Magnitude 7.3 earthquake off the Coast of Fukushima Prefecture | Hacker News Reader

Magnitude 7.3 earthquake off the Coast of Fukushima Prefecture

data.jma.go.jp

167 pointsKuinox67 comments

It was two earthquakes -- one "small" one and another "big" one that followed about a minute later.

On TV, they were announcing the quake intensity of the first one and and there was a video feed of the Fukushima nuclear plant, as they usually do when there's a strong quake in that area. A moment later, the feed was shaking violently -- I thought it was a replay of what was taken earlier, but it must have been the "big" one.

In Tokyo, we felt the secondary wave of the first overlapping with the primary of the second, so it was disorienting and scary. Although the quake intensity itself wasn't serious in Tokyo.

Well, seems like a Shinkansen derailed. It doesn't seem very serious as there's someone tweeting about it from inside that train...[1] There's also a tweet that the part of the overhead power line broke off and fell[2], so it may take a while to get back in service...

[1]: https://twitter.com/tokimemo1130/status/1504110997732139024

[2]: https://twitter.com/R19i90/status/1504112207746936832

I would be interested to know more about the derailing. The shinkansen network has automated quake protections that stop the trains when a quake is detected, while that's not a foolproof system, I am sure a derailment at full speed would be very different to this picture. Either it worked or the train was at a slower part of it's journey, perhaps even stopped.

Shinkansen moves fast enough it's difficult to fully stop in time unless it gets a decent amount more warning. Probably slowed down enough it was pretty minor though.

It probably slowed down/stopped for the first quake before the 7.3 hit and derailed it?

The big wasn't still very big here in Tokyo, but it felt weird. The shake was in different direction than usually, it's hard to describe. It also lasted quite long in detectable intensities, although the peak shake was over pretty quickly.

That’s the transverse Secondary wave from a distant origin. It feels like you’re suddenly put on a ship rather than like the ground exploded. I learned that anecdotally…

Comparison: The 2011 earthquake had a magnitude of 9.0 - 9.1 (but it had a 7.2 foreshock 2 days before.)

https://en.wikipedia.org/wiki/2011_T%C5%8Dhoku_earthquake_an...

The thing most people don't mention is that after the March 11th 2011 earthquake, we had daily aftershocks, the kind you could easily feel, which lasted for months. Seems to happen mostly at night, most disconcertingly, as I was woken up out of bed more times than I could count with ones large enough to cause me to jump up and think the "big one" was hitting Tokyo.

Took me a good year, and moving out of Japan, to calm down about it and realize just how much daily stress it had caused me, how much on edge you are after something like this. Of course, nothing happened, but when your system is constantly in heightened awareness mode, the way I expect soldiers in a warzone feel wondering if there's someone around the corner waiting to get you, you start to build up PTSD in a real way.

Side note: add in a bit of nuclear fallout concern, plus having young kids and some playgrounds in Tokyo getting abnormally high enough readings they had to close them... oh, in addition to tainted food supply, and you'll maybe understand.

The Christchurch earthquake in New Zealand had a lot of aftershocks and a lot of people left the city to avoid them. Here is an article saying that there were 11,200 aftershocks in the following 2 years.

https://www.odt.co.nz/news/national/11000-aftershocks-christ...

Yep can confirm, I lived in Christchurch through the quake and aftermath. Aftershocks multiple times a day for months afterwards.

Living in the Bay Area and right atop a fault, I feel phantom shakes. I usually have my ham radio tuned to the local repeater and people start reporting real ones almost instantaneously. So I use that as indicator to calm myself.

Hasn’t affected my life but it’s always there in the back of my mind. I realised I’m also a lot more sensitive to them than anyone else I know. Almost all the major ones - including the one in Napa have woken me up, usually in cold sweat and heart palpitations.

I remember the aftershocks, and I still have ptsd regarding earthquakes. I've felt a few small ones back stateside and feels like it starts the cycle over again. Not sure how long it will take for me to get over it.

Start to accept that your just a human in a world not steered or controlled by humans, i always try to imagine being a astronaut looking back to earth and think:

Every single human ever born, and every single word ever written and every single day in history lived was on that small wonderful marble in the vastness of space.

What more can happen to you then to die? Living i fear.

We all have to die, but we don't have to live in fear.

talk to a doctor

Just curious, what would you expect to happen if they did?

I don’t exactly understand why he’s being downvoted. Perhaps he could have worded things better, but I read it in good faith.

A doctor may be able to tell them some specific coping mechanisms that could be helpful in breaking the thought loop they were otherwise unaware of, & sometimes a short duration of medication like a benzo can break the anxiety enough so that it doesn’t come back.

Obviously, it’s hard to tell over the internet, & that’s why it’s recommended to see a professional.

If he/she actually has PTSD-- which is entirely within the realm of possibility, there are medications such as Prazosin as well as therapy that can help.

We visited Japan 3 years ago and it stuck with me how normal earthquakes, alerts for this and tsunamis are.

Like wtf!

Japan is not only the country hit most frequently by a large margin, it is also the country hit by the strongest natural disasters.

It's certainly up there [1]. I didn't realize that Costa Rica and the Philippines were even higher than Japan.

According to [2] the US has the most severe weather in the world, which is interesting. I've certainly experienced some of it, tornadoes are horrifying.

I had a crazy experience in Oklahoma City once where I ran out of my hotel because of an earthquake only to see two funnels on the ground coming towards me.

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

[2] https://www.usatoday.com/story/weather/2013/05/16/extreme-we...

While I hope it is a small quake compared to the 2011 earthquake, the main 2011 earthquake came 2 days after a 7.1 foreshock quake:

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

https://en.wikipedia.org/wiki/2011_T%C5%8Dhoku_earthquake_an...

For those unware, the magnitude scales used to measure earthquakes are logarithmic, with released energy increasing by a factor of about 32 (10^3/2 to be exact) for each step. Thus, the 9.1 earthquake from 2011 released about 500 times as much energy as the one from today.

I feel like it should also be added that part of (not all) the reason we use logarithmic scale for these things to begin with is precisely because their "damage" or impact is not linearly correlated to the energy released from the event (same goes to dBPL used in sound pressure).

Unfortunately, it's not linear to the logarithmic scale either so it's hard to get a intuitive "feeding" from it.

I'd say it's something in between but closer to the linear scale in earthquake's case.

Hope today's was not the foreshock to something bigger.

Reminder that 9 isn't ~25% larger than 7, its 100x larger.

That was big. First time since the 2011 quake that I actually put the emergency backpack on. Another 10 seconds and I reckon we would have woken our son and headed outside.

what is the emergency backpack?

https://www.nhk.or.jp/sonae/en/goods/index.html

They also sell these in the US as well.

Products like this

https://www.homedepot.com/p/Ready-America-2-Person-3-Day-Eme...

They are good to have if you live in an area with natural disasters, 5-year shelf life and you just keep it somewhere that you can quickly grab if you ever need to evacuate.

Thank you! These are actually in stock locally and seem way more practical than the prepper food buckets.

HTTP Access denied from UK

Largest quake in at least a year in Japan. Also strangely almost exactly 12 months since a 7.0 in the very same area (20 March 2021): https://earthquake.usgs.gov/earthquakes/eventpage/us7000dl6y...

The infamous 2011 earthquake was also in March. Is there any plausible reason for earthquakes to occur in the same region around the same time of year over and over again, or is it just coincidence? I don't think Japan has any large glaciers that could melt in the spring and shift the center of mass of the plate underneath, for example.

My guess would be that ice melting in the caps triggers a release tension cascade in several parts of the crust, but is just a feeling. Less weight in the poles could make the planet tend to go more "sphaerical".

Just my own stupid theory. I'm not a geologist and could be wrong by a mile.

In any case since several years ago I have noticed a sort of end of the winter pattern: Eyjafjallajökull (2010), Fukushima (2011), Villarica Chile (2015), Fagradalsfjall (2021), New Zealand earthquakes (2022)... all in March.

And then is a waterfall later travelling towards equator: Volcan de Fuego Guatemala (may 2012). Feels a little like a tennis play with eruption waves bouncing, but maybe I'm just cherry picking facts together.

Interesting theory, but wouldn't the ice only melt at one pole cap at a time?

Good point. Dunno. Antarctic and Arctic are very different in terms of Geology. First is a continent with mountains. This means that has a thick crust. North Pole is submerged with some Islands around. Crust here is more thin and should be more prone to move when you remove weight or apply forces in any other direction.

Maybe thermal expansion, since March means warming after winter.

20 meters under ground there is already no temperature difference between summer and winter.

Great question. 1/12 x 1/12 x 1/12 -- odds seem kind of low...but could possibly be related to ocean currents, seasonal flow systems probably significantly shift the center of mass of large bodies of water, maybe related to temperature.

Probabilities and statistics don't work like that. Between 2011 and now there's been loads of earthquakes in Japan, in most months, many stronger than 7.0.

Heh :) That's totally incorrect. Do a search:

https://earthquake.usgs.gov/earthquakes/map/?extent=-32.6208...

That searches magnitude 7 and above for the last 24 months in a rectangular region that includes Japan and Taiwan. There's only been three, one was yesterday and two roughly a year ago in February and March.

So your intuition said arrogantly about earthquakes in Japan is incorrect, waay incorrect. Also I don't know if I got the probabilities totally right (but it seems fair for the probability of those other three earthquakes being in March, versus other months), but you said this as if you knew what you were talking about. But you don't. Seems like I'm the one here who knows what he's talking about, not you, sorry. Why not do a little research before you make your bold and arrogant claims trying to contradict someone else next time?

To get any meaningful results, we'll need a decent sample size. Magnitude 7.0+ quakes in Japan are a fairly rare phenomenon, occurring 1-2 times per year. If we pull out a somewhat larger data set of 136 such quakes in the last 100 years (https://www.volcanodiscovery.com/earthquakes/japan/largest.h...), we'll notice that the quakes are fairly evenly distributed between the months.

The mean is (of course) 8.33%, and the standard deviation 1.91%. All months fall within 2 standard deviations from the mean (March is highest at 11.62%, followed by Feb at 11.06%, Jun 10.51% and Nov 9.76%). So, nothing particularly interesting to see here. Also, if we do the same "three-month window" analysis you did, the winner is February (with 30.68%, somewhat higher than the expected 25%).

Wow, I just checked out that website and I can't believe you did that analysis! That's pretty awesome. You somehow got the data out of that site, and analyzed it.

But I did a quick sanity check on your numbers (searching on that site quakes from March 18 1922 to March 18 2022) and there are actually 153 quakes 7+ (not 136). If you share the raw data it will be more convincing!

Unless you do I'm going to take my 10 year sample from 2011 with a 68.75% of chance of quake in March (+- 1 month) as gospel :)

So pretty hard to predict and essentially random, meaning predicting when a given quake will occur should be, extremely challenging, essentially predicting a random variable, which would be pretty incredibly amazing. Good to see.

As a further update, consider this search:

https://earthquake.usgs.gov/earthquakes/map/?extent=16.80454...

All quakes 7 and above from 2011-01-01 until today. Some stats:

Total quakes - 16

Number of quakes in March - 6

Number of quakes in April - 3

Number of quakes in February - 2

Months with 1 quake - 5, 7, 8, 10, 12

Probability of quake in March - 37.5%

Probability of quake in March (+- 1 month) - 68.75%

Interestingly the two biggest earthquakes in my memory in Mexico City happened in the same day. Sept 19 1985 and 2017

Every year in Sep 19 there is a city wide simulacro. And then in 2017 an earthquake happened for real.

Maybe something to do with orbital forces / sea currents...?

I felt a 3-ish small one for about 5 seconds and then it was over. About a minute later it began again but this time it was definitely over 4 (I’m in Tokyo). It was long too, almost a minute I think (by the end it was not so strong, maybe 4-5 during the first 15 seconds or so)

Just to clarify for others, the numbers used in the above post are shindo-scale which are a location-dependent measurement of actual movement. They are used much more in Japan versus magnitude numbers.

i used to live very close to a fault in Los Angeles County, and the numbers i remember from the 80s and 90s don't seem to correlate to the numbers i hear now - i left CA in 2006. The running joke with my CA friends is "don't even tweet/post about it unless it's a 7.0" whereas a 7.0 would mean widescale destruction back when i lived there. I remember the Apple Valley Quake, it was a rolling quake, and it was somewhere between a 4.8 and a 5.4. It derailed trains, and caused a bunch of property damage. I had a ham radio at the time and i was tuned into two of the biggest repeaters in southern california (one being "the nut") and listened to the damage reports and movement of emergency crews.

We were quite far from that one, and it wasn't violent, but it still caused property damage and power outages due to shorted lines.

So i see a 7.3 magnitude, and since i no longer deal with earthquakes (just floods, hurricanes, and tornadoes), i have no frame of reference for how bad that is. Gauging off the running joke above, it's gotta be somewhat bad, right?

I'm no expert, but it looks like the Apple Valley big earthquakes were centered on land, and these Fukushima are centered off the coast. I would assume the closer to the center, the worse the damage, so perhaps that could explain it?

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

It looks very close, is a tsunami possible?

Yes: https://tsunami.gov/?p=PHEB/2022/03/16/22075004/1/WEPA40

Also, from Japan: https://www.jma.go.jp/bosai/map.html#5/38.411/143.174/&elem=...

It looks like the tsunami's arrival will be before high tide, so at least they have that going for them...

edit: Misread, I apologize

It is. I think you misread the previous comment. Tsunami will hit before the high tide, resulting in less potential for flooding.

1m rise is expected, said the news.

less than 1 week difference 11 years later.

Do we have to worry about the nuclear plant? Is it still active?

It's not active.

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

No, I don't think that plant will ever be active again. There might be a danger if a tsunami came through again and washed more radioactive debris out from where it settled.

We do have to worry about the nuclear agency that allowed it to be built there in the first place ...

Right on schedule.

Chip plants and nuclear plants in high seismic activity land

People who gave the greenlight should be in jail for the rest of their lives

All nuclear plants survived for many earthquakes, but F1 failed for a tsunami.

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