For the journal-readers: Earthquakes and Isostasis

[Dogmudgeon]

There has been a spate of earthquakes in recent months -- actually, over the past few years. So I have a few questions for the geologists and literate lay readers with access to current geological work. (I also want to open the topic for discussion, so if you give me any of that "Google-is-your-friend" snark, you will be flamed. :P )

First, has the number and intensity of the earthquakes really increased, or is it all an artifact of reporting?

Second, has there been any scientifically-supported speculation or work to examine whether this is happening due to isostatic changes from the loss of ice on Greenland, Siberia, Alaska, and Antarctica?

Background:
Isostasy at Wikipedia
Post-Glacial Rebound at Wikipedia
Sea Level Change at Wikipedia

--p!

[phantom power]

1. If not now, it would seem like only a question of when.

Antarctica and Greenland in particular ought to start floating higher on the mantle, if enough ice melts away. It seems inconceivable to me that a mass distribution of that magnitude would not result in seismic activity. Probably pretty major seismic activity.

[Geostudent]

2. Some Information

First, some information and lists on earthquake frequency.

As you can see, that is from data collected since 1900.
You can use this USGS Site to search for earthquakes of specific magnitude. I do not have time to run the numbers at this moment.

On the issue of isostatic rebound, the effects would be more local. You would be seeing quakes in the areas where the ice is melting. I personally have not heard of any major quakes in area such as Greenland or the Antarctic.

Earthquakes do happen after/during the lessening of the ice sheets due to isostatic rebound. I read of an 8.2 earthquake in Scandinavia in the past due to glacial rebound.

Over all, you question seems to focus on the issue if the melting of the ice caps and the corresponding rebound could cause earthquakes a great distance away. The first question is are the ice caps melting. Recent research has shown in the mass balance of the Antarctic Ice sheet is probably increasing. (Source: Mass balance of the Antarctic ice sheet
Wingham, D.J. ; Shepherd, A. ; Muir, A. ; Marshall, G.J. Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, Volume 364, issue 1844 (July 15, 2006), p. 1627-1635)
If the mass balance was increasing, then there would not be any rebound.
As for Greenland, discusses the mass balance of Greenland. I have not read it, but the abstract notes that there is a loss in Greenland.

Research or speculation on your specific question does not exist to my knowledge.

[Dogmudgeon]

5. Welcome to DU!

Thanks for making my post the first one you replied to!

The links are quite useful, and thanks for posting them. In particular, I was not aware that the overall mass of Antarctica was increasing. I wonder if we can expect this to continue much longer. I also neglected to consider local seismic activity.

I'm sure there are still many surprises in store.

Thanks, and again, welcome to DU.

:hi:

--p!

[GliderGuider]

3. I suppose you also don't want any snark about

Russian Scalar Energy Weapons Causing Earthquakes either, right?

http://www.prahlad.org/pub/bearden/scalarvocanos.htm

I do not know what the statistics are but it seems that there are alot of volcanoes going off lately. An at least two very gigantic earthquakes in the past week or so. Having done a good deal of reading at scalar scientist Tom Bearden's website Cheniere.Org I cannot help but wondering if any of this earthquake and volcano activity is being cause by the new scalar electromagnetic superweapons called "Longitudinal Wave Interferometers," or "Tesla Howizters."

According to Bearden the covert development of these devices, in at least 10 countries, began decades ago, especially in Russia, whose scientists were more able than those in the West to think outside the box of conventional electromagnetic theory, a theory which is incomplete. Scalar electromagnetics restores certain equations which were thrown out along the way to "make things simpler," and announces the amazing fact that what we call the vacuum of space is actually an ocean of energy. The energy is there in incredible abundance once you know how to tap it. Energy which could change the world for good, and also energy which can be made into fantastic weapons. Weapons such as no warrior has ever dreamed of in his wildest imagination.

What is the the point of this post? None, of course. It has Zero Point...

[CabalPowered]

4. While we have lots of data, our instruments only provide a basic

look at what's actually happening. I don't think it's safe to assume the number of quakes is on the increase, as there has been an increase in the number of instruments deployed. Lots of data is good for statistical analysis but I don't think it gives us a complete picture.

The latest instruments under development could change that. The experimental spectrograms deployed in the Cascades are really interesting. Today provides a good example with the 7.4 in Jakarta. With a look at the harmonics of tectonic activity, we can better understand the relationships at faults and the transmission of teleseismic energy. Below are the webicorder and exp. spectrogram for Rainier.







Link to the exp. spectrograms..

http://www.geophys.washington.edu/SEIS/PNSN/WEBICORDER/SGRAM/