Why is Japan still getting 6.0+ quakes, 13 days later?

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posted on Mar, 24 2011 @ 04:20 PM
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Hey guys,

I'm just looking for an explanation as to why Japan is still getting quakes, as strong as 6.6, 13 days (and counting) after the 9.2? Are these aftershocks? Do aftershocks usually last this long for a quake of this magnitude?

Thanks for any info you can give me.
edit on 24-3-2011 by Ryanssuperman because: (no reason given)




posted on Mar, 24 2011 @ 04:26 PM
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Aftershocks can go on for months. Chile's earthquake for example had aftershocks that went on for a while. Not exactly sure how long but you can Google it.

It was a 9.0 that hit Japan btw.



posted on Mar, 24 2011 @ 04:26 PM
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I know aftershocks can hang around for a while so I looked for this answer two days ago and thought the formulas on wiki interesting.
It seems if you plug in the numbers a 6.0 aftershock is pretty plausible for a very long time even though the probability "decays".

en.wikipedia.org...



posted on Mar, 24 2011 @ 04:31 PM
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I don't think the USGS visits this site, but...
There are how ever some interesting laws and theories. The URL below shows the main 3.

en.wikipedia.org...


The General idea is, the bigger the quake, the bigger and more often the aftershocks. I remember lots of shaking and finally days later getting used to the aftershocks after the 1989 Loma Prieta quake.



posted on Mar, 24 2011 @ 04:45 PM
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Aftershocks will happen for months after a large quake

I live in Christchurch, New Zealand where we had a 7.1 quake in September.
We have had over 5000 aftershocks since then. The largest was a 6.3 on Feb 22 that devastated the central city and killed approx 185 people.

The experts here were saying the Japan quake was some 8000 times stronger than our big one.
The aftershocks from a mag 9 quake will be felt for a long time to come..



posted on Mar, 24 2011 @ 05:00 PM
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Originally posted by Brogue
Aftershocks will happen for months after a large quake

I live in Christchurch, New Zealand where we had a 7.1 quake in September.
We have had over 5000 aftershocks since then. The largest was a 6.3 on Feb 22 that devastated the central city and killed approx 185 people.

The experts here were saying the Japan quake was some 8000 times stronger than our big one.
The aftershocks from a mag 9 quake will be felt for a long time to come..



The destruction of Christchurch was not an aftershock. It started from another fault. I can't source that, but I remember seeing it on some articles when it happened.



posted on Mar, 24 2011 @ 05:34 PM
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reply to post by Gab1159
 


according to geonet, the 6.3 is an aftershock from the september quake:

"Seismologically, this is classed as an aftershock because of its relationship to the ongoing activity since September last year. Its occurrence was always statistically possible, but the long time interval and slow decrease in general activity had made it less likely. Unfortunately, it has happened after all and in a location that has brought the worst result."

www.geonet.org.nz...



posted on Mar, 24 2011 @ 07:13 PM
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Originally posted by Ryanssuperman
Hey guys,

I'm just looking for an explanation as to why Japan is still getting quakes, as strong as 6.6, 13 days (and counting) after the 9.2? Are these aftershocks? Do aftershocks usually last this long for a quake of this magnitude?

Thanks for any info you can give me.
edit on 24-3-2011 by Ryanssuperman because: (no reason given)


An answer from my dad, seismologist with the USGS:

After shocks:
After a main EQ (the 9.0 in the case of Japan's recent big one), the plates involved continue to adjust to their new states of stress. These adjustments cause more earthquakes--the aftershocks. All other things being equal, and on average, there are lots of aftershocks at first then they slowly die off with time. The falloff is commonly exponential (same formulas as for compound interest only in reverse).

Again on average, within a year of the main EQ, the fault will produce one EQ, one magnitude less than the main EQ. So Northeast Japan could expect an after shock as large as M8, which might cause a smaller Tsunami.

10 aftershocks two magnitudes less (M7)

And 100 aftershocks as large as M6.

and so on down the magnitude scale.



posted on Mar, 25 2011 @ 08:28 AM
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reply to post by Ryanssuperman
 


I also posted the answer (and quoted your question) in the Quake Watch thread:

www.abovetopsecret.com...

Hope that is ok with you?



posted on Mar, 25 2011 @ 08:39 AM
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reply to post by ns9504
 


Tell your Dad thank you. I was wondering just now about Japans aftershocks and how much longer they would go on and why they were so large.

Here in Washington a 2.0 get's the news media scrambling for hours looking for any broken knickknacks to report...they seriously over react to little shakes here.



posted on Mar, 25 2011 @ 08:49 AM
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Here I ploted a graphic with the last 2 weeks of Japan Earthquakes. The recent ones are on the left side of the graph. It does not look very much like we have a strend for the earthquakes to reduce in intensity.





posted on Mar, 26 2011 @ 07:09 PM
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I did not plot the last 2 days , however it appears to calm down with the frequency and intensity of the Japan quakes. I guess we will go into normal range very soon.

By the way , in the last 30 days we had 1159 earthquakes above the magnitude of 4, quite some shaking!

PS: about the graph above, I forgot to mention that the magnitude of the earthquakes is on the Y axis, time (2 weeks) is on the X axis.
edit on 26-3-2011 by Romanian because: (no reason given)



posted on Mar, 27 2011 @ 06:02 PM
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So how long until these eqs go into the 4 to 3 range? B/c I must say its aweful timing for the 6.5 magnitude eqs.





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