reply to post by gringo74
The Big 1960 quake in Chile, most people don't know, but there where 2 quakes, the first one was with an epicente close to Concepcion and was
on saturday May 21st, 1960. It was 7.3 - 7.5 in magnitude.
Thanks indeed for that. I did not know that. This places it along similar line to Japan with the mag 7 before the big one. (Actually I should say
reminded me because when I looked at it I already had the info - memory not what it used to be.)
What he is saying is that in the north of Chile there hasn't been a big earthquake in 134 years, which means there is 10 meters of movement
that needs to happen. And it will happen.
I hear what you are saying but I would also comment that theoretically at least these large quakes only occur when the subduction movement gets stuck.
The quake is the result of the subsequent release.
The fact that the plate may have moved 10 metres in the given time period does NOT mean that there is 10 metres worth of built up energy. Some or all
of that 10 metres may just have slipped below the continent in the normal manner. You cannot assume that it is all stuck.
full 600km will rupture simultanously
Again he cannot state this to be a fact. 600km is also not necessarily a mag 9. It depends on the surface area of rupture.
Mag 9 in Cascadia
would be 1000km as it was in Japan - all
being approximate. The 8.8 was 2 times smaller than a mag 9 and the rupture length of 500km would indicate that.
Taking a very quick look at the historic quakes for Northern Chile, Bolivia and Northern Argentina approximately which more or less comprise the
northern elements the largish quakes of recent year have in fact apparently relieved the stress to a great extent. Here is the stress 'sawtooth' chart
for the area from 1900 to 2012
Whilst the current stress level would appear to be around 80,000TJ that is just under a mag 8.1
Consider then that a Mag 9 is 2,000,000 TJ you can see that the area has a long way to go before producing a mag 9.
I would need to refine these better as it was a rush job but based on this I would say that a mag 9 is extremely unlikely if not impossible.
I had a look at that video. Basically he is saying that there is a 600km section that is locked based on quakes that happened around the area. I am
not sure, this area being on a curve, that you can say that however I noted that he says that there has not been a quake since 1877 but i could not
pick up what magnitude quake that was.
If I can find that information, and now knowing what area he is talking about I can recalculate that stress chart.
edit on 26/3/2012 by PuterMan because: (no reason given)