Coda window should be at least 30 seconds,
minimum correlation coefficient larger than 0.6. For comparing coda values in different
regions, ALL processing parameters must be identical including lapse time. In Havskov et al. (2016) the effect of the different parameters is investigated and a set of recomendations
are given. The parmerters found in the example file in DAT are the parmeter used in Havskov et al. (2016).
In DAT there is also an input file codaq.inp using available data in the test data base. The
input file has been created with program SELECT (option 18, station code= CODAQ, distance
range 0 to 100 km). The start of the file is
SUE SUE SUE ODD1 ODD1 ODD1 ASK ASK ASK
Z N E Z N E Z N E
OSG OSG OSG
Z N E
EGD EGD EGD BER BER BER ASK ASK ASK ODD1 ODD1 ODD1 BLS5 BLS5 BLS5 KMY KMY KMY
Z N E Z N E Z N E Z N E Z N E Z N E
which assumes that the test data base is installed under seismo. In a standard
Windows installation, that would work. Under Linux it must be change to something like
/home/seismo.... Alternatively create the file with SELECT.
Figure 27.1 gives an example of a codaq plot. There are
no options for the codaq plots and the length of the window is always
the first 200 secs from the original trace. If origin time or coda
window is outside this 200-sec window and data is available, the
program continues, but the coda window is not plotted on the figure.
An example of a coda Q plot. On top is shown the original
trace and below the filtered coda windows. Note that 15 secs of noise
are shown in front of the selected filtered coda window. The first
5 secs of the noise shown is used for calculating the S/N ratio.
On each filtered plot is given F: Center frequency, Q: Q-value, zero
means no Q-value could be calculated, S/N: Signal to noise ratio.