Jerry,

Great response.  I quite agree, in particular, with the idea that 
there are many forces such as micro seisms and earth tides acting on 
faults, which have been determined to be larger, maybe much larger, 
than some of the proposed trigger phenomena.

Although the original post seemed to relate to longer-term trends, 
other posts suggested that some possible trigger phenomena should be 
investigated (more).  For everything mentioned so far, they all seem 
to have been well investigated, with no *significant* positive 
results yet.  That is, results initially claimed could not be 
reliably duplicated.  The issue would seem to be, how much more money 
should be spent to investigate phenomena for which there is already 
strong evidence that they are not predictively correlated in any 
useful degree with most quakes?

I am quite aware that occasionally an important scientific discovery 
is rejected by the scientific community when it is first 
proposed.  However those, over time, gather increasing supportive 
evidence and eventually become accepted.  As far as I know, the more 
that specific earthquake precursor phenomena have been objectively 
researched, the less likely it appears that they will be useful in 
predicting quakes, though I believe that there is a great incentive 
in the scientific community to discover a reliable precursor.  Any 
scientist who did would be famous.

Excellent documents on the subject with lots of references:
http://scec.ess.ucla.edu/~ykagan/perspective.html
http://earthquake.usgs.gov/learn/topics/?topicID=53&topic=Prediction

A contrary opinion, including Geller's response.
http://scec.ess.ucla.edu/~ykagan/tech_comment.html#B1-2

There's no question that new phenomena which might be predictive 
should be investigated, but if they don't prove out, it might be 
better to look elsewhere before continuing expenditures that might 
better be used for other research to reduce the damage and death toll 
of quakes.

Regards,
Brett


At 09:19 AM 6/21/2010, you wrote:
>Hi Al,
>
>I've been following the discussion about the possible affects of the 
>Sun upon earthquakes, but cannot wrap my small pea brain around that 
>notion.  Certainly, I am not expert in: geology, seismology or 
>cosmology.  However, it seems to me that any diurnal changes in 
>barometric pressure would be variable depending upon the season of 
>the year and angle of attack for the sun rays.  I acknowledge your 
>observations, but it seems that overall geographical effect would be 
>infinitesimal to the big picture of the entire Earth.
>
>I also wonder about the use of the word "cause."  Possibly, they 
>actually meant "trigger."  What was the "trigger" that set off the EQ.
>
>We all have probably read and read the books on Geology and 
>Seismology and have a fundamental understanding on the basic 
>properties that "set up" conditions for various types of quakes.  To 
>me, those conditions are pretty understandable: stress, strain, 
>elastic rebound, mantle convection, subduction and on and 
>on.  However, what exactly is the absolute "trigger" factor for a 
>given EQ may never be absolutely known.
>
>But, throwing a wide rope around the notion of influence from the 
>Sun by thermal heating of the earth or atmosphere just seems too 
>general and does not compute to me.  However, as with most ALL 
>science, it is theory and may be changed or revised some day.
>
>It is an interesting thought and should not be absolutely 
>refuted.  Never say never.......someone once said.
>
>Best Regards to the Group,
>Jerry


__________________________________________________________

Public Seismic Network Mailing List (PSN-L)