Dear SEISAN community,
I once again resort to this collective pool of knowledge to seek advice and
help. I've been trying on my own, with the help of the manual and
experimenting with parameters, to find the answers, but so far I have been
unsuccessful, or the answers are unclear.
If someone could help me out solving these questions I would be highly
grateful, as I've wasted too much time trying to work around them...
I post the questions here in order of priority/urgency:
Concerning the input file corr.inp:
1 - What format should the event list ("SFILE INDEXFILE" parameter) have?
Should it look like the DIRF produced files? Or a simple S-File with all
the events? I have tried both of these without success. Can anyone provide
me with an example? Also, can the list point to S-Files outside the folder?
2 - I have a big amount of master events, and a few years of continuous
data to serve as target waveforms where the correlation should be run to
find similar (new, unfound) events. Must I really input every master event
in a separated corr.inp/folder?
3 - Is there a way to point to the continuous waveforms and not to the
events? I noticed that CORR gave some segmentation faults, slicing the
waveforms in 12h segments did the trick. Since I have a big amount of data
I would prefer to store all the waveforms in one directory and just point
to that directory, so that I don't have to register these waveforms as
events in a SEISAN database... I am a bit confused here.
What I did in my trials was put the 12h segments in the same folder and
have "S-files" containing just this:
L 1
20110906_000000_taurus_0302_BHZ_00-12.mseed
6
Line 1 is always required to have at least "L" another another region
nominator, and line 6 simply tells the program which waveform to use. Is
this correct or is there a better way to point to the waveforms?
4 - Can we address other folders in this SFILE EVENT /MASTER parameters? (I
am asking this because after much trials I can only input s-files which are
on the same folder from where I am running CORR.
5 -When running with CONTINUOUS MODE = 1: There is no output of the
correlation values, I can't find it neither in the console output, nor in
the corr.out or corr.trace. How can I get the correlation value? The only
place I can read the correlation value is in the extracted waveform when it
plots the correlation trace, this is OK for small runs, but for over
hundreds of events it's not practical.
6 -When running with CONTINUOUS MODE = 0: It looks like for each phase in
the S-File, and each event S-File, CORR only picks the maximum, and not all
the local maxima above the minimum correlation threshold, am I right? It
seems like it even picks events which have a correlation below the
threshold, so far as it's a maximum.
7 - When we use Continuous Extract in CORR, it seems that in the extracted
waveforms I always get a time window equal to that of the master signal
duration + 10 seconds. How can I extend this time window? I don't mind
changing the source code, but can't find where is this hardcoded in the
source code
8 - I've got some bizarre results using CONTINUOUS MODE = 0. In one event
which had a waveform running from 00h till 12h I got the following sfile in
corr.out:
L 1
2011-09-06-0000-00S.A0302_002_P
6
2011-09-06-0000-00S.A0302_002_S
6
STAT SP IPHASW D HRMM SECON CODA AMPLIT PERI AZIMU VELO AIN AR TRES W DIS
CAZ7
A0302BZ P 240
1.90
A0302BZ S 1320
2.68
Which should read 2:40 1.9s for P and 13:20 2.68s for S, correct? Well, P
phase isn't visible (nor any seismic event in that neighbourhood) and S
phase is outside the waveform! Is this a bug, or am I just misinterpreting
the results? Also, correlation trace is around 0.3 0.2 in these cases, so
it seems it's just picking a random maxima bellow the threshold.
9 - Finally, I think I don't have to ask this, but does CORR deal with a
master and event waveform with different sample rates? My guess is we have
to make sure everything has the same SPS prior to running the routine.
I thank you very much for all the time and effort put in helping solve this
issues.
Best regards to all,
--
Emanuel Antunes
Seismology Laboratory
Instituto Superior Técnico (IST)
Universidade de Lisboa (UL)
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