[MSNoise] MSNoise Digest, Vol 31, Issue 1

Thu Oct 6 17:44:36 UTC 2016

p.s.  In the admin gui, under configuration, several of the values are set
to numbers with a period "." after them. Is this necessary? E.g. are they
there to force a decimal type in python 2.x opposed to an integer?

On Thu, Oct 6, 2016 at 10:38 AM, Flinders, Ashton <aflinders at usgs.gov>
wrote:

> Thanks Esteban,
>
> I have looked through the documentation extensively, as well as the SRL
> paper, and a bit of grepping on the source code (e.g. it took me a while to
> figure out why in the world I couldnt remove instrument responses using a
> RESP or PZ file, since it is listed on the documentation page, until I
> grepped the source code and saw those were not implemented.)
>
> 1) Yes. It is more efficient to compute the cross-correlation functions or
> Green’s functions using 30-min chunks. Although you can change this feature
> if you will. Segments are re-build afterwards.
>
> This is only true if the daily segments are always preloaded into memory
> (IO vs CC time). The SRL paper makes it sounds like this is the case, but I
> want to make sure that this is always the case, even for processing many
> stations/days or long segments. I also wasnt sure if these segmented CC
> were used for any statistics (e.g. uncertainty in daily CC values).
>
> 2) You need to define the filters in order to compute the
> cross-correlations and extract the coherent part of the ambient noise for a
> given frequency range. MWCS is used to compute the moving window cross
> spectral analysis after the cross-correlation procedure.
>
> Yes, I understand that (the way its been written) filter values should be
> defined before the CC (which really should only be the whiteneing band or
> preprocessing), however I dont understand why in the web gui the whiten and
> MWCS filters are put within the same group. This make me predefine a MWCS
> filter band, along with my whiten band, even though the MWCS doesnt happed
> for another two processing steps. This leads to confusion, for example;
>
> What happens if I compute the CC's with a defined filter (as written, a
> MWCS and whiten filter defined together) and then want to compute different
> MWCS's later on when I actually get to the MWCS step. Can I just define a
> new filter, with new mwcs_low mwcs_high values? Since the web gui forces me
> to define a filter high low value (whiten, I assume) does it not use these?
> Do I have to go back and recalculate the cross correlations everytime I
> want to add an MWCS filter (which I wouldnt expect I have too)?
>
> Similarly, what happens if I want to delete a set of processed MWCS or
> stacks? I cant just delete the folder, since their are still pointers in
> the sql database. Just reprocessing doesnt seem to work either.
>
> thanks again
>
> -ashton
>
>
>
>
> On Thu, Oct 6, 2016 at 10:17 AM, Esteban Chaves <echfisica at gmail.com>
> wrote:
>
>> Hi Ashton,
>>
>> As an active user:
>>
>> I highly recommend you to check the documentation:
>> http://msnoise.org/doc/workflow.html#module-msnoise.s03compute_cc <
>> http://msnoise.org/doc/workflow.html#module-msnoise.s03compute_cc>
>> I think the pre-processing and processing steps are well documented in
>> the web site.
>>
>> 1) Yes. It is more efficient to compute the cross-correlation functions
>> or Green’s functions using 30-min chunks. Although you can change this
>> feature if you will. Segments are re-build afterwards.
>>
>> 2) You need to define the filters in order to compute the
>> cross-correlations and extract the coherent part of the ambient noise for a
>> given frequency range. MWCS is used to compute the moving window cross
>> spectral analysis after the cross-correlation procedure.
>>
>> 3) dunno. May be Thomas can give you more info.
>>
>> -Esteban J. Chaves
>>
>>
>> > On Oct 6, 2016, at 5:00 AM, msnoise-request at mailman-as.oma.be wrote:
>> >
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>> > Today's Topics:
>> >
>> >   1. new user (Flinders, Ashton)
>> >
>> >
>> > ----------------------------------------------------------------------
>> >
>> > Message: 1
>> > Date: Wed, 5 Oct 2016 13:10:53 -0700
>> > From: "Flinders, Ashton" <aflinders at usgs.gov>
>> > To: <msnoise at mailman-as.oma.be>
>> > Subject: [MSNoise] new user
>> > Message-ID:
>> >       <CAPbWHEO7J_9dyMdKJ3SQkpGy9hG7N1M-COwgzGTpkVmy85ig5g at mail.
>> gmail.com>
>> > Content-Type: text/plain; charset="UTF-8"
>> >
>> > Hi all, long-time obspy user new MSnoise user.
>> >
>> > I just had a couple quick questions I was hoping to get clarification
>> on;
>> >
>> >> From the SRL article;
>> > "Once all waveforms are loaded in memory, the computation is done by
>> > iteration of the station pairs, on the different components to compute
>> and
>> > the on the different filters for each defined window (30 minutes slices
>> by
>> > default)."
>> >
>> > 1) To be clear, the two time-series from a station-station pair are
>> divided
>> > into segments (30 minutes long, no overlap, by default), and the CC is
>> done
>> > on these segments? Are these segments then rebuilt into the daily CCF?
>> Is
>> > this segmentation purely for efficieny reasons, or is there something
>> else
>> > going on?
>> >
>> > 2) Why does msnoise compute_cc, not work if there is no MCWS filter
>> defined?
>> >
>> > 3) Is there an intelligent way to search the mailing list archive?
>> >
>> > Thanks for the help!
>> >
>> > -ashton
>> >
>> >
>> > ------------------------------
>> >
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>> >
>> > End of MSNoise Digest, Vol 31, Issue 1
>> > **************************************
>>
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>
>
>
> --
> Ashton F. Flinders, Ph.D
> U.S. Geological Survey
> 345 Middlefield Road
> Menlo Park, CA 94025
> (650) 329-5050
>
>

-- 
Ashton F. Flinders, Ph.D
U.S. Geological Survey
345 Middlefield Road
Menlo Park, CA 94025
(650) 329-5050