Is Escalating Earthquake Energy being concealed by scientific platitudes?

reply to post by luxordelphi


Yes there was a change in the way things were measured and that will have a slight effect, but the change actually meant that some figures went up and others went down.

Somewhere I have a really good example of this. If I find it I will post it.

Originally posted by PuterMan
reply to post by mbkennel

 

I accept what you are saying if you are trying to forecast unusual events, however I am not attempting to do any forecasting here.

All this is observing is that the energy release levels are going up and the trendlines are showing the trend BUT I have not created any forward figures for the trend. Since this is historic data the trendline within the dataset is perfectly valid as it is not attempting to extrapolate future trends..

OK, no predictions.

But when you say that the "trendline is up" there is an implicit expectation that there was in fact a positive trend. I am discussing some of the complications involved. Specifically, is there quantitative evidence that there even is a trend which is distinguishable from zero at some level of statistical confidence?

I agree that for forecasting one would need to go much further back, and this is an exercise that is under way, but again I doubt that it would be of any use for forecasting. The main problem being the lack of accurate older data.

I would guess you are possibly an actuary in the insurance industry?

I'm a physicist, with background in nonlinear time series analysis. I have some background knowledge of various aspects of statistics. I wouldn't know how to do lots of things, but I do know enough to have some notion of difficulties/complexities involved.

An actuary or some statisticians would have more hands-on experience on the technical methods necessary, plus you'd need a geophysicist who had deep earthquake and data set knowledge necessary to understand the underlying data and any systematic biases in it.

No one has used this system successfully to forecast earthquakes for the saving of life and limb, and I would not even attempt that. Statistically EVT might be of interest to insurance companies for the purpose of assessing premiums, but really for little else.

That's not true. It just happens to be the most profitable application.

Edit to add: The use of energy released gives a measure of the effect of plate movements since these are the major contributor to earthquake figures.

As the stress moves along a fault system so the earthquakes occur - a really good example was in Turkey where a series of quakes moved from East to West over a period of months. The total energy output in the course of a year is actually a very vague figure, but it is nonetheless an indicator of what is going on in the system as a whole. If you wanted to forecast quakes you would have to measure all the energy release in a fault system and plot the lat/lon/depth as well to get a picture of where the stresses were moving in addition to knowing the expected movement of the strike face in a given period and the friction in the system. Actually statistics have little of nothing to do with it since it is controlled by topography and plate tectonics, which is one reason why EVT will never be able to accurately predict an earthquake any better than a 'local' in the area (if it is on land).

No disagreement: statistics is only useful as a tool to help understand data in concert with physics. It has its limitations.

Putting a trendline on historic data is only a visual aid to what has passed and not to the future in any way shape or form and I apologise if I gave any other impression.

In this case there is a perception that there has been an increase in the number/intensity of earthquakes. This data confirms that.

Yes, it is suggestive. Thanks for the plots.

The data are what they are.

More interesting is whether there exists some possible physical mechanism underlying this change or whether the recent increase is easily explainable as a statistical fluctuation of a fat-tailed process.

If it isn't....

This data does NOT mean that this 'trend' will continue in 2011, or even to the end of the current year.

Evidence of a statistically significant trend might encourage one to look and search for potential physics behind it.

I think we're not that much in disagreement.

Thx for the updated graphs, really puts more of a picture to it

Just one quick question though, surely a release of energy in smaller 7-8 quakes is a good think. I think if there was almost no energy been release it would mean that its storing up for the big one...

Looks like the big one was in 2004.... maybe we will get another big one before the energy release starts to decline

reply to post by mbkennel


We are sort of back to the wording.

But when you say that the "trendline is up" there is an implicit expectation that there was in fact a positive trend.

As I have already said perhaps I would better have said "Within the set of data the line indicates that during that period under examination there was an increase overall in the energy release output on a global scale. This fact takes no account of major incidents and their aftershocks that may not be a part of normal earthquake expectation, however it has been demonstrated as in Baja that the aftershocks of an event may have very little effect on the overall energy release."

So yes the "trendline is up". After all what is normal?? Is Chile out of the norm? No, not really. Is Baja California out of the norm? Possible in terms of recent history, but is it significant? I don't know, but I think not.

This article discusses the use of EVT is earthquake magnitude estimations in catalogues. It is some 40 years since I did statistics so I am a little rusty! My impression from the document is that whilst this version they have come up with is more accurate that straight EVT......

Instead of focusing on the unstable parameter Mmax we suggest a new, stable and convenient characteristic Mmax(t) – defined as the maximum earthquake that can be recorded over a future time interval of duration t.

......the conclusion still says that even this new combination may not be accurate.

In fact, because EVT suggests a statistical methodology for the extrapolation of quantiles beyond the data range, the question whether such interpolation is justified or not in a given problem should be investigated carefully in each concrete situation. But EVT provides the best statistical approach possible in such a situation

This was my point when I said that:

Statistically EVT might be of interest to insurance companies for the purpose of assessing premiums, but really for little else.

It is not a method for predicting a quake in a specific area at a specific interval of time and never will be, and thus is not of use for saving life and limb, so I stand by my statement. The basic results for example of that study of 32,000+ quakes is that there will be an 8.5. sometime in the next 50 years (VERY simplified - see the last but one graph) To be honest it does not take EVT to 'predict' that. I am pretty sure that the consensus of opinion in Japan would be the same.

a geophysicist who had deep earthquake and data set knowledge

Note in the article they discarded deep earthquakes.

Evidence of a statistically significant trend might encourage one to look and search for potential physics behind it.

Absolutely! Something that interests me greatly - no encouragement needed, only resources!

Don't you just love statistics! In a parody of a well known statement "there's lies, there's damned lies, and then there are earthquake statistics."

Edit to add: EVT is of use in estimating ground motion after an event however. (Producing shake maps)

[edit]One more 'quotation'

Statistics means never having to say you are certain.

[edit on 12/8/2010 by PuterMan]

Originally posted by bluedrake
Just one quick question though, surely a release of energy in smaller 7-8 quakes is a good thing. I think if there was almost no energy been release it would mean that its storing up for the big one...

Looks like the big one was in 2004.... maybe we will get another big one before the energy release starts to decline

No energy release of that sort of magnitude is a good thing for the recipients!!

I do read what you are saying however, but I am not sure at this time that this is the case.

It may well be the case somewhere like Chile which has produced the worlds largest earthquake, and there a 6/7 may indicate stress relief in the subducting plate. A complete absence could indicate a 'stuck' plate and a potential for a future 'big one'.

I other areas, which have never experienced an 8+ this may not be the case. I think, as I have mentioned earlier, all these things actually have to be looked at on an area by area basis - smaller even than regions in some cases - and the overall 'grand view' of energy release only indicates that the bronco has been bucking at bit more.

Something is really rockin' the Mariana Islands right now, 12:02 CST. I have a browser add on that follows quakes and for awhile now those islands have been getting hit with 5.0+. The last is 5.7.

reply to post by DAVID64


Yes, they have had a bunch of 6+ quakes as well.

Interestingly all around one place in a similar pattern to the recent Moro Gulf quakes.

reply to post by PuterMan


EXCELLENT work. S&F Please, keep us posted.

I don't have anything to add, nor do I have any intelligent questions to ask at this time. I do, however, require that all-important second line.

Great thread, wanted to say thanks for all of your hard work and for sharing your information about escalating earthquake energy.

Wish I had something to add, but I'm still at the learning stage.

i had read somewhere on the web that usgs was now not allowed to release any info without first clearing it through homeland security, this would be relevant to this thread, but i cant find it, i was googling for awhile.

anyone know what im talking about?

Sorry to revive this thread but any updated graphs after all the EQ's in Japan?

2011 should already dwarf all other stats for past years