Did high magnitude (mag 6+) earthquakes indeed disappear for a 30 year period (1975 - 2005) ?

As most of you are probably aware of by now, there was yet another major earthquake (7.2) experienced in the Alaska region today (24 June, 2011).
Now like many of you, I personally feel that we have been experiencing an increasing trend in the number of such high magnitude earthquakes occurring around the world in just the last few years ... Indonesia, Chile, New Zealand, Japan, etc. Sure, one can always try to explain this as simply a correlation with the increasing ease with which information (and news especially) becomes almost instantly accessible to us.

So, out of curiousity, I decided to get the very useful Wolfram Alpha online data query program to run a search and report back on the number of earthquakes higher than magnitude 6 that have occurred in the time period beginning 1900 to the present date and present it as a graph ... imagine my surprise when I took a look at the resulting graph.

[atsimg]http://files.abovetopsecret.com/images/member/a243b857be7f.jpg[/atsimg]

I've put a black circle around the period from 1975 to 2005 to emphasize the part of the graph that you should pay close attention to.

As is obvious, there was almost a constant number of high magnitude quakes recorded from 1900 all the way through to 1975.
Then for some unknown reason, the number of high magnitude quakes occurring dropped dramatically over the following 30 years ... from around 1975 to 2005. Such was the scale of the drop in high magnitude quakes, that it gives the impression that a chunk of the graph is missing.
Come 2005, and after a 30 year lull, high intensity earthquakes began to occur again ... and occur they did with a vengeance !

Obviously there could be a number of possible explanations for the 30 year "lull" ... such as Wolfram Alpha is not accessing EVERY earthquake report during that 30 year period or records for that 30 year period are missing/incomplete, etc, etc.

But another possibility we have to consider is that in fact, during that 30 year period (1975 - 2005), that the number of high magnitude earthquakes did indeed drop precipitously and that Wolfram Alpha is reporting (and displaying) accurate information.

If so, then I personally am at a loss to come up with a scenario whereby we can have a steady number of high magnitude earthquakes occurring consistently from 1900 to 1975 (over a 75 year period), and then virtually NO high magnitude earthquakes for the next 30 years. In fact, the 2 highest magnitude earthquakes in 111 years didn't happen until immediately AFTER that 30 year "quiet period" ended.

So my question ....

What changed or happened in 1975 to "turn off" high magnitude earthquakes ... and what changed or happened in 2005 to "turn on" high magnitude earthquakes again ?
Is this an actual effect ... or just a glitch in the data ?

Gotta admit that the graph sure does look suspicious for that specific time period. Would be great if we could somehow manually check that time period and confirm or deny that the number of really big earthquakes actually did reduce significantly in number. If confirmed, then we have a major puzzle on our hands wouldn't you say ?

Good spotting !

The graph does look impressive and you may be on to something here. But don't forget the Sumatra earthquake in 2004, which had a magnitude between 9.1 and 9.3 on the Richter scale.
Maybe this one was the beginning of a more geologically active period on earth.
Here's the link of the Sumatra EQ:
en.wikipedia.org...

Originally posted by Imogene72
The graph does look impressive and you may be on to something here. But don't forget the Sumatra earthquake in 2004, which had a magnitude between 9.1 and 9.3 on the Richter scale.
Maybe this one was the beginning of a more geologically active period on earth.

Even though I personally chose 2005 as looking like the end of the "lull period", you could be quite correct and that it was in reality the previous year of 2004. When looking at the axis of the graph, it's pretty difficult to tell the difference between 2004 and 2005 :-)

The world just got done testing hundreds of nuclear weapons around the world......all over the world.


The nuclear blasts themselves could have released energy from the Earth.

So maybe a nuclear war now will keep Supervolcano Yellowstone from errupting? Maybe.

Or maybe A God was happy how the United States was between '75 and 2005....and a period of calm started.

Appears God isn't happy now....especially at the United States

reply to post by tauristercus


Yeah, it can be confusing! Where did you find this chart anyway? And most importantly, what the @#$& does it mean??? How can we explain such a decrease? And why aren't scientists - seismologists all over it?!!

Hey, here's another link I found regarding this matter (actually, it's a book on EQs) which confirms the chart you posted!
books.google.gr... yrYqMyYLn0IE&hl=el&ei=oXIETty9Hc3vsgb2kJnYDA&sa=X&oi=book_result&ct=result&resnum=2&ved=0CCMQ6AEwAQ#v=onepage&q&f=false

reply to post by tauristercus


I think there may be an anomaly with that earthquake graph..or not?

USGS shows 4031 with the same parameters.

Originally posted by Imogene72
reply to post by tauristercus

 

Yeah, it can be confusing! Where did you find this chart anyway? And most importantly, what the @#$& does it mean??? How can we explain such a decrease? And why aren't scientists - seismologists all over it?!!

I used that incredibly useful (and most importantly ... free) data query engine called Wolfram Alpha from the people who created Mathematica which is used by scientists, mathematicians, etc worldwide ... brilliant product.

Go to WolframAlpha.
Then type the following search query earthquakes magnitude > 6 from 1900 to 2011 and press enter. A few seconds later WA will finish processing your request and display the graph.

As for what it means ... I have no idea.
The way I look at it, it could go 2 ways. Firstly, WA stuffed up the search request and missed a lot of data between 1975 and 2005, accounting for the dramatic drop in high magnitude quakes in the graph ... or secondly, something VERY unusual geologically was happening to the Earth during that 30 year period.

Originally posted by Chadwickus
reply to post by tauristercus

 

I think there may be an anomaly with that earthquake graph.

USGS shows 4031 with the same parameters.

Can you requery and determine how many neic reported earthquakes occurred ABOVE magnitude 7.0 ?

The WA graph I posted seems to indicate that within that 30 year period, almost every earthquake (except for a handfull) were primarily mag 7.0 or less.
If you only get a very small number of quakes higher than 7.0, that would tend to validate the Wolfram Alpha graph as being correct.

reply to post by tauristercus


I got 412 with > 7.0.

Does seem low, although that's an average of 13 a year.

reply to post by Chadwickus


Yes it is, especially if you think that for the past 5 years, we've had an average of 150 EQs above 6.5 per year

reply to post by tauristercus


Cool, I 'll try it out, thanks

Originally posted by Chadwickus
reply to post by tauristercus

 

I got 412 with > 7.0.

Does seem low, although that's an average of 13 a year.

edit on 24/6/11 by Chadwickus because: (no reason given)

Does that average of 13 a year still hold true for the years 1900 to 1975 ?

[atsimg]http://files.abovetopsecret.com/images/member/e9d727173448.png[/atsimg]

The trend doesn't look nearly so obvious when one includes the other magnitudes.



Additionally if one looks at the whole trend
over a larger period of years, one finds that the
earthquakes are increasing in magnitude and frequency.


[atsimg]http://files.abovetopsecret.com/images/member/96699ee40d98.png[/atsimg]



Both these graphs were taken from a website
that discussed the rapture back in April.
rapture ready / earthquake graphs



David Grouchy

reply to post by tauristercus


Not sure, the further back we go, of course the reliability of reports reduces...

What may be interesting is that the 70's is when the Richter scale was phased out and changed to what we know as magnitude to measure earthquake intensity.

May be a coincidence, I dunno?

Not sure how relevent this is but I came across this while researching the topic.

Then, in 2004, a magnitude 6.0 quake rattled the town of Parkfield, California, also known as the seismology capital of the world. Here, where the San Andreas Fault cuts through central California, a magnitude 6.0 quake has occurred roughly every 22 years for about the last 100 years. The 2004 quake happened after a 38-year lull, and geologists were ready with an extensive network of instruments and boreholes that record every seismic hiccup in the area.

Full article.

reply to post by Pervius


Idiocy.

From the point of view of God why would he be more upset at the left side of his leg then the right side. In fact God probably doesn't even know/care you exist that's if he himself exists.

Activity on the sun is going through a decline, the Earth is waking back up to take up the slack. I don't know what it means for us but in the larger scheme of things I think the Universe would be better off without us in it.

reply to post by tauristercus


can you find number of meteors entering atmosphere 1900 to 2011?

Originally posted by amaster
Not sure how relevent this is but I came across this while researching the topic.

Then, in 2004, a magnitude 6.0 quake rattled the town of Parkfield, California, also known as the seismology capital of the world. Here, where the San Andreas Fault cuts through central California, a magnitude 6.0 quake has occurred roughly every 22 years for about the last 100 years. The 2004 quake happened after a 38-year lull, and geologists were ready with an extensive network of instruments and boreholes that record every seismic hiccup in the area.

Full article.

You should get more stars for this find... this is an important admission/observation that matches the data, which should be considered a correlation.

As the OP points out.... what could have caused the lull and then the sudden increase again?

S&F!

~Namaste

reply to post by tauristercus

Interesting thread, S&F.
I guess that you'll like my thread Are Earthquakes Really on the Increase? Study and facts, with lots of graphs and statistical studies.