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12 injuries reported from Saturday night's quake

14 Comments
By MARI YAMAGUCHI

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14 Comments
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I saw some people get injured from falling out of a packed train when the doors opened after the train delay. I assume they didn't add them in the statistics.

-3 ( +3 / -6 )

590km depth ... that's already in the earth' mantle. I wonder what caused the earthquake in such a depth? Must have been a giant geode collapsed or something.

3 ( +3 / -0 )

Living with geothermals seems to be safer than Fukushima style reactors. When will the concrete heads notice.

7 ( +9 / -2 )

Most of Japan? Really? I hardly ever miss quakes, even small ones. Didn't feel a thing. And I was either shopping at Don Quixote at the time or eating sushi in a crowded restaurant. I saw no reaction in anybody. And I am a lot closer to Tokyo than Hokkaido.

-2 ( +0 / -2 )

I wish Japan would stick to one method of describing the magnitude of earthquakes. I've now read that the first one on Saturday evening was 4, 5 and now 8. Which was it?

-5 ( +2 / -7 )

I wish Japan would stick to one method of describing the magnitude of earthquakes. I've now read that the first one on Saturday evening was 4, 5 and now 8.

The magnitude is an indication of the size of the disturbance, in this case 8.1. The intensity is an indication of how much shaking it causes, and that differs depending on where you are. Generally speaking, the closer you are to the epicentre, the stronger the shaking and the higher the intensity. A 7 is potentially devastating, a 5 or 6 is pretty scary, a 4 makes you sit up and take notice, a 3 is ho-hum, a 1 or 2 you might not even notice.

See how the different colours show the different intensities from the same earthquake - http://www.jma.go.jp/jp/quake/20150530203436395-302024.html

7 ( +7 / -0 )

I wish Japan would stick to one method of describing the magnitude of earthquakes. I've now read that the first one on Saturday evening was 4, 5 and now 8. Which was it?

Notice the difference between magnitude and intensity ("shindo"). I think the Japanese way of describing earthquakes is really useful. A magnitude 8 earthquake out in the ocean somewhere might be felt in, say, Tokyo as a "shindo" 3, which is nothing to worry about. The shindo / intensity number gives you the real story. Now, whenever I hear of an earthquake I look for the shindo rating.

7 ( +7 / -0 )

And I am a lot closer to Tokyo than Hokkaido.

The quake was closer to Tokyo than Hokkaido.

I wish Japan would stick to one method of describing the magnitude of earthquakes. I've now read that the first one on Saturday evening was 4, 5 and now 8. Which was it?

I agree with hatsoff, and for people living in Japan it is helpful to know and understand the differences between the two methods of explaining or defining an earthquake.

The magnitude describes the strength of the earthquake at it's epicenter, the Japanese method of using the "shindo" explains or warns people about the actual strength at their location.

An 8.5 magnitude earthquake in the middle of the ocean may only cause a 3 or 4 on the Japanese scale as it describes the strength at the location of the sensor not the epicenter.

I for one am glad for both methods, and anyone for anyone living here it helps to learn the differences.

2 ( +3 / -1 )

Cleo, hatsoff and Subaru are right. The "M" ratings are, for all practical purposes, meaningless. Only the Japanese Shindo scale is useful. So, if you want just one system, ignore any earthquake rating with an "M" after the number.

2 ( +4 / -2 )

590km depth ... that's already in the earth' mantle. I wonder what caused the earthquake in such a depth? Must have been a giant geode collapsed or something.

Excuse me a giant what?

The earthquake occurred deep in the subduction zone between the Pacific tectonic plate and the Philippine sea plate. This is really not a surprising depth in any way, such earthquakes do occur often in subduction zones.

-2 ( +1 / -3 )

Little shaking is just for reminder to be prepare for big one anytime...

0 ( +0 / -0 )

Earthquake scales are pretty much all meaningless from a safety point of view, because the shaking will start a few seconds after the initial warning. If fact, there was no warning for this quake because the system is set to send warnings for quakes under 150 km depth.

Magnitude is not meaningless. The moment magnitude scale represents the amount of energy released. If there is an 8.5 quake at a shallow depth out to sea, there is a very real possibility of a tsunami. Once I saw the depth of this one I knew there was no chance of a tsunami or aftershocks. Deep-focus quakes are scary because they are felt over a wide area, but in reality they are far less dangerous than shallow quakes.

Still, a deep-focus quake of M 8.1 is a very rare event. The largest one ever recorded is 8.3.

0 ( +0 / -0 )

This is really not a surprising depth in any way, such earthquakes do occur often in subduction zones.

Except that the specialists invited by NHK commented that this was an extremely rare type of earthquake, especially given it's tremendous power. I tend to believe him....

0 ( +1 / -1 )

@daito_hak you want to tell me about subduction zones but you don't even know what a geode is? Let me guess: you just looked that up on Wikipedia so you appear smarter than you are.

0 ( +0 / -0 )

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