in the Tokyo area for many years. Yes, it’s not unusual to have three or four earthquakes a day nationwide, but most are small and felt in only a limited area. I typically notice one every month or two on average. More occur, but it’s easy to miss the smaller ones if you are outside, on a train, etc.

An exception was after the huge Tohoku quake on March 11, 2011. For months thereafter, I felt aftershocks every day. Here’s the nationwide list for a couple of weeks later:

https://typhoon.yahoo.co.jp/weather/jp/earthquake/list/?sort...

There were over a hundred quakes just on March 27, all strong enough to be felt.

We may have seemed to get a bit blasé about earthquakes then, but I don’t think people here ever really get used to them. When the shaking begins, you never know whether it will end quickly or, in a few seconds, get much stronger and possibly destructive.

Many people find the alarm worse than the quake, how did you find it ? :)

I live in Taiwan and find the earthquake alarm scarier than the majority of earthquakes that follow. The alarm in Japan sounds mellow by comparison.

This, I gotta see

It felt like the alarm was announcing the end times, but we couldn't feel the quake at all. It was a 5.x but far away

I heard a funny story where someone was working in Tokyo in a dev shop, and they had something like 100 hand sets for doing QA on different smart phones. Apparently they all went off at the same time. That would've been wild.

The interesting thing is that M7 (this) quakes occur roughly 10,000 less frequently than M3 quakes.

Isn't it log scale? So M7 is also aprox. 10 000 times stronger? Still linear correlation between strength and occurrence is interesting.

Yes that is what 10000 times more often than M3 means because 10000 is 10 to the power (7-3)

(0906 UTC)

The warning has since been lifted.

Please provide a source

That same site. You can see when a change in the alert was issued here:

https://tsunami.gov/?p=PHEB/2024/08/08/24221000/3/WEPA40

Phew! I love Japan and hate for another natural disaster to occur there!

I wonder if a tsunami mixes the fish around in the water or if they can avoid to get dragged along.

IIRC the water displacement on open seas is super modest, only when the thing hits shallower water near the coast does it become a problem

Edit: https://m.youtube.com/watch?v=-VcWF8dIDj4

They're a few miles off the coast, ~10 m high waves, 38 m deep water according to some comment that translates the audio. pretty scary vid, for sure.

Hard to imagine what it must've felt like going over the crest of that wave and just wondering what's next. Anyone who has surfed decent sized waves know this feeling.

Judging by the translated conversation, they seem pretty intense about quickly detecting, and properly turning into, the next wave...

Strongly depends on if it's a deep water portion or if it's shallow.

In deep water, a tsunami is boring and nearly unnoticable. There's some motion, but it's essentially all low displacement coherent movement and very little other motion. When that mass of water gets to shallow water, it's essentially the opposite, there's effectively big mass of water that's pushed on land, and that's very turbulent.

Like cracking a whip.

Yes, and do tsunamis ruin the seaweed farms?

Got a link to the earthquake alarm sound? I'd love to hear it.

Here in southern USA we have a monthly tornado siren test. Sounds like the aliens are landing

nothing to see here. this was a 5 on the scale and you should not expect any major earth shattering waves.

there are earthquakes everyday here.

In fact there was a M7.1: https://earthquake.usgs.gov/earthquakes/eventpage/us6000nith...

Japan use Shindo scale that represents human perceptions and property damages better than the total energy measure represented by the magnitude scale. This one was up to Shindo 6 minor at some municipalities and Magnitude 7.1 total.

Shindo 5 major is around where it gets scary but many concrete buildings survive, at 6-7 you might not want to delay packing for an evacuation.

That’s interesting, thank you. Reminds the Taiwan subjective scale too. Know what that’s called?

Would not be surprised if that was influenced by Japanese, given their colonial history.

Looks like this[1] is it, called "Central Weather Administration seismic intensity scale". There are few more similar standards around the world[2]. Looks like Taiwanese version is indeed related to Japanese standard. From [3]:

> 臺灣的地震觀測始於日治時期，2000年8月之前的震度分級是沿用日本1936至1948年所使用的震度分級，

My crudest roughly-letter-to-letter translation:

> Taiwan's earthquake observation started during Japanese ruling period, Aug 2000 and before's intensity classification thereby following Japanese 1936 to 1948 -at employed intensity classification,

1: https://en.wikipedia.org/wiki/Central_Weather_Administration...

2: https://en.wikipedia.org/wiki/Seismic_intensity_scales

3: https://zh.wikipedia.org/wiki/%E4%BA%A4%E9%80%9A%E9%83%A8%E4...

Excellent! The CWA site is actually really cool. I like how they do the alerts, and present the information on rainfall, nearby taiphoons, wind. It's all organized and colored well. Just a good synthesis of lots of information at a glance, very impressive! This kind of thing may be standard for weather sites but I haven't see it done this well elsewhere.

This is unfortunate.

'ZCZC' and 'NNNN' - all caps? Is this still set up for teletypes?! Please tell me there's not somewhere still getting these via baudot?!

ZCZC appears to be a signaling codeword for this protocol:

https://en.wikipedia.org/wiki/NAVTEX

- "NAVTEX messages are transmitted using binary frequency-shift keying (BFSK) at 100 bit/s and a 170 Hz frequency shift"

It's a low-bandwidth way to send weather tweets to seafaring boats.

ZCZC is the Start of Message signal for a few protocols, including NOAA's SAME, which seems relevant here as this is a NOAA broadcast. https://en.wikipedia.org/wiki/Specific_Area_Message_Encoding

I love your phrase 'weather tweets'

Why not? Japan was using floppy disks until last week or so :D

Also, it's not like someone is going to be requesting to add emojis to these reports.

It's clean, human-readable, it looks like it should not be difficult to parse if the case needed... so why change it?

Because that's how the younger employees feel like they can contribute by rewriting everything. Clearly, anything created by theOlds can be improved upon using modern but of course they'll make it emoji friendly because that's how you know it's modern.

Floppy disks? Nah that was ages ago. We've upgraded to fax machines.

Wait till you see how messages are transmitted at DND…

Or weather reports for aviation[1]…

[1] https://en.wikipedia.org/wiki/METAR

Dungeons and Dragons?

Department of national defence maybe

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