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M7.4 quake in northeast Japan likely caused by 2021 temblor: experts

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M7.4 quake in northeast Japan likely caused by 2021 temblor: experts

This is just wrong headline. The two quakes are caused by a sinilar phenomenon/event or movement of the earth’s crust. One quake is not the cause of the other.

8 ( +14 / -6 )

It is also in the same area as the 2011 mega quake. The regular smaller quakes are a good thing. The relieve tension in the plate. However, it is impossible to accurately predict quakes or their intensity. Japan lays on the cusp of three plates. It has always had earthquakes. The only accurate prediction one can make is, Japan will continue to have earthquakes.

7 ( +8 / -1 )

A prognosis is not always so bad that there cannot be some continued quality of life.

Like a brain aneurism, we know the faults exist, where they are most prone to occur and the likelihood of more damage IF precautions are not taken in advance.

People just need to make every practical effort to stay safe in the meantime.

6 ( +9 / -3 )

All you can really do is have a few boxes of bottled water, a tent and a camp stove, tins of food. Even then your house could collapse making it impossible to get to. My family have a meeting place, those that survive will meet there. If it goes totally bad that’s all you can do. You might not be able to get to that grab bag. A Disaster will catch even the most prepared unawares. Just getting out of the rubble alone might prove too much. But be prepared.

6 ( +7 / -1 )

I noticed that the only good comment was totally ignored

JustaskingToday  05:37 pm JST

Is correct in the fact the article and tittle are incorrect in stating one Tremblor cause the other Tremblor a year later.

My guess is poor translation from Japanese, a fault line a volcano, etc .cause earthquakes not earthquake cause earthquakes.

4 ( +7 / -3 )

This is just wrong headline. The two quakes are caused by a sinilar phenomenon/event or movement of the earth’s crust. One quake is not the cause of the other.

No, the headline is correct. Geologists consider this most recent quake and the one in February to be part of the aftershock sequence of the Great Tohoku Earthquake. it is also not unheard of for one quake to trigger another nearby, in this case the February quake triggering the March quake. I have lived through that sort of earthquake sequence and it wasn't very long ago either. In our case the second and much more powerful of the two quakes was actually four separate ruptures that happened more or less in a line seconds apart as one movement triggered another. Each rupture was in essence it's own separate earthquake but they happened seconds apart and caused a ground rupture many kilometers long.

3 ( +3 / -0 )

a fault line a volcano, etc .cause earthquakes not earthquake cause earthquakes.

There have been numerous instances in history of one quake causing subsequent quakes. One great example is the earthquake sequence along the New Madrid Fault between 1811 and 1812 including at least three quakes of M7.0 or greater. There is currently a fear that this earthquake sequence loaded another major fault system, the Wabash Valley Fault along the Illinois - Indiana border.

There is concern the 2019 earthquake sequence in Ridgecrest CA (where the first quake very much triggered the second larger quake) has loaded the nearby Garlock fault. The Garlock Fault intersects the San Andreas Fault and the fear is a quake on the Garlock Fault could trigger a devastating quake along the San Andreas Fault comparable to the massive Tejon Quake in the lattere 1800s, a quake that was itself triggered by an earlier quake on the Garlock Fault that was triggered by a quake in Death Valley.

If you study the Eastern California Sheaer Zone out in the Mojave Desert you find the 1992 Landers Quake triggered the Big Bear Quake the same day. It also loaded faults in the ECSZ that in turn caused the 2002 Hector Mine Quake. That quake is in part responsible for the Ridgecrest quake series. Movement on one fault loads up other faults, leading to more earthquakes. What is happening in the ESCZ is interesting as the boundary between the North American Plate and Pacific Plates is moving east, from the San Andreas to the eastern side of the Sierra Nevada along what is called the Walker Lane.

3 ( +3 / -0 )

In our earthquake sequence, what turned out to be the foreshock to the main quake was M6.4. It ruptured three different short fault lines, two of which were in line with each other but the third was perpendicular, at right angles, to the other two. Real head scratcher geologists had never seen before. The ruptures made a nice big I in the ground. The second main quake occurred on four basically unknown fault segments that linked together during the quake to form one long rupture. That rupture more or less died out as it met a volcanic field where the rock is more elastic due to the high heat (this volcanic field is a lot of mudpots and fumaroles. We have some interesting geology nearby.

3 ( +3 / -0 )

a fault line a volcano, etc .cause earthquakes not earthquake cause earthquakes.

One earthquake can release/increase pressure on a fault line, which can lead directly to another earthquake.

I don’t know if that’s what happened in this case, but it was widely accepted that the Niigata earthquake on the 12th March 2011 was a direct result of the massive release of pressure caused by the major earthquake of the 11th.

2 ( +6 / -4 )

If you don’t mind, with proper acknowledgement to the source, may reference it again in other posts. - Regards.

USGS - US Geological Survey.

2 ( +3 / -1 )

Another 4.4 off Miyagi at 10:05pm JST. - NHK & Yomiuri reporting no indication of tsunami at this point.

* *If only we had an “earthquake map” and/or all those “pre*-caution advice ‘apps’ recommended earlier to tell us … ‘*when***’.

1 ( +4 / -3 )

This is a global earthquake map. You can zoom in as close as you wish. You can click on each quake for additional detail. I have it bookmarked. It's a great resource.

https://earthquake.usgs.gov/earthquakes/map/?currentFeatureId=nc73707451&extent=-43.06889,-232.03125&extent=78.83607,135.70313

1 ( +2 / -1 )

Have to acknowledge that site is quite colorful but seems somewhat limited to just this part of Asia.

Will keep it though for future reference: https://earthquaketrack.com/p/japan/recent

1 ( +2 / -1 )

Well then, pardon my fault, sir, My sincere & humble apologies for any unintentional oversight. - It is equally thorough with it’s little ‘Search’ box.

Acknowledged and will keep it also for future reference:

https://earthquaketrack.com/p/japan/recent -*****

(**additional links to other regions across the world within*.)

1 ( +2 / -1 )

A very interesting link @DesertTortoise 9:06am. Your earthquake map and app are quite useful & well presented. (Seems you always have the most extensive, practical knowledge & experience on many topics.)

If you don’t mind, with proper acknowledgement to the source, may reference it again in other posts. - Regards.

@DesertTortoise 9:06am: “This is a global earthquake map. You can zoom in as close as you wish. You can click on each quake for additional detail. I have it bookmarked. It's a great resource.

https://earthquake.usgs.gov/earthquakes/map/?currentFeatureId=nc73707451&extent=-43.06889,-232.03125&extent=78.83607,135.70313 -
0 ( +2 / -2 )

And thanks again for you kind concern for family & friends in Wakayama. Everyone is safe.

zichiToday  12:21 am JST

snowymountainhell

People just need to make every practical effort to stay safe in the meantime.

Listening to the ancients when deciding where to live. The map was useful for that. How about in Wakayama you get many quakes there?

0 ( +2 / -2 )

Oh look, my diagram of the fault rupture changed. Let me try again. The foreshock ground rupture was sort of T shaped. I .

0 ( +2 / -2 )

Successive quakes are results and could originate from the same source, but still one can't be a cause of another.

Please do some additional study. The June 1992 M7.3 Landers Quake is a classic example of a quake starting on one fault causing other faults to move, making for a longer and more intense earthquake. By means of a cascading rupture whereby the rupture of one fault triggers the rupture of a neighboring fault, the Landers main shock ruptured five separate fault segments in sequence: Johnson Valley, Landers, Homestead Valley, Emerson, and Camp Rock. The Landers quake is therefore also sometimes referred to as "the Landers sequence." The total length of the rupture was approximately 80 kilometers. It is thought that the complex network of five right-lateral strike-slip faults had not experienced a major rupture in thousands of years, although the Homestead Valley segment had experienced a surface rupture singly 13 years prior. That sequence of ruptures caused the M6.4 Big Bear Quake a few hours later on a separate but unrelated fault some 40 kilometers distant. There is some dispute whether or not Big Bear was an aftershock to the Landers Quake or its own quake. The Big Bear fault could be considered conjugate to the five faults that slipped during Landers, meaning that Big Bear's left-lateral strike-slip intersected or maybe nearly intersected with the right-lateral strike-slip faults involved in Landers. Conjugate faults sometimes slip within hours or days of each other, causing pairs of earthquakes.

During the years following Landers, seismicity within the aftershock vicinity gradually decreased from its immediately heightened state, as would be predicted by the Omori law decay, an empirical relationship describing the decay in the rate of aftershocks over time. Then, a full seven years after Landers and 30 km, or 18 miles, to the northeast, the M7.1 Hector Mine quake struck on October 16, 1999, when seismicity in the region was decreasing but still higher than before the Landers earthquake. Deemed a separate event initially, as was Big Bear, the Hector Mine quake is now considered a triggered event. The seven-year delay is attributed to a complex viscoelastic stress buildup on the Hector Mine fault due to the relaxation of the earth's lower crust and upper mantle in response to the Landers earthquake.

Like Landers, the Great Tohoku Earthquake was not one rupture on one fault but rather four separate faults ruptured in sequence seconds apart in the deep trench off the coast of Japan. And the aftershocks from that quake continue 11 years later.

0 ( +1 / -1 )

No, the headline is correct. Geologists consider this most recent quake and the one in February to be part of the aftershock sequence of the Great Tohoku Earthquake. it is also not unheard of for one quake to trigger another nearby, in this case the February quake triggering the March quake.

Quakes are a result, not the cause. The causes of earthquakes are movement of plates, friction, pressure release from volcanoes, tension release etc.

Successive quakes are results and could originate from the same source, but still one can't be a cause of another.

-1 ( +1 / -2 )

IF precautions are not taken in advance. 

Precautions not taken in advance?

When else would you take a precaution?

I read that a good precaution for a big quake is to reinforce walls. They could come down or close in or something like that.

-2 ( +4 / -6 )

@zichi

Very interesting link.

The lines on the graph were useful and well presented.

-3 ( +1 / -4 )

@zichi

Yes, precautions are very important. Very sage advice.

As you said we should be prepared. It is very hard to predict when or where they’ll hit.

-5 ( +1 / -6 )

One earthquake can release/increase pressure on a fault line, which can lead directly to another earthquake.

Why was I not surprised by this.

So did the fault cause it or the earthquake?

Now think hard,

-5 ( +3 / -8 )

So did the fault cause it or the earthquake?

Now think hard

You have a row of dominos lined up. Knock the first one over. What causes the last domino to fall, gravity, or the adjacent domino hitting it?

Think hard.

-6 ( +2 / -8 )

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