Japan Issues Tsunami Warning After Magnitude 7.6 Earthquake

A powerful magnitude 7.6 earthquake has shaken Japan, prompting tsunami warnings and orders for residents to evacuate. From a report: A tsunami as high as 3 metres (10ft) could hit the country's north-eastern coast after the earthquake occurred offshore at 11.15pm local time (2.15pm GMT), the Japan Meteorological Agency (JMA) said. Tsunami warnings were issued for the prefectures of Hokkaido, Aomori and Iwate, and tsunamis from 20-50cm (7-18in) high were observed at several ports, JMA said.

The epicentre of the quake was 50 miles (80km) off the coast of Aomori prefecture, at a depth of 30 miles, the agency added. On Japan's one-to-seven scale of seismic intensity, the tremor registered as an "upper six" in Aomori prefecture -- a quake strong enough to make it impossible to keep standing or move without crawling. In such tremors, most heavy furniture can collapse and wall tiles and windowpanes are damaged in many buildings.

Fukushima Volume 2?

[shanen]

Thanks for the heads up. Middle of the night here, but if you want to follow it in English, https://www3.nhk.or.jp/nhkworl... [nhk.or.jp] has a live feed. I'm watching it now. Haven't seen the epicenter, but the tsunami warning zone indicates the same area as the quake in 2011 that killed 20 thousand people and led to the Fukushima #1 fiasco.

Re:Fukushima Volume 2?

[skam240]

Fukushima Volume 2? Probably not given that the Fukushima earth quake was a 9.0. These measurements are exponential so there's a pretty sizable difference between 7.6 and 9.0.

7.6 is still enough for some damage though. Hopefully that's all at a minimum for you folks over there. Best wishes.

Re:

[shanen]

ACK, and I was also probably wrong about the location. I had just had my first look at a tiny map and I didn't realize how much farther north the tsunami zone was. Only about a three-meter tsunami, which is quite small compared to March 11th.

Re:

[skam240]

You're right there by where the earthquake happened though. Of course your mind is jumping straight to concerns like this. Makes perfect sense to me.

Re:

[jhoegl]

I think the unknown is the problem.

What causes tsunamis from earthquakes, as far as I understand, is the displacement of water as a result of shifting rocks in the water. That could mean a gap opening, closing, or a huge amount of rocks moving from the top of a ravine to the bottom.

So, it isnt the size of the quake that is the concern, it is the unknown shifting of material underwater. And 30 miles deep is pretty tough to gauge significant changes quickly.

Re:

[tragedy]

So, it isnt the size of the quake that is the concern, it is the unknown shifting of material underwater. And 30 miles deep is pretty tough to gauge significant changes quickly.

Not that it invalidates what you are saying, I just want to be clear the 30 miles deep is underground. No water to displace there. The deepest part of the ocean is about 7 miles deep.

Re:

[jhoegl]

I did think it weird, and I should have validated, LOL.

Thanks

UPDATE: This may be a FORE-shock!

[storkus]

https://www3.nhk.or.jp/nhkworl... [nhk.or.jp]
"Updated: Japan issues mega-quake alert after M7.5 tremor" and
For those of you outside the USA, the hypocenter is 54km deep, about moderate as these kind of quakes go.
And TEPCo says everything at Fukushima Daiichi is normal, but we know how much we can trust what they say.

Re:

[bn-7bc]

yw because TEPCO has proven to be 100% reliable with it's information flow previously. I think the IAEA needs to dispatch a team to check out the situation for themselves. And if they are denied access, well we'll all know TEPCO is trying to hide sorting at that point.

Re:

[bn-7bc]

Meanwhile-ish at Chernobyl [businessinsider.com]

Re:

[RockDoctor]

This one magnitude 7.6 ; 2011 was a 9.2, 9.1 thereabouts (I can't be bothered looking it up).

That's 2.5 or so orders of magnitude lower which, for earthquakes is a 10^(1.5*diff.magnitude) factor of difference in energy release. Which, for those who can't do mental maths (see "dollar store" rant) is 10^-(3.6 to 3.7) or between 4 and 6 THOUSAND times less energy release.

You didn't need to wake up fully. I saw the alert on my phone, did the maths, and went back to sleep.

18 Inch Tsunami?

[SlashbotAgent]

An 18 inch Tsunami?

I guess it could get my shoes wet, or flood a road way.

Re:18 Inch Tsunami?

[FudRucker]

18 inches of fast moving water is enough to knock you off your feet and carry you away, you would be grabbing whatever you could to get out of that

Re:

[jonadab]

I mean, it depends on exactly how fast the water is moving (as well as how deep it is; both things matter). If we're talking normal river current (say, 1 foot per second), most adults can stand in eighteen inches and be fine, if it doesn't catch them off guard. If the current is faster, then it doesn't have to be as deep to have essentially the same effect, or if it's deeper, it doesn't have to be as fast.

There are of course some caveats to the above. One is, once you get past about 4-5 feet deep (depend

Re:

[thegarbz]

You misspelled "flood a road away" The height of moving water is quite insignificant to the speed at which it moves. An 18" tsunami may get your feet wet, or may take you and your car across the suburb destroying quite a lot in its path.

The question is one of momentum. Very shallow water can be insanely destructive depending on how it moves. Just a few inches of expected moving water is required to have engineering considerations for foundations to prevent them being undermined.

No big deal

[furrygeek]

Here in Tokyo (Narita), it was just a little shake that lasted for about 20 seconds or so. It was so mild, I had to ask my partner "Did you feel that?" I imagine it was more severe in Hokkaido, but I haven't heard reports of any significant damage. The predicted three metre-high tsunami was only about 50cm.

Re: No big deal

[dotslashdot]

That is what she said. Lol.

Re:

[hcs_$reboot]

I had to ask my partner "Did you feel that?"

What did he answer?

Epicentre vs Hypocentre

[test321]

The epicentre of the quake was 50 miles (80km) off the coast of Aomori prefecture

Yes this the epicentre.

, at a depth of 30 miles

No then you're talking about the hypocentre.

Re:

[Anonymous Coward]

you so smart

Re:

[test321]

Thanks, I'll tell my mom. I'm not actually that smart, but she'll love to hear that anyway.

USGS page on this earthquake

[david.emery]

https://earthquake.usgs.gov/ea... [usgs.gov] The USGS earthquake.usgs.gov site does a great job tracking earthquakes worldwide. There's valuable information for both casual readers and for geologists. (Even though we covered 'beachball' moment tensors in my Structural Geology course, I never really grokked how to interpret the diagrams, and always have to look up samples to see which way the slip is going.)

Re:

[Anonymous Coward]

Until the Republicans find it and shut it down.

Re:

[haruchai]

i'm shocked DOGE didn't end that already

It's all in one's relations.

[Ostracus]

Can climate change cause more earthquakes and volcanic eruptions? [preventionweb.net] Plus S15D-0223 Investigating a possible link between cryoseismic activity and acceleration of anthropogenic climate change [confex.com].