[Sca-cooks] Chilean Earthquake (OT)

Daniel & Elizabeth Phelps dephelps at embarqmail.com
Sat Feb 27 08:18:19 PST 2010

Was written:

I wonder how Suey is doing down there? It seems to have been as large a 
quake or even a little stronger than the one that hit Haiti. The news report 
I read sounded dire.

Please note that I'm not a seismologist but a coastal geologist who dabbles 
in shallow marine geophysics.  That being said quake magnitudes are 
logarithmic, http://en.wikipedia.org/wiki/Richter_magnitude_scale .  The 
main Haitian quake was IIRC 7.0.   The Chilean quake is reported to have 
been 8.8.   It is an under statement to say that the Chilean quake was more 
powerful.   The question is what was the apparent strength of the quake at 
various cities at distance from the epicenter.  Such can be rather quirky. 
Second question, what are the strengths of the after shocks.  Typically the 
first round of after shocks are roughly a magnitude less then the first 
quake, say 7.8  +/- .5 or so.  Thus the first after shocks are likely to be 
greater than the Haitian quake.  The second round of subsequent after shocks 
will likely to be more or less in the range of the Haitian quake, say 6.8 
+/- .5.   The third round of after shocks should ring in around 5.8 +/- .5. 
See the pattern?  This sequence does not take into account the possibility 
of additional quakes in the strength of the original, triggered by the 
original, occurring.  They are in for a rather rough ride.


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