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Joined: Sat Feb 23, 2008 2:29 pm


Postby raj » Sat Aug 15, 2009 8:12 am

I have some querries.
(a) While doing f-k for ambient vibration record from an array, the
*.max output is found. When it is processed with max2curve, we get two
curves , one is *.max curve and another grid statistics. In grid
statitics , we get two line----one is redline overlain by blue
line.Sir, what do they represent? Moreover, how we can process with max2cuve to get the desired dispersion curve for subsequent inversion
in dinver?
(b) In your paper"Surface -wave inversion .......ambient vibration
measurements", you have plotted sembalance maps.with sembalance
value....How can they be plotted?

> Please suggest..

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Location: ISTerre

Postby admin » Sat Oct 17, 2009 2:46 am

To answer the first question (a), the red curve is the Gaussian theoretical shape calculated from the median and the median deviation (in both plots, cumulative and density). The blue curve represent the probability density of your real data set. In an ideal world, the blue curve and the red one are close to one another. If not this means that you data statistics do no follow a Gaussian distribution and using in the inversion statistical values such as median and media deviation is not fully correct. This is rarely the case.

(b) The semblance map are extracted from the 'Test' button in the FK processing toolbox. In this 'Test' you can manually browse all individual time window and frequency band. This is the same job as when you press start. When starting the process with start, the same semblance is calculated for each frequency band and each time window. Additionally, the best peak is searched and reported in .max file.

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